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cmd/go: define HTTP authentication extension mechanism #26232

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draftcode opened this issue Jul 5, 2018 · 66 comments
Open

cmd/go: define HTTP authentication extension mechanism #26232

draftcode opened this issue Jul 5, 2018 · 66 comments

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@draftcode
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@draftcode draftcode commented Jul 5, 2018

Problem

The custom import path mechanism (?go-get=1 and meta tag) works for public URLs, but it doesn't work for auth required URLs. This is because when go-get fetches the URL with ?go-get=1, it uses net/http.DefaultClient, and it doesn't know the credentials it needs to access the URL. A user cannot run go get against private source code hosting service because of this.

Goal

Make go get git.mycompany.com/private-repo work, where https://git.mycompany.com/private-repo requires authentication.

Idea 1 (credential helper)

Introduce a credential helper mechanism like git-credential-helpers. A user specifies a path to a binary via GOGET_CREDENTIAL_HELPER and go get executes that with the import path as an argument. The credential helper binary returns HTTP headers (like "Authorization: Basic blah\n", and go get adds these headers when it tries to fetch go-get=1 URLs.

  • PRO: Straightforward solution to the problem description.
  • CON: Supporting multiple credential helpers becomes complicated. Git's credential helper mechanism supports multiple credential helper, and Git runs each in order. This sometimes makes an unexpected behavior that is hard to debug.

Idea 2 (go-get helper)

Introduce a custom source code fetching mechanism. When go get needs to fetch the source code for the import path git.mycompany.com/private-repo, it looks for the binary go-get-git.mycompany.com based on the host name of the import path. When such binary exists in $PATH, it executes that binary with the import path and a destination in $GOPATH (for example, go-get-git.mycompany.com git.mycompany.com/private-repo $GOPATH/src/git.mycompany.com/private-repo). The binary is responsible for fetching the source code to the specified $GOPATH location.

  • PRO: As a side effect, this make go get work with VCSs other than git/hg/svn/bzr.
  • CON: I'm not sure how this works with go get -f or go get -insecure.
@gopherbot gopherbot added this to the Proposal milestone Jul 5, 2018
@gopherbot gopherbot added the Proposal label Jul 5, 2018
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@draftcode draftcode commented Jul 5, 2018

Related issues: #16315 #11032

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@rsc rsc commented Jul 5, 2018

The original vgo prototype just read $HOME/.netrc. I'd rather do something like that than shell out to a whole separate program.

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@draftcode draftcode commented Jul 6, 2018

.netrc works for HTTP basic auth with unlimited lifetime credentials. But it doesn't work for other types, like:

  • OAuth2 access tokens. OAuth2 access tokens usually have a limited lifetime, and it needs to be issued dynamically. Because of this, this cannot be in a static file.
  • Cookie based auth. netrc as a format is not a format that represent an HTTP cookie. Alternatively, Netscape's cookie file format (the same format as .gitcookies) can be used. This cannot support dynamically generated credentials as well. We actually have Git repositories that are behind dynamically generated cookie-based auth at Google (BeyondCorp at Google: https://cloud.google.com/beyondcorp/).
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@rsc rsc commented Jul 9, 2018

Note that even "access denied" pages can have meta tags - go get does not require a 200 response, exactly for this kind of thing. So git.mycompany.com could serve the tags unauthenticated as one workaround.

Are there any more general "HTTP auth credential helpers" in the world besides git-credential-helper? How do other systems deal with this? If there's something standard to hook into (like .netrc) then that's better than designing our own.

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@draftcode draftcode commented Jul 9, 2018

If the access denied page contains the meta tag, it can be used as a prober. Let's say git.mycompany.com has an not-yet announced new product, collaborating with another company other-tech-company.com, and they host a Git repository at git.mycompany.com/ng-product/collab-other-tech-company. An attacker can probe if a repository exists by looking at the go-get's meta tag, and they can learn mycompany.com will have a business relationship other-tech-company.com to create a new product (and maybe benefit from this insider info).

As far as I know, there's no generic mechanism that majority of people use for storing and obtaining credentials through API. The closest thing I can think of is ssh-agent. Or if it's OS X, OS X Keychain.

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@rsc rsc commented Jul 23, 2018

It's only a prober if you check that the thing exists before serving the meta-tag.

$ curl 'https://rsc.io/asdgihopajdfklgadfglhifsdfj?go-get=1'
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<meta name="go-import" content="rsc.io/asdgihopajdfklgadfglhifsdfj git https://github.com/rsc/asdgihopajdfklgadfglhifsdfj">
<meta http-equiv="refresh" content="0; url=https://godoc.org/rsc.io/asdgihopajdfklgadfglhifsdfj">
</head>
<body>
Redirecting to docs at <a href="https://godoc.org/rsc.io/asdgihopajdfklgadfglhifsdfj">godoc.org/rsc.io/asdgihopajdfklgadfglhifsdfj</a>...
</body>
</html>
r$ 
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@rsc rsc commented Jul 23, 2018

Clearly we could use a better idea here but I'd like to have just one thing that's standard instead of inventing our own (that is, I want something like .netrc).

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@draftcode draftcode commented Jul 27, 2018

It's only a prober if you check that the thing exists before serving the meta-tag.

I cannot interpret this. The problem is that an attacker can use this to extract the repository existence by using this meta-tag. If the page checks if the repository exists and change the response, it can be used as a prober.

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@rsc rsc commented Aug 13, 2018

If the page checks if the repository exists and change the response, it can be used as a prober.

Then don't check, and don't change the response.

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@bradfitz bradfitz commented Aug 13, 2018

Are there any more general "HTTP auth credential helpers" in the world besides git-credential-helper?

https://docs.docker.com/engine/reference/commandline/login/#credentials-store

https://github.com/GoogleCloudPlatform/docker-credential-gcr

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@draftcode draftcode commented Aug 13, 2018

Then don't check, and don't change the response.

So the page should not do any auth, and should not contain meta tag? I thought you're suggesting to add a meta tag and in the next response you're saying not to add meta tag?

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@draftcode draftcode commented Aug 13, 2018

An example leakage: https://play.golang.org/p/rCYzVWQSQni

We want to avoid this. By adding a meta-tag to the response as rsc suggests, the repository existence is leaked.

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@bradfitz bradfitz commented Aug 13, 2018

@draftcode, I assumed what was meant as you should advertise it for all URLs, including /android/device/g000gle/foo-bar-not-exist , regardless of whether it actually exists.

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@draftcode draftcode commented Aug 13, 2018

I assumed what was meant as you should advertise it for all URLs, including /android/device/g000gle/foo-bar-not-exist , regardless of whether it actually exists.

Note that the third part in meta tag should be a git repository URL. This means, if a repository exists, the third part should be a valid Git repository path. In the example, I used example.com/android/device/google/marlin-kernel/foo/bar as an example package path. The valid meta tag for this is <meta name="go-import" content="example.com git http://example.com/android/device/google/marlin-kernel">, not <meta name="go-import" content="example.com git http://example.com/android/device/google/marlin-kernel/foo/bar">. Because of this, I can tell whether a repository exists by adding paths that wouldn't exist. When I make a request, if meta tag's returned path is modified, it means the repository exists.

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@draftcode draftcode commented Aug 13, 2018

An example that for this: https://play.golang.org/p/OWb6zRUD02r

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@rsc rsc commented Aug 14, 2018

@draftcode I am saying that if you pick a trivial rule like "example.com/x/y/z/w redirects to the repo at git.example.com/x/y", then you can implement it with no Auth check and no repo validity check, so that it responds to any possible x/y/z/w with the same answer. Then there is no leakage. That was the point of my curl example above: there is no actual package at rsc.io/asdgihopajdfklgadfglhifsdfj but the curl still reads back meta tags for it.

If you need example.com/x/y/z/w to redirect to different git servers based on the exact values of x,y,z,w then that's more difficult of course and leakage is hard to avoid.

This is all just a suggested workaround. What I'd really like is to find out about some plausibly general (not git-specific, not docker-specific) semi-standard way to interact with credential helpers. Maybe none exists and we have to come up with something. But that would be my last choice.

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@draftcode draftcode commented Aug 14, 2018

If you need example.com/x/y/z/w to redirect to different git servers based on the exact values of x,y,z,w then that's more difficult of course and leakage is hard to avoid.

OK. We've considered that option when we investigated how GitHub deals with this, and found out that GitHub won't allow slashes in a repository name, so they can do what you've said. We cannot do that, so filed this bug.

What I'd really like is to find out about some plausibly general (not git-specific, not docker-specific) semi-standard way to interact with credential helpers. Maybe none exists and we have to come up with something. But that would be my last choice.

So far, I've shown what Git does for a similar problem. @bradfitz showed what Docker and GCP does for a similar problem (ADC now works only for service accounts, so it's a bit different). If there's a some standard way to get a cred, considering the size of these tools' community, there should be some implementation of that, but it seems there's no such thing. In fact, Docker created a credential helper mechanism following what Git did. From these, such standard, if exists, is something that Git and Docker communities at least are not aware of and are not using. @rsc, @bradfitz, and I are also not aware of such generic way that would be called as "semi-standard", it seems.

@rsc rsc changed the title proposal: make go-get work for private source code hosting services proposal: cmd/go: define HTTP authentication extension mechanism Aug 20, 2018
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@rsc rsc commented Aug 20, 2018

Given that there doesn't seem to be an agreed-upon standard, I guess the next step is for someone to propose a design that Go should use. I looked at git credential helpers but stopped looking when I saw bash snippets.

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@draftcode draftcode commented Aug 26, 2018

Questions on the requirements:

  • My impression is that @rsc strongly prefers using a file instead of executing a command and using stdin/stdout. Is this a hard requirement?
    • If this is a requirement, this means that Go cannot support OS-standard credential management mechanisms.
    • Also this makes it hard to protect credentials. If this is done in stdin/stdout, the credential manager side can do a necessary re-auth.
  • This is just "defining a protocol between Go's toolchain and a user-defined credential manager", right? We do not want to create a password manager like LastPass for this purpose.
  • With a user-defined credential manager, users should be able to:
    • Add an HTTP header (including cookies)
    • Add an SSL client certificate
    • Anything else?
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@josharian josharian commented Aug 26, 2018

My impression is that @rsc strongly prefers using a file instead of executing a command and using stdin/stdout. Is this a hard requirement?

He objected to bash snippets. It is possible (I do not know) that executing a binary rather than a shell might sit better with him.

If it were indeed command execution (a la EDITOR), then e.g. those of us who use 1password could use their command line support. I think macOS keychain has similar support.

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@rsc rsc commented Sep 19, 2018

Command-line execution seems necessary, since you want to lock things down and give cmd/go access to just one password, not your whole password set. Josh, what did you have in mind? Want to propose a starting point design?

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@dmitris dmitris commented Sep 25, 2018

It would be great if we could achieve the stated above goal ("Make go get git.mycompany.com/private-repo work, where https://git.mycompany.com/private-repo requires authentication") without forcing the users to perform custom modifications to their ~/.netrc or ~/.gitconfig files (or installing extra binaries) - at least in the (I believe) common cases of GitHub [Enterprise] with SSH authentication (from the ssh agent).

Assuming the server returns a meta tag such as <meta name="go-import" content="git.mycompany.com/org/repo git https://git.mycompany.com/org/repo.git">, could the go tool try the following:

  • shell out git ls-remote -q https://git.mycompany.com/org/repo.git first (as now)
  • if it gets a response with an auth prompt: Username for 'https://git.mycompany.com':, try next the command with the corresponding ssh URL: git ls-remote -q ssh://git@git.mycompany.com/org/repo.git - and if it works, remember / cache that protocol for other git operations with the server (at least, within the same go invocation). (The git user must be standard for GitHub as it is indicated on https://help.github.com/articles/testing-your-ssh-connection/ and https://help.github.com/enterprise/2.14/user/articles/testing-your-ssh-connection/). This "retrial" step can be limited to the cases where server replies with Server: Github.com HTTP header ([1], [2]).

I believe this would make possible to use git with the SSH auth without having everyone to add the insteadOf stanzas in ~/.gitconfig on every server / VM or putting passwords in ~/.netrc etc. (To avoid this, we currently have to use a redirect server on an equivalent of go.mycompany.com that sends back <meta name="go-import" content="git.mycompany.com/org/repo git ssh://git@git.mycompany.com/org/repo"> - but it would be so nice to be able to use the "natural" git.mycompany.com/org/repo as imports / package names instead of go.mycompany.com and forcing everyone to learn and use the git.mycompany.com => go.mycompany.com replacement!) Having all Go users in the company to install an additional binary to bridge go and auth secrets would IMO be even more cumbersome (and the security team will likely consider it as yet another thing to worry about...).

I think it is an incredible strength of the Go tool that you can install and use it "right out of the box" - would love to see that feature and stellar user experience preserved and extended! 😄

[1] https://go-review.googlesource.com/c/go/+/33171 (abandoned; issue https://golang.org/issue/17898)
[2] Russ's comment - #24076 (comment)

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@draftcode draftcode commented Sep 29, 2018

Assuming the server returns a meta tag

@dmitris This proposal is for the servers that cannot return meta tags without an auth (see #26232 (comment)). It seems to me that your problem is not related to this.

gopherbot pushed a commit to golang/build that referenced this issue Apr 5, 2019
…h authentication

• The /auth subdirectory wasn't downloading content from GCS.

• The zip extraction logic was failing for zip files that do not
  contain explicit directory entries.

• The invocation of http.FileServer wasn't trimming the /auth prefix,
  so rejections would work correctly but successful authentication
  would return 404s instead of serving the file.

Updates golang/go#26232

Change-Id: I3a72d7dfca62435c53f4bc7efaebae3900f2c175
Reviewed-on: https://go-review.googlesource.com/c/build/+/170880
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
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@rsc rsc commented Apr 10, 2019

Looks good. On Feb 13 I asked if anyone objected to this proposal, and as far as I can tell no one has. Accepting.

@rsc rsc changed the title proposal: cmd/go: define HTTP authentication extension mechanism cmd/go: define HTTP authentication extension mechanism Apr 10, 2019
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@palsivertsen palsivertsen commented Apr 12, 2019

You only get to pick two of those: “requires authentication” and “authenticating […] is not an option” are mutually exclusive.

Sorry, poor choice of words from my side. What I was trying to say is that HTTP is not an option, but other protocols are, e.g. SSH. Making HTTP calls that requires authentication is (IMO) a poor choice compared to SSH because it requires either user interaction (2FA) or weak credentials (compared to SSH). Another argument to drop HTTP is that SSH credentials are in most cases only authorized for GIT, but HTTP credentials in some cases gives access to a wider API.

Maybe my usecase is not relevant to what's described in this issue.

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@bcmills bcmills commented Apr 12, 2019

@palsivertsen, the protocol-selection issue you describe was discussed in #30304 (and declined on the grounds of not being worth the extra complexity; see #30304 (comment)).

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@gopherbot gopherbot commented Apr 17, 2019

Change https://golang.org/cl/172599 mentions this issue: cmd/go/internal/base: add a Logf function and funnel stderr output through it

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@gopherbot gopherbot commented Apr 17, 2019

Change https://golang.org/cl/172617 mentions this issue: cmd/go: set GIT_TERMINAL_PROMPT on individual git commands instead of process-wide

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@hyangah hyangah commented Apr 17, 2019

@bcmills I want to make sure I understand how this protocol works with GOPROXY and private repos. Correct me if wrong.

Option 1. Utilizing the functionalities added for #26334. User specifies GOPROXY=https://public_proxy,direct

  • Go command tries to fetch https://public_proxy/private_repo/package/path
  • The public_proxy will not be able to access the private repo, so returns 4XX.
  • Go command runs $GOAUTH with https://public_proxy/private_repo/package/path as an arg, which fails.
  • Go command tries with the next one in GOPROXY (direct in this example).
  • The private repo requires credential, so returns 4XX.
  • Go command runs $GOAUTH with https://private_repo/package/path as an arg, which succeeds.
  • Go command fetches data from the private repo using the credential.

Option 2. Utilizing the new GONOPROXY env var proposed in
https://go.googlesource.com/proposal/+/master/design/25530-notary.md#command-client.
User specifies GONOPROXY=private_repo GOPROXY=https://public_proxy

  • Go command knows the private_repo shouldn't use the proxy, so directly contact the private_repo, and fails with 4XX (403)
  • Go command runs $GOAUTH with https://private_repo/package/path and acquires the credential.
  • Go command fetches data from the private repo using the credential.
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@bcmills bcmills commented Apr 18, 2019

@hyangah, since GOAUTH may be interactive, I think we want to avoid running it until we have exhausted all other options. For your Option 1, that suggests something more like:

  • Go command tries to fetch https://public_proxy/private_repo/package/path
  • The public_proxy will not be able to access the private repo, so returns 4XX.
  • Go command tries with the next one in GOPROXY (direct in this example).
  • The private repo requires credential, so returns 4XX.
  • Go command runs $GOAUTH with https://public_proxy/private_repo/package/path as an arg, which fails, so it does not retry the public proxy.
  • Go command runs $GOAUTH with https://private_repo/package/path as an arg, which succeeds.
  • Go command fetches data from the private repo using the credential.

That reduces the number of user interactions required if the proxy declines the request but the direct fetch succees. However, it implies that if one wants to avoid leaking paths from one proxy to another, the chosen GOPROXY command must report all applicable credentials upfront (during the initial “no URL” phase) instead of waiting for requests for specific URLs.

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@hyangah hyangah commented Apr 18, 2019

Thanks for the clarification, @bcmills

However, it implies that if one wants to avoid leaking paths from one proxy to another, the chosen GOPROXY command must report all applicable credentials upfront (during the initial “no URL” phase) instead of waiting for requests for specific URLs.

Does that mean, if the GOAUTH program returns the credential for https://private_repo/ during the initial no URL phase, the Go command will not try to use GOPROXY for the package that prefixes with the private_repo so the private package path and repo names will not leak? That's great.

If I have some private repositories in github.com accessible with my github.com credential, but I still want to utilize the public GOPROXY for other public modules and packages, do I need to configure the GOAUTH program to return the explicit list of private repositories in the github.com with my github.com credentials?

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@gopherbot gopherbot commented Apr 19, 2019

Change https://golang.org/cl/173017 mentions this issue: cmd/go: query modules in parallel

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@bcmills bcmills commented Apr 19, 2019

Does that mean, if the GOAUTH program returns the credential for https://private_repo/ during the initial no URL phase, the Go command will not try to use GOPROXY for the package that prefixes with the private_repo so the private package path and repo names will not leak?

I'm not sure exactly what you're asking, but I wasn't planning to use the set of credentials to decide which modules to ask the proxy about.

If I have some private repositories in github.com accessible with my github.com credential, but I still want to utilize the public GOPROXY for other public modules and packages, do I need to configure the GOAUTH program to return the explicit list of private repositories in the github.com with my github.com credentials?

If you don't care about leaking your private repo paths to the proxy, then you can run git config --global credential.helper cache or git config --global credential.helper 'store --file ~/.my-credentials', then git credential approve the credentials for your private repos, and finally set GOAUTH=git to use those stored credentials. (To my knowledge git does not have a API for enumerating existing credentials, so the GOAUTH initial pass won't pick them up anyway.)

If you do care about leaking your private repo paths, then you'll still have to use GONOPROXY or similar.

gopherbot pushed a commit that referenced this issue Apr 23, 2019
The cmd/go/internal/web package was forked in order to support direct
HTTPS fetches from widely-used hosting providers,¹ but direct fetches
were subsequently dropped in CL 107657. The forked web2 package, with
its GitHub-specific diagnostics and .netrc support, remained in use
for module proxy support, but was not used for the initial '?go-get=1'
path resolution, so the .netrc file was only used to fetch from
already-resolved module protocol servers.

This CL moves the .netrc support into its own (new) package,
cmd/go/internal/auth, and consolidates the web and web2 packages back
into just web. As a result, fetches via the web package now support
.netrc, and fetches that previously used web2 now enforce the same
security policies as web (such as prohibiting HTTPS-to-HTTP
redirects).

¹golang/vgo@63138cb

Fixes #29591
Fixes #29888
Fixes #30610
Updates #26232

Change-Id: Ia3a13526e443679cf14a72a1f3db96f336ce5e73
Reviewed-on: https://go-review.googlesource.com/c/go/+/170879
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
gopherbot pushed a commit that referenced this issue Apr 30, 2019
Refactor modload.QueryPackage and modload.QueryPattern to share code.

Fine-tune error reporting and make it consistent between QueryPackage and QueryPattern.

Expand tests for pattern errors.

Update a TODO in modget/get.go and add a test case that demonstrates it.

Updates #26232

Change-Id: I900ca8de338ef9a51b7f85ed93d8bcf837621646
Reviewed-on: https://go-review.googlesource.com/c/go/+/173017
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>
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@bcmills bcmills commented May 7, 2019

I had to pause development on this before the 1.13 freeze due to a personal emergency, and as a result it didn't make the freeze.

Given that it appears likely that modules will still be auto rather than on by default (#31857), and given the subtle interactions between GOAUTH, package-to-module resolution, and proxy fallback (#26334), I think this needs to wait for 1.14.

@bcmills bcmills modified the milestones: Go1.13, Go1.14 May 7, 2019
Kiku-Reise added a commit to Kiku-Reise/go that referenced this issue May 16, 2019
fix (#1)
* cmd/compile: add unsigned divisibility rules

"Division by invariant integers using multiplication" paper
by Granlund and Montgomery contains a method for directly computing
divisibility (x%c == 0 for c constant) by means of the modular inverse.
The method is further elaborated in "Hacker's Delight" by Warren Section 10-17

This general rule can compute divisibilty by one multiplication and a compare
for odd divisors and an additional rotate for even divisors.

To apply the divisibility rule, we must take into account
the rules to rewrite x%c = x-((x/c)*c) and (x/c) for c constant on the first
optimization pass "opt".  This complicates the matching as we want to match
only in the cases where the result of (x/c) is not also available.
So, we must match on the expanded form of (x/c) in the expression x == c*(x/c)
in the "late opt" pass after common subexpresion elimination.

Note, that if there is an intermediate opt pass introduced in the future we
could simplify these rules by delaying the magic division rewrite to "late opt"
and matching directly on (x/c) in the intermediate opt pass.

Additional rules to lower the generic RotateLeft* ops were also applied.

On amd64, the divisibility check is 25-50% faster.

name                     old time/op  new time/op  delta
DivconstI64-4            2.08ns ± 0%  2.08ns ± 1%     ~     (p=0.881 n=5+5)
DivisibleconstI64-4      2.67ns ± 0%  2.67ns ± 1%     ~     (p=1.000 n=5+5)
DivisibleWDivconstI64-4  2.67ns ± 0%  2.67ns ± 0%     ~     (p=0.683 n=5+5)
DivconstU64-4            2.08ns ± 1%  2.08ns ± 1%     ~     (p=1.000 n=5+5)
DivisibleconstU64-4      2.77ns ± 1%  1.55ns ± 2%  -43.90%  (p=0.008 n=5+5)
DivisibleWDivconstU64-4  2.99ns ± 1%  2.99ns ± 1%     ~     (p=1.000 n=5+5)
DivconstI32-4            1.53ns ± 2%  1.53ns ± 0%     ~     (p=1.000 n=5+5)
DivisibleconstI32-4      2.23ns ± 0%  2.25ns ± 3%     ~     (p=0.167 n=5+5)
DivisibleWDivconstI32-4  2.27ns ± 1%  2.27ns ± 1%     ~     (p=0.429 n=5+5)
DivconstU32-4            1.78ns ± 0%  1.78ns ± 1%     ~     (p=1.000 n=4+5)
DivisibleconstU32-4      2.52ns ± 2%  1.26ns ± 0%  -49.96%  (p=0.000 n=5+4)
DivisibleWDivconstU32-4  2.63ns ± 0%  2.85ns ±10%   +8.29%  (p=0.016 n=4+5)
DivconstI16-4            1.54ns ± 0%  1.54ns ± 0%     ~     (p=0.333 n=4+5)
DivisibleconstI16-4      2.10ns ± 0%  2.10ns ± 1%     ~     (p=0.571 n=4+5)
DivisibleWDivconstI16-4  2.22ns ± 0%  2.23ns ± 1%     ~     (p=0.556 n=4+5)
DivconstU16-4            1.09ns ± 0%  1.01ns ± 1%   -7.74%  (p=0.000 n=4+5)
DivisibleconstU16-4      1.83ns ± 0%  1.26ns ± 0%  -31.52%  (p=0.008 n=5+5)
DivisibleWDivconstU16-4  1.88ns ± 0%  1.89ns ± 1%     ~     (p=0.365 n=5+5)
DivconstI8-4             1.54ns ± 1%  1.54ns ± 1%     ~     (p=1.000 n=5+5)
DivisibleconstI8-4       2.10ns ± 0%  2.11ns ± 0%     ~     (p=0.238 n=5+4)
DivisibleWDivconstI8-4   2.22ns ± 0%  2.23ns ± 2%     ~     (p=0.762 n=5+5)
DivconstU8-4             0.92ns ± 1%  0.94ns ± 1%   +2.65%  (p=0.008 n=5+5)
DivisibleconstU8-4       1.66ns ± 0%  1.26ns ± 1%  -24.28%  (p=0.008 n=5+5)
DivisibleWDivconstU8-4   1.79ns ± 0%  1.80ns ± 1%     ~     (p=0.079 n=4+5)

A follow-up change will address the signed division case.

Updates #30282

Change-Id: I7e995f167179aa5c76bb10fbcbeb49c520943403
Reviewed-on: https://go-review.googlesource.com/c/go/+/168037
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/link/internal/ld: consolidate macho platform setup

Determine the macho platform once and use that the two places that
need it. This makes it easier to add a third platform check for a
follow-up change.

Updates #31447

Change-Id: I522a5fface647ab8e608f816c5832d531534df7a
Reviewed-on: https://go-review.googlesource.com/c/go/+/174198
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/link/internal/ld,syscall: drop $INODE64 suffixes on simulators

Some libc functions are suffixed with "$INODE64" on macOS.
Unfortunately, the iOS simulator doesn't have the suffixes, so we can't
use GOARCH to distinguish the two platform.

Add linker support for adding the suffix, using the macho platform
to determine whether it is needed.

While here, add the correct suffix for fdopendir on 386. It's
"$INODE64$UNIX2003", believe it or not. Without the suffix,

GOARCH=386 go test -short syscall

crashes on my Mojave machine.

Fixes #31447

Change-Id: I9bd3de40ece7df62f744bc24cd00909e56b00b78
Reviewed-on: https://go-review.googlesource.com/c/go/+/174199
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/link/internal/ld,syscall: replace getfsstat64 with getfsstat

getfsstat64 is deprecated but not yet caught by the App Store checks.
Use the supported getfsstat$INODE64 form instead to ensure forward
compatibility.

Change-Id: I0d97e8a8b254debb3de1cfcb3778dbed3702c249
Reviewed-on: https://go-review.googlesource.com/c/go/+/174200
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/go/internal/renameio: use ERROR_ACCESS_DENIED to check for errors

CL 172418 added code to check for "Access is denied" error.
But "Access is denied" error will be spelled differently on
non-English version of Windows.

Check if error is ERROR_ACCESS_DENIED instead.

Updates #31247

Change-Id: I7b1633013d563f7c06c1f12a9be75122106834f9
Reviewed-on: https://go-review.googlesource.com/c/go/+/174123
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

* syscall: allow setting security attributes on processes

This allows creating processes that can only be debugged/accessed by
certain tokens, according to a particular security descriptor. We
already had everything ready for this but just neglected to pass through
the value from the user-accessible SysProcAttr.

Change-Id: I4a3fcc9f5078aa0058b26c103355c984093ae03f
Reviewed-on: https://go-review.googlesource.com/c/go/+/174197
Run-TryBot: Jason Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

* runtime: remove spurious register loads for openbsd/amd64 kqueue

The kqueue system call takes no arguments, hence there should be no need
to zero the registers used for the first syscall arguments.

Change-Id: Ia79b2d4f4d568bb6795cb885e1464cf1fc2bf7c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/174128
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>

* cmd/compile: intrinsify math/bits.Add64 for ppc64x

This change creates an intrinsic for Add64 for ppc64x and adds a
testcase for it.

name               old time/op  new time/op  delta
Add64-160          1.90ns ±40%  2.29ns ± 0%     ~     (p=0.119 n=5+5)
Add64multiple-160  6.69ns ± 2%  2.45ns ± 4%  -63.47%  (p=0.016 n=4+5)

Change-Id: I9abe6fb023fdf62eea3c9b46a1820f60bb0a7f97
Reviewed-on: https://go-review.googlesource.com/c/go/+/173758
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Run-TryBot: Carlos Eduardo Seo <cseo@linux.vnet.ibm.com>

* runtime: whitelist debugCall32..debugCall65536 in debugCallCheck

Whitelists functions debugCall32 through debugCall65536 in
runtime.debugCallCheck so that any instruction inside those functions
is considered a safe point.
This is useful for implementing nested function calls.

For example when evaluating:

	f(g(x))

The debugger should:

1. initiate the call to 'f' until the entry point of 'f',
2. complete the call to 'g(x)'
3. copy the return value of 'g(x)' in the arguments of 'f'
4. complete the call to 'f'

Similarly for:

	f().amethod()

The debugger should initiate the call to '.amethod()', then initiate
and complete the call to f(), copy the return value to the arguments
of '.amethod()' and finish its call.
However in this example, unlike the other example, it may be
impossible to determine the entry point of '.amethod()' until after
'f()' is evaluated, which means that the call to 'f()' needs to be
initiated while stopped inside a debugCall... function.

Change-Id: I575c23542709cedb1a171d63576f7e11069c7674
Reviewed-on: https://go-review.googlesource.com/c/go/+/161137
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>

* strconv: Document ParseFloat's special cases

Updates #30990

Change-Id: I968fb13251ab3796328089046a3f0fc5c7eb9df9
Reviewed-on: https://go-review.googlesource.com/c/go/+/174204
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go: implement Go checksum database support

This CL adds support for consulting the Go checksum database
when downloading a module that is not already listed in go.sum.
The overall system is described at golang.org/design/25530-sumdb,
and this CL implements the functionality described specifically in
golang.org/design/25530-sumdb#command-client.

Although the eventual plan is to set GOPROXY and GOSUMDB to
default to a Google-run proxy serving the public Go ecosystem,
this CL leaves them off by default.

Fixes #30601.

Change-Id: Ie46140f93c6cc2d85573fbce0878a258819ff44d
Reviewed-on: https://go-review.googlesource.com/c/go/+/173951
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* encoding/json: add a Fuzz function

Adds a sample Fuzz test function to package encoding/json following the
guidelines defined in #31309, based on
https://github.com/dvyukov/go-fuzz-corpus/blob/master/json/json.go

Fixes #31309
Updates #19109

Change-Id: I5fe04d9a5f41c0de339f8518dae30896ec14e356
Reviewed-on: https://go-review.googlesource.com/c/go/+/174058
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* all: remove a few unused parameters

I recently modified tabwriter to reduce the number of defers due to
flush calls. However, I forgot to notice that the new function
flushNoDefers can no longer return an error, due to the lack of the
defer.

In crypto/tls, hashForServerKeyExchange never returned a non-nil error,
so simplify the code.

Finally, in go/types and net we can find a few trivially unused
parameters, so remove them.

Change-Id: I54c8de83fbc944df432453b55c93008d7e810e61
Reviewed-on: https://go-review.googlesource.com/c/go/+/174131
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>

* net/http: remove "number:" from Response.Status string

The behavior of Value.String method on non-string JavaScript types has
changed after CL 169757.

Update the implementation of Transport.RoundTrip method to construct the
Response.Status string without relying on result.Get("status").String(),
since that now returns strings like "<number: 200>" instead of "200".

Fixes #31736

Change-Id: I27b3e6cc95aa65fd1918b1400e88478a154aad12
Reviewed-on: https://go-review.googlesource.com/c/go/+/174218
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Richard Musiol <neelance@gmail.com>

* cmd/link/internal/s390x: fix s390x build

Fix breakage from CL 173437

Change-Id: If218ffaa1259fbdee641143ffbe4b38030c373b9
Reviewed-on: https://go-review.googlesource.com/c/go/+/174278
Reviewed-by: Michael Munday <mike.munday@ibm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

* net: correct docs of KeepAlive field in Dialer type

KeepAlive field used to report the wording "keep-alive period"
which may be misleading. This field does not represent the whole
TCP keepalive time, that is the inactivity period upon which one
endpoint starts probing the other end. But it acctually specifies
the keepalive interval, that is the time between two keepalive
probes.

Fixes #29089

Change-Id: If99b38ba108830d0e5fe527171a2f5c96a3bcde7
Reviewed-on: https://go-review.googlesource.com/c/go/+/155960
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* misc/wasm: fix command line arguments containing multi-byte characters

Command line arguments containing multi-byte characters were causing
go_js_wasm_exec to crash (RangeError: Source is too large), because
their byte length was not handled correctly. This change fixes the bug.

Fixes #31645.

Change-Id: I7860ebf5b12da37d9d0f43d4b6a22d326a90edaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/173877
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* runtime: initialise cpu.HWCap on openbsd/arm64

OpenBSD does not provide auxv, however we still need to initialise cpu.HWCap.
For now initialise it to the bare minimum, until some form of CPU capability
detection is implemented or becomes available - see issue #31746.

Updates #31656

Change-Id: I68c3c069319fe60dc873f46def2a67c9f3d937d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/174129
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* runtime: support all as parameter in gdb goroutine commands.

For example, can use `goroutine all bt` to dump all goroutines'
information.

Change-Id: I51b547c2b837913e4bdabf0f45b28f09250a3e34
GitHub-Last-Rev: d04dcd4f581f97e35ee45969a864f1270d79e49b
GitHub-Pull-Request: golang/go#26283
Reviewed-on: https://go-review.googlesource.com/c/go/+/122589
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Reviewed-by: David Chase <drchase@google.com>

* os/exec: always set SYSTEMROOT on Windows if not listed in Cmd.Env

Fixes #25210

Change-Id: If27b61776154dae9b9b67bf4e4f5faa785d98105
Reviewed-on: https://go-review.googlesource.com/c/go/+/174318
Reviewed-by: Ian Lance Taylor <iant@golang.org>

* runtime/cgo: ignore missing Info.plist files on iOS

When running Go programs on Corellium virtual iPhones, the Info.plist
files might not exist. Ignore the error.

Updates #31722

Change-Id: Id2e315c09346b69dda9e10cf29fb5dba6743aac4
Reviewed-on: https://go-review.googlesource.com/c/go/+/174202
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* syscall: don't return EINVAL on zero Chmod mode on Windows

Fixes #20858

Change-Id: I45c397795426aaa276b20f5cbeb80270c95b920c
Reviewed-on: https://go-review.googlesource.com/c/go/+/174320
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* testing: delay flag registration; move to an Init function

Any code that imports the testing package forces the testing flags to be
defined, even in non-test binaries. People work around this today by
defining a copy of the testing.TB interface just to avoid importing
testing.

Fix this by moving flag registration into a new function, testing.Init.
Delay calling Init until the testing binary begins to run, in
testing.MainStart.

Init is exported for cases where users need the testing flags to be
defined outside of a "go test" context. In particular, this may be
needed where testing.Benchmark is called outside of a test.

Fixes #21051

Change-Id: Ib7e02459e693c26ae1ba71bbae7d455a91118ee3
Reviewed-on: https://go-review.googlesource.com/c/go/+/173722
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* runtime: make mmap return 0 instead of -1 on aix/ppc64

Most of the platforms are returning 0 instead of -1 when mmap syscalls
is failing. This patch corrects it for AIX in order to fix
TestMmapErrorSign and to improve AIX compatibility.

Change-Id: I1dad88d0e69163ad55c504b2b4a997892fd876cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/174297
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

* cmd/go: add XCOFF format handler for go version

Change-Id: Ib102ae95acfd89fc3c9942a4ec82c74362f62045
Reviewed-on: https://go-review.googlesource.com/c/go/+/174299
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

* runtime: account for callbacks in checkdead on Windows

When a callback runs on a different thread in Windows, as in the
runtime package test TestCallbackInAnotherThread, it will use the
extra M. That can cause the test in checkdead to fail incorrectly.
Check whether there actually is an extra M before expecting it.

I think this is a general problem unrelated to timers. I think the test
was passing previously because the timer goroutine was using an M.
But I haven't proved that. This change seems correct, and it avoids
the test failure when using the new timers on Windows.

Updates #27707

Change-Id: Ieb31c04ff0354d6fae7e173b59bcfadb8b0464cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/174037
Reviewed-by: Keith Randall <khr@golang.org>

* cmd,runtime: enable cgo for openbsd/arm64

Updates #31656.

Change-Id: Ide6f829282fcdf20c67998b766a201a6a92c3035
Reviewed-on: https://go-review.googlesource.com/c/go/+/174132
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

* cmd/compile: evaluate map initializers incrementally

For the code:

m := map[int]int {
  a(): b(),
  c(): d(),
  e(): f(),
}

We used to do:

t1 := a()
t2 := b()
t3 := c()
t4 := d()
t5 := e()
t6 := f()
m := map[int]int{}
m[t1] = t2
m[t3] = t4
m[t5] = t6

After this CL we do:

m := map[int]int{}
t1 := a()
t2 := b()
m[t1] = t2
t3 := c()
t4 := d()
m[t3] = t4
t5 := e()
t6 := f()
m[t5] = t6

Ordering the initialization this way limits the lifetime of the
temporaries involved.  In particular, for large maps the number of
simultaneously live temporaries goes from ~2*len(m) to ~2. This change
makes the compiler (regalloc, mostly) a lot happier. The compiler runs
faster and uses a lot less memory.

For #26546, changes compile time of a big map from 8 sec to 0.5 sec.

Fixes #26552

Update #26546

Change-Id: Ib7d202dead3feaf493a464779fd9611c63fcc25f
Reviewed-on: https://go-review.googlesource.com/c/go/+/174417
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

* cmd/go: add test of $GONOPROXY, $GONOSUMDB behavior

Change-Id: I8a4917ce14ea22d5991226e485d43a9c9312950e
Reviewed-on: https://go-review.googlesource.com/c/go/+/174219
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

* encoding/json: fix Unmarshal hang on recursive pointers

indirect walks down v until it gets to a non-pointer. But it does not
handle the case when v is a pointer to itself, like in:

	var v interface{}
	v = &v
	Unmarshal(b, v)

So just stop immediately if we see v is a pointer to itself.

Fixes #31740

Change-Id: Ie396264119e24d70284cd9bf76dcb2050babb069
Reviewed-on: https://go-review.googlesource.com/c/go/+/174337
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* runtime: do not use heap arena hints on wasm

The address space of WebAssembly's linear memory is contiguous, so
requesting specific addresses is not supported. Do not use heap arena
hints so we do not have unused memory ranges.

This fixes go1 benchmarks on wasm which ran out of memory since
https://golang.org/cl/170950.

Change-Id: I70115b18dbe43abe16dd5f57996343d97bf94760
Reviewed-on: https://go-review.googlesource.com/c/go/+/174203
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

* cmd/internal/obj/wasm: cache SP in a local

We use Wasm global variables extensively for simulating
registers, especially SP. V8 does not handle global variables
efficiently.

This CL reduces global variable accesses by caching the global SP
in a local variable in each function. The local cache is set on
function entry and updated after each call (where the stack could
have moved). Within a function, the SP access will use the local
variable.

Supersedes https://golang.org/cl/173979.

Running on Chrome Version 73.0.3683.103 on darwin/amd64:

name                   old time/op    new time/op     delta
BinaryTree17              15.3s ± 2%      14.5s ± 3%   -5.20%  (p=0.000 n=9+10)
Fannkuch11                8.91s ± 2%      9.48s ± 2%   +6.41%  (p=0.000 n=9+10)
FmtFprintfEmpty           197ns ± 5%      165ns ± 3%  -16.09%  (p=0.000 n=9+8)
FmtFprintfString          354ns ± 8%      325ns ± 7%   -8.33%  (p=0.001 n=10+10)
FmtFprintfInt             400ns ± 4%      368ns ± 6%   -8.01%  (p=0.000 n=10+10)
FmtFprintfIntInt          618ns ± 3%      587ns ± 6%   -4.97%  (p=0.001 n=10+10)
FmtFprintfPrefixedInt     637ns ± 4%      606ns ± 4%   -4.88%  (p=0.000 n=10+10)
FmtFprintfFloat           965ns ± 7%      898ns ± 4%   -6.97%  (p=0.000 n=10+10)
FmtManyArgs              2.34µs ± 1%     2.24µs ± 3%   -4.40%  (p=0.000 n=9+10)
GobDecode                29.8ms ± 3%     28.8ms ± 6%   -3.60%  (p=0.006 n=9+10)
GobEncode                20.5ms ± 8%     17.6ms ± 3%  -14.32%  (p=0.000 n=10+10)
Gzip                      714ms ± 3%      718ms ± 8%     ~     (p=0.971 n=10+10)
Gunzip                    148ms ± 3%      136ms ± 3%   -7.99%  (p=0.000 n=10+9)
HTTPClientServer          219µs ± 3%      215µs ± 4%     ~     (p=0.190 n=10+10)
JSONEncode               35.1ms ± 2%     31.8ms ±13%   -9.52%  (p=0.002 n=10+10)
JSONDecode                220ms ± 3%      207ms ± 5%   -5.87%  (p=0.000 n=10+10)
Mandelbrot200            5.22ms ± 1%     5.11ms ± 4%   -2.11%  (p=0.027 n=8+10)
GoParse                  17.2ms ± 6%     16.1ms ± 5%   -6.63%  (p=0.000 n=10+9)
RegexpMatchEasy0_32       375ns ± 3%      340ns ± 3%   -9.25%  (p=0.000 n=10+10)
RegexpMatchEasy0_1K      2.70µs ± 3%     2.65µs ± 4%     ~     (p=0.118 n=10+10)
RegexpMatchEasy1_32       341ns ± 2%      305ns ± 4%  -10.62%  (p=0.000 n=9+10)
RegexpMatchEasy1_1K      3.20µs ± 3%     2.99µs ± 3%   -6.35%  (p=0.000 n=10+10)
RegexpMatchMedium_32      520ns ± 3%      501ns ± 4%   -3.64%  (p=0.002 n=9+10)
RegexpMatchMedium_1K      145µs ± 7%      128µs ± 3%  -11.57%  (p=0.000 n=9+10)
RegexpMatchHard_32       7.88µs ± 3%     7.01µs ± 5%  -10.97%  (p=0.000 n=10+10)
RegexpMatchHard_1K        237µs ± 5%      207µs ± 4%  -12.71%  (p=0.000 n=9+10)
Revcomp                   2.34s ± 1%      2.31s ± 5%     ~     (p=0.230 n=7+10)
Template                  261ms ± 7%      246ms ± 5%   -5.93%  (p=0.007 n=10+10)
TimeParse                1.47µs ± 3%     1.39µs ± 5%   -5.75%  (p=0.000 n=9+10)
TimeFormat               1.52µs ± 3%     1.43µs ± 4%   -6.42%  (p=0.000 n=8+10)

name                   old speed      new speed       delta
GobDecode              25.7MB/s ± 3%   26.7MB/s ± 5%   +3.77%  (p=0.006 n=9+10)
GobEncode              37.5MB/s ± 8%   43.7MB/s ± 3%  +16.61%  (p=0.000 n=10+10)
Gzip                   27.2MB/s ± 3%   27.0MB/s ± 7%     ~     (p=0.971 n=10+10)
Gunzip                  131MB/s ± 3%    142MB/s ± 5%   +8.07%  (p=0.000 n=10+10)
JSONEncode             55.2MB/s ± 2%   61.2MB/s ±12%  +10.80%  (p=0.002 n=10+10)
JSONDecode             8.84MB/s ± 3%   9.39MB/s ± 5%   +6.28%  (p=0.000 n=10+10)
GoParse                3.37MB/s ± 6%   3.61MB/s ± 5%   +7.09%  (p=0.000 n=10+9)
RegexpMatchEasy0_32    85.3MB/s ± 3%   94.0MB/s ± 3%  +10.20%  (p=0.000 n=10+10)
RegexpMatchEasy0_1K     379MB/s ± 3%    387MB/s ± 4%     ~     (p=0.123 n=10+10)
RegexpMatchEasy1_32    93.9MB/s ± 2%  105.1MB/s ± 4%  +11.96%  (p=0.000 n=9+10)
RegexpMatchEasy1_1K     320MB/s ± 3%    342MB/s ± 3%   +6.79%  (p=0.000 n=10+10)
RegexpMatchMedium_32   1.92MB/s ± 2%   2.00MB/s ± 3%   +3.94%  (p=0.001 n=9+10)
RegexpMatchMedium_1K   7.09MB/s ± 6%   8.01MB/s ± 3%  +13.00%  (p=0.000 n=9+10)
RegexpMatchHard_32     4.06MB/s ± 3%   4.56MB/s ± 5%  +12.38%  (p=0.000 n=10+10)
RegexpMatchHard_1K     4.32MB/s ± 4%   4.96MB/s ± 4%  +14.60%  (p=0.000 n=9+10)
Revcomp                 109MB/s ± 1%    110MB/s ± 5%     ~     (p=0.219 n=7+10)
Template               7.44MB/s ± 8%   7.91MB/s ± 5%   +6.30%  (p=0.007 n=10+10)

Change-Id: I5828cf6b23ce104c02addc2642aba48dd6c48aab
Reviewed-on: https://go-review.googlesource.com/c/go/+/174062
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

* cmd/go/internal/modfetch: fix concurrent read/write race in modfetch

On Windows systems, the failure rate for cmd/go's TestScript/mod_concurrent
is somewhere around 3-10% without this change. With the change, I have yet
to see a failure.

Fixes #31744.

Change-Id: Ib321ebb9556dd8438086cf329dfa083a9e051732
Reviewed-on: https://go-review.googlesource.com/c/go/+/174439
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* encoding/csv: add a Fuzz function

Adds a sample Fuzz test function to package encoding/csv based on
https://github.com/dvyukov/go-fuzz-corpus/blob/master/csv/main.go

Updates #19109
Updates #31309

Change-Id: Ieb0cb6caa1df72dbb7e29df4bdeed0bfa91187d3
Reviewed-on: https://go-review.googlesource.com/c/go/+/174302
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go: say to confirm import path when it's not found

Fixes #31366.

Change-Id: Ief26f53e7fe94bedb7db79d3d7130c4cdcec4281
Reviewed-on: https://go-review.googlesource.com/c/go/+/174179
Run-TryBot: Jay Conrod <jayconrod@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* html: add a Fuzz function

Adds a sample Fuzz test function to package html based on
https://github.com/dvyukov/go-fuzz-corpus/blob/master/stdhtml/main.go

Updates #19109
Updates #31309

Change-Id: I8c49fff8f70fc8a8813daf1abf0044752003adbb
Reviewed-on: https://go-review.googlesource.com/c/go/+/174301
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/dist: disable cgo for darwin/386

Fixes #31751

Change-Id: Id002f14557a34accc3597cb1b9a42e838a027da4
Reviewed-on: https://go-review.googlesource.com/c/go/+/174497
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* runtime: implement pthread functions for darwin/arm64

They were not needed when Go only produced binaries with cgo suppport.
Now that Go is about to run self-hosted on iOS we do need these.

Updates #31722

Change-Id: If233aa2b31edc7b1c2dcac68974f9fba0604f9a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/174300
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/link: add .go.buildinfo in XCOFF symbol table

.go.buildinfo must be added to the symbol table on AIX. Otherwise, ld
won't be able to handle its relocations.

This patch also make ".data" the default section for all symbols inside
the data segment.

Change-Id: I83ac2bf1050e0ef6ef9c96ff793efd4ddc8e98d7
Reviewed-on: https://go-review.googlesource.com/c/go/+/174298
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* all: add new GOOS=illumos, split out of GOOS=solaris

Like GOOS=android which implies the "linux" build tag, GOOS=illumos
implies the "solaris" build tag. This lets the existing ecosystem of
packages still work on illumos, but still permits packages to start
differentiating between solaris and illumos.

Fixes #20603

Change-Id: I8f4eabf1a66060538dca15d7658c1fbc6c826622
Reviewed-on: https://go-review.googlesource.com/c/go/+/174457
Run-TryBot: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* runtime: fix data sizes for res_search results

The return values are 32 bit, not 64 bit.

I don't think this would be the cause of any problems, but
it can't hurt to fix it.

Change-Id: Icdd50606360ab9d74070271f9d1721d5fe640bc7
Reviewed-on: https://go-review.googlesource.com/c/go/+/174518
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go/internal/modcmd: allow mod download without go.mod

Fixes #29522

Change-Id: I48f3a945d24c23c7c7ef5c7f1fe5046b6b2898e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/157937
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

* all: refer to map elements as elements instead of values

The spec carefully and consistently uses "key" and "element"
as map terminology. The implementation, not so much.

This change attempts to make the implementation consistently
hew to the spec's terminology. Beyond consistency, this has
the advantage of avoid some confusion and naming collisions,
since v and value are very generic and commonly used terms.

I believe that I found all everything, but there are a lot of
non-obvious places for these to hide, and grepping for them is hard.
Hopefully this change changes enough of them that we will start using
elem going forward. Any remaining hidden cases can be removed ad hoc
as they are discovered.

The only externally-facing part of this change is in package reflect,
where there is a minor doc change and a function parameter name change.

Updates #27167

Change-Id: I2f2d78f16c360dc39007b9966d5c2046a29d3701
Reviewed-on: https://go-review.googlesource.com/c/go/+/174523
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* encoding/gob: adding missing fuzz skip to one of the fuzz tests

It's slow & often times out randomly on longtest builders. Not useful.

Fixes #31517

Change-Id: Icedbb0c94fbe43d04e8b47d5785ac61c5e2d8750
Reviewed-on: https://go-review.googlesource.com/c/go/+/174522
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/dist: set the default external linker on platforms without gcc

The go tool already sets -extld to the appropriate compiler. This
CL changes cmd/dist to do the same, to fix bootstrapping on platforms
that only have clang (Android and iOS).

Updates #31722

Change-Id: I8a4fd227f85a768053a8946198eab68bbbdf9ae5
Reviewed-on: https://go-review.googlesource.com/c/go/+/174305
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/dist: detect GOHOSTARCH on iOS

cmd/dist defaults to GOHOSTARCH=amd64 on darwin because no other
darwin host could build Go. With the upcoming self-hosted iOS
builders, GOHOSTARCH=arm64 is also possible.

Updates #31722

Change-Id: I9af47d9f8c57ea45475ce498acefbfe6bf4815b9
Reviewed-on: https://go-review.googlesource.com/c/go/+/174306
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go: derive executable name from package path in 'go run'

Change name of temporary executable on go run . to directory name.
Fixes #31571

Change-Id: I0a0ce74154e76205bb43805c95bd7fb8fd2dfd01
GitHub-Last-Rev: e0964983e18a1d45b55f7098c7489059708c7e5e
GitHub-Pull-Request: golang/go#31614
Reviewed-on: https://go-review.googlesource.com/c/go/+/173297
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

* time: look for zoneinfo.zip in GOROOT

The zoneinfo.zip file will be in the $GOROOT in self-hsoted builds
on iOS.

Updates #31722

Change-Id: I991fae92e3dc50581b099a2d8901aed36ecc7cef
Reviewed-on: https://go-review.googlesource.com/c/go/+/174310
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/go: query modules in parallel

Refactor modload.QueryPackage and modload.QueryPattern to share code.

Fine-tune error reporting and make it consistent between QueryPackage and QueryPattern.

Expand tests for pattern errors.

Update a TODO in modget/get.go and add a test case that demonstrates it.

Updates #26232

Change-Id: I900ca8de338ef9a51b7f85ed93d8bcf837621646
Reviewed-on: https://go-review.googlesource.com/c/go/+/173017
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

* net/http: make Server return 501 for unsupported transfer-encodings

Ensures that our HTTP/1.X Server properly responds
with a 501 Unimplemented as mandated by the spec at
RFC 7230 Section 3.3.1, which says:
    A server that receives a request message with a
    transfer coding it does not understand SHOULD
    respond with 501 (Unimplemented).

Fixes #30710

Change-Id: I096904e6df053cd1e4b551774cc27523ff3d09f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/167017
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go,cmd/internal/sys,cmd/link: skip Go build ids for externally linked tools

cmd/go already skips build ids on Android where buildmode=pie is
forced. Expand the check to all externally linked tools.

Necessary for self-hosted iOS builds where PIE is not forced but
external linking is.

Updates #31722

Change-Id: Iad796a9411a37eb0c44d365b70a3c5907537e461
Reviewed-on: https://go-review.googlesource.com/c/go/+/174307
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

* cmd/go/internal/modfetch/codehost: disable fetch of server-resolved commit hash

We cannot rely on the server to filter out the refs we don't want
(we only want refs/heads/* and refs/tags/*), so do not give it
the full hash.

Fixes #31191.

Change-Id: If1208c35954228aa6e8734f8d5f1725d0ec79c87
Reviewed-on: https://go-review.googlesource.com/c/go/+/174517
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/compile: remove dynamic entry handling from sinit/maplit

The order pass now handles all the dynamic entries.

Update #26552

Followup to CL 174417

Change-Id: Ie924cadb0e0ba36c423868f654f13040100b44c6
Reviewed-on: https://go-review.googlesource.com/c/go/+/174498
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

* os: fix tests on self-hosted Go builds

Updates #31722

Change-Id: I467bb2539f993fad642abf96388a58a263fbe007
Reviewed-on: https://go-review.googlesource.com/c/go/+/174311
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/asm: reject BSWAPW on amd64

Since BSWAP operation on 16-bit registers is undefined,
forbid the usage of BSWAPW. Users should rely on XCHGB instead.

This behavior is consistent with what GAS does.

Fixes #29167

Change-Id: I3b31e3dd2acfd039f7564a1c17e6068617bcde8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/174312
Run-TryBot: Iskander Sharipov <quasilyte@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/compile: fix line numbers for index panics

In the statement x = a[i], the index panic should appear to come from
the line number of the '['. Previous to this CL we sometimes used the
line number of the '=' instead.

Fixes #29504

Change-Id: Ie718fd303c1ac2aee33e88d52c9ba9bcf220dea1
Reviewed-on: https://go-review.googlesource.com/c/go/+/174617
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/compile: add signed divisibility rules

"Division by invariant integers using multiplication" paper
by Granlund and Montgomery contains a method for directly computing
divisibility (x%c == 0 for c constant) by means of the modular inverse.
The method is further elaborated in "Hacker's Delight" by Warren Section 10-17

This general rule can compute divisibilty by one multiplication, and add
and a compare for odd divisors and an additional rotate for even divisors.

To apply the divisibility rule, we must take into account
the rules to rewrite x%c = x-((x/c)*c) and (x/c) for c constant on the first
optimization pass "opt".  This complicates the matching as we want to match
only in the cases where the result of (x/c) is not also needed.
So, we must match on the expanded form of (x/c) in the expression x == c*(x/c)
in the "late opt" pass after common subexpresion elimination.

Note, that if there is an intermediate opt pass introduced in the future we
could simplify these rules by delaying the magic division rewrite to "late opt"
and matching directly on (x/c) in the intermediate opt pass.

On amd64, the divisibility check is 30-45% faster.

name                     old time/op  new time/op  delta`
DivisiblePow2constI64-4  0.83ns ± 1%  0.82ns ± 0%     ~     (p=0.079 n=5+4)
DivisibleconstI64-4      2.68ns ± 1%  1.87ns ± 0%  -30.33%  (p=0.000 n=5+4)
DivisibleWDivconstI64-4  2.69ns ± 1%  2.71ns ± 3%     ~     (p=1.000 n=5+5)
DivisiblePow2constI32-4  1.15ns ± 1%  1.15ns ± 0%     ~     (p=0.238 n=5+4)
DivisibleconstI32-4      2.24ns ± 1%  1.20ns ± 0%  -46.48%  (p=0.016 n=5+4)
DivisibleWDivconstI32-4  2.27ns ± 1%  2.27ns ± 1%     ~     (p=0.683 n=5+5)
DivisiblePow2constI16-4  0.81ns ± 1%  0.82ns ± 1%     ~     (p=0.135 n=5+5)
DivisibleconstI16-4      2.11ns ± 2%  1.20ns ± 1%  -42.99%  (p=0.008 n=5+5)
DivisibleWDivconstI16-4  2.23ns ± 0%  2.27ns ± 2%   +1.79%  (p=0.029 n=4+4)
DivisiblePow2constI8-4   0.81ns ± 1%  0.81ns ± 1%     ~     (p=0.286 n=5+5)
DivisibleconstI8-4       2.13ns ± 3%  1.19ns ± 1%  -43.84%  (p=0.008 n=5+5)
DivisibleWDivconstI8-4   2.23ns ± 1%  2.25ns ± 1%     ~     (p=0.183 n=5+5)

Fixes #30282
Fixes #15806

Change-Id: Id20d78263a4fdfe0509229ae4dfa2fede83fc1d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/173998
Run-TryBot: Brian Kessler <brian.m.kessler@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* cmd/go: make get -u upgrade only modules providing packages

Currently, 'go get -u' upgrades modules matching command line
arguments and any modules they transitively require. 'go get -u' with
no positional arguments upgrades all modules transitively required by
the main module. This usually adds a large number of indirect
requirements, which is surprising to users.

With this change, 'go get' will load packages specified by
its arguments using a similar process to other commands
('go build', etc). Only modules providing packages will be upgraded.

'go get -u' now upgrades modules providing packages transitively
imported by the command-line arguments. 'go get -u' without arguments
will only upgrade modules needed by the package in the current
directory.

'go get -m' will load all packages within a module. 'go get -m -u'
without arguments will upgrade modules needed by the main module. It
is equivalent to 'go get -u all'. Neither command will upgrade modules
that are required but not used.

Note that 'go get -m' and 'go get -d' both download modules in order
to load packages.

Fixes #26902

Change-Id: I2bad686b3ca8c9de985a81fb42b16a36bb4cc3ea
Reviewed-on: https://go-review.googlesource.com/c/go/+/174099
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

* syscall: on wasm, do not use typed array asynchronously

The underlying buffer of a typed array becomes invalid as soon as we
grow the WebAssembly memory, which can happen at any time while Go code
runs. This is a known limitation, see https://golang.org/cl/155778.

As a consequence, using a typed array with one of the asynchronous
read/write operations of Node.js' fs module is dangerous, since it may
become invalid while the asynchronous operation has not finished yet.
The result of this situation is most likely undefined.

I am not aware of any nice solution to this issue, so this change adds
a workaround of using an additional typed array which is not backed by
WebAssembly memory and copying the bytes between the two typed arrays.

Maybe WebAssembly will come up with a better solution in the future.

Fixes #31702.

Change-Id: Iafc2a0fa03c81db414520bd45a1a17c00080b61e
Reviewed-on: https://go-review.googlesource.com/c/go/+/174304
Run-TryBot: Richard Musiol <neelance@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

* net/http: add Transport.ReadBufferSize and WriteBufferSize

Previously transport was using the hardcoded bufio.defaultBufSize
(4096), limiting throughput and increasing cpu usage when uploading or
downloading large files.

Add options to allow users to configure the buffer sizes as needed.

I tested the maximum benefit of this change by uploading data from
/dev/zero to a server discarding the bytes. Here is an example upload
using the default buffer size:

$ time ./upload 10 https://localhost:8000/
Uploaded 10.00g in 25.13 seconds (407.49m/s)

real	0m25.135s
user	0m5.167s
sys	0m11.643s

With this change, using 128k buffer size:

$ time ./upload 10 https://localhost:8000/
Uploaded 10.00g in 7.93 seconds (1291.51m/s)

real	0m7.935s
user	0m4.517s
sys	0m2.603s

In real world usage the difference will be smaller, depending on the
local and remote storage and the network.

See https://github.com/nirs/http-bench for more info.

Fixes #22618

Change-Id: Iac99ed839c7b95d6dc66602ba8fe1fc5b500c47c
Reviewed-on: https://go-review.googlesource.com/c/go/+/76410
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* net/http: make Transport.MaxConnsPerHost work for HTTP/2

Treat HTTP/2 connections as an ongoing persistent connection. When we
are told there is no cached connections, cleanup the associated
connection and host connection count.

Fixes #27753

Change-Id: I6b7bd915fc7819617cb5d3b35e46e225c75eda29
Reviewed-on: https://go-review.googlesource.com/c/go/+/140357
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* internal/cpu: add detection for the new ECDSA and EDDSA capabilities on s390x

This CL will check for the Message-Security-Assist Extension 9 facility
which enables the KDSA instruction.

Change-Id: I659aac09726e0999ec652ef1f5983072c8131a48
Reviewed-on: https://go-review.googlesource.com/c/go/+/174529
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* net: set DNSError.IsTemporary from addrinfoErrno errors

Today it is not possible (AFAICT) to detect if a DNSError if of type EAI_AGAIN, i.e. if it is something temporary that should be retried. This information is available inside addrinfoErrno but when the DNSError is created this information is lost.

This PR fixes this so that the addinfoErrno.Temporary information is added to DNSError as well. With that a user who gets a DNSError can check now is its a temporary error (for errors that resulted from a addrinfoErrno this is EAI_AGAIN).

Change-Id: I64badb2ebd904e41fc2e0755416f7f32560534d8
GitHub-Last-Rev: ced7238a6597039fb23f36f372bd1cf33d60d4a6
GitHub-Pull-Request: golang/go#31676
Reviewed-on: https://go-review.googlesource.com/c/go/+/174557
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* os,time: fix tests on iOS

When fixing tests for for self-hosted iOS builds, I
broke hosted builds.

Updates #31722

Change-Id: Id4e7d234fbd86cb2d29d320d75f4441efd663d12
Reviewed-on: https://go-review.googlesource.com/c/go/+/174698
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* test: enable more memcombine tests for ppc64le

This enables more of the testcases in memcombine for ppc64le,
and adds more detail to some existing.

Change-Id: Ic522a1175bed682b546909c96f9ea758f8db247c
Reviewed-on: https://go-review.googlesource.com/c/go/+/174737
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* runtime: change the span allocation policy to first-fit

This change modifies the treap implementation to be address-ordered
instead of size-ordered, and further augments it so it may be used for
allocation. It then modifies the find method to implement a first-fit
allocation policy.

This change to the treap implementation consequently makes it so that
spans are scavenged in highest-address-first order without any
additional changes to the scavenging code. Because the treap itself is
now address ordered, and the scavenging code iterates over it in
reverse, the highest address is now chosen instead of the largest span.

This change also renames the now wrongly-named "scavengeLargest" method
on mheap to just "scavengeLocked" and also fixes up logic in that method
which made assumptions about size.

For #30333.

Change-Id: I94b6f3209211cc1bfdc8cdaea04152a232cfbbb4
Reviewed-on: https://go-review.googlesource.com/c/go/+/164101
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

* go/internal/gccgoimporter: skip new test with aliases with old gccgo

Add the issue31540 test to the list of tests that needs to be skipped
with old copies of gccgo. Along the way, add an explicit field to the
importer test struct that can be used to tag the test (as opposed to
having special cases by name in the test routine), so as to make it
easier to remember to tag testcases correctly.

Fixes #31764.

Change-Id: Ib9d98fea2df8ce0b51e5a886fb2c4acd6db490ff
Reviewed-on: https://go-review.googlesource.com/c/go/+/174738
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/compile/internal/ppc64: improve naming for ginsnop2

This is a follow up from a review comment at the end of the last
Go release, to provide a more meaningful name for ginsnop2.

Updates #30475

Change-Id: Ice9efd763bf2204a9e8c55ae230d3e8a80210108
Reviewed-on: https://go-review.googlesource.com/c/go/+/174757
Run-TryBot: Lynn Boger <laboger@linux.vnet.ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

* index/suffixarray: add 32-bit implementation

The original index/suffixarray used 32-bit ints on 64-bit machines,
because that's what 'int' meant in Go at the time. When we changed
the meaning of int, that doubled the space overhead of suffix arrays
for all uses, even though the vast majority of them describe less
than 2 GB of text.

The space overhead of a suffix array compared to the text is not
insignificant: there's a big difference for many uses between 4X and 8X.

This CL adjusts names in qsufsort.go so that a global search and
replace s/32/64/g produces a working 64-bit implementation,
and then it modifies suffixarray.go to choose between the 32-bit
and 64-bit implementation as appropriate depending on the input size.
The 64-bit implementation is generated by 'go generate'.

This CL also restructures the benchmarks, to test different
input sizes, different input texts, and 32-bit vs 64-bit.

The serialized form uses varint-encoded numbers and is unchanged,
so on-disk suffix arrays written by older versions of Go will be
readable by this version, and vice versa.

The 32-bit version runs a up to 17% faster than the 64-bit version
on real inputs, but more importantly it uses 50% less memory.

I have a followup CL that also implements a faster algorithm
on top of these improvements, but these are a good first step.

name                                  64-bit speed   32-bit speed    delta
New/text=opticks/size=100K/bits=*-12  4.44MB/s ± 0%  4.64MB/s ± 0%   +4.41%  (p=0.008 n=5+5)
New/text=opticks/size=500K/bits=*-12  3.70MB/s ± 1%  3.82MB/s ± 0%   +3.30%  (p=0.008 n=5+5)
New/text=go/size=100K/bits=*-12       4.40MB/s ± 0%  4.61MB/s ± 0%   +4.82%  (p=0.008 n=5+5)
New/text=go/size=500K/bits=*-12       3.66MB/s ± 0%  3.77MB/s ± 0%   +3.01%  (p=0.016 n=4+5)
New/text=go/size=1M/bits=*-12         3.29MB/s ± 0%  3.55MB/s ± 0%   +7.90%  (p=0.016 n=5+4)
New/text=go/size=5M/bits=*-12         2.25MB/s ± 1%  2.65MB/s ± 0%  +17.81%  (p=0.008 n=5+5)
New/text=go/size=10M/bits=*-12        1.82MB/s ± 0%  2.09MB/s ± 1%  +14.36%  (p=0.008 n=5+5)
New/text=go/size=50M/bits=*-12        1.35MB/s ± 0%  1.51MB/s ± 1%  +12.33%  (p=0.008 n=5+5)
New/text=zero/size=100K/bits=*-12     3.42MB/s ± 0%  3.32MB/s ± 0%   -2.74%  (p=0.000 n=5+4)
New/text=zero/size=500K/bits=*-12     3.00MB/s ± 1%  2.97MB/s ± 0%   -1.13%  (p=0.016 n=5+4)
New/text=zero/size=1M/bits=*-12       2.81MB/s ± 0%  2.78MB/s ± 2%     ~     (p=0.167 n=5+5)
New/text=zero/size=5M/bits=*-12       2.46MB/s ± 0%  2.53MB/s ± 0%   +3.18%  (p=0.008 n=5+5)
New/text=zero/size=10M/bits=*-12      2.35MB/s ± 0%  2.42MB/s ± 0%   +2.98%  (p=0.016 n=4+5)
New/text=zero/size=50M/bits=*-12      2.12MB/s ± 0%  2.18MB/s ± 0%   +3.02%  (p=0.008 n=5+5)
New/text=rand/size=100K/bits=*-12     6.98MB/s ± 0%  7.22MB/s ± 0%   +3.38%  (p=0.016 n=4+5)
New/text=rand/size=500K/bits=*-12     5.53MB/s ± 0%  5.64MB/s ± 0%   +1.92%  (p=0.008 n=5+5)
New/text=rand/size=1M/bits=*-12       4.62MB/s ± 1%  5.06MB/s ± 0%   +9.61%  (p=0.008 n=5+5)
New/text=rand/size=5M/bits=*-12       3.09MB/s ± 0%  3.43MB/s ± 0%  +10.94%  (p=0.016 n=4+5)
New/text=rand/size=10M/bits=*-12      2.68MB/s ± 0%  2.95MB/s ± 0%  +10.39%  (p=0.008 n=5+5)
New/text=rand/size=50M/bits=*-12      1.92MB/s ± 0%  2.06MB/s ± 1%   +7.41%  (p=0.008 n=5+5)
SaveRestore/bits=*-12                  243MB/s ± 1%   259MB/s ± 0%   +6.68%  (p=0.000 n=9+10)

name                               64-bit alloc/op  32-bit alloc/op  delta
New/text=opticks/size=100K/bits=*-12    1.62MB ± 0%    0.81MB ± 0%  -50.00%  (p=0.000 n=5+4)
New/text=opticks/size=500K/bits=*-12    8.07MB ± 0%    4.04MB ± 0%  -49.89%  (p=0.008 n=5+5)
New/text=go/size=100K/bits=*-12         1.62MB ± 0%    0.81MB ± 0%  -50.00%  (p=0.008 n=5+5)
New/text=go/size=500K/bits=*-12         8.07MB ± 0%    4.04MB ± 0%  -49.89%  (p=0.029 n=4+4)
New/text=go/size=1M/bits=*-12           16.1MB ± 0%     8.1MB ± 0%  -49.95%  (p=0.008 n=5+5)
New/text=go/size=5M/bits=*-12           80.3MB ± 0%    40.2MB ± 0%     ~     (p=0.079 n=4+5)
New/text=go/size=10M/bits=*-12           160MB ± 0%      80MB ± 0%  -50.00%  (p=0.008 n=5+5)
New/text=go/size=50M/bits=*-12           805MB ± 0%     402MB ± 0%  -50.06%  (p=0.029 n=4+4)
New/text=zero/size=100K/bits=*-12       3.02MB ± 0%    1.46MB ± 0%     ~     (p=0.079 n=4+5)
New/text=zero/size=500K/bits=*-12       19.7MB ± 0%     8.7MB ± 0%  -55.98%  (p=0.008 n=5+5)
New/text=zero/size=1M/bits=*-12         39.0MB ± 0%    19.7MB ± 0%  -49.60%  (p=0.000 n=5+4)
New/text=zero/size=5M/bits=*-12          169MB ± 0%      85MB ± 0%  -49.46%  (p=0.029 n=4+4)
New/text=zero/size=10M/bits=*-12         333MB ± 0%     169MB ± 0%  -49.43%  (p=0.000 n=5+4)
New/text=zero/size=50M/bits=*-12        1.63GB ± 0%    0.74GB ± 0%  -54.61%  (p=0.008 n=5+5)
New/text=rand/size=100K/bits=*-12       1.61MB ± 0%    0.81MB ± 0%  -50.00%  (p=0.000 n=5+4)
New/text=rand/size=500K/bits=*-12       8.07MB ± 0%    4.04MB ± 0%  -49.89%  (p=0.000 n=5+4)
New/text=rand/size=1M/bits=*-12         16.1MB ± 0%     8.1MB ± 0%  -49.95%  (p=0.029 n=4+4)
New/text=rand/size=5M/bits=*-12         80.7MB ± 0%    40.3MB ± 0%  -50.06%  (p=0.008 n=5+5)
New/text=rand/size=10M/bits=*-12         161MB ± 0%      81MB ± 0%  -50.03%  (p=0.008 n=5+5)
New/text=rand/size=50M/bits=*-12         806MB ± 0%     403MB ± 0%  -50.00%  (p=0.016 n=4+5)
SaveRestore/bits=*-12                   9.47MB ± 0%    5.28MB ± 0%  -44.29%  (p=0.000 n=9+8)

https://perf.golang.org/search?q=upload:20190126.1+|+bits:64+vs+bits:32

Fixes #6816.

Change-Id: Ied2fbea519a202ecc43719debcd233344ce38847
Reviewed-on: https://go-review.googlesource.com/c/go/+/174097
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* runtime: look for idle p to run current goroutine when switching to GC or traceReader

This repairs one of the several causes of pauses uncovered
by a GC microbenchmark.  A pause can occur when a goroutine's
quantum expires "at the same time" a GC is needed.  The
current M switches to running a GC worker, which means that
the amount of available work has expanded by one.  The GC
worker, however, does not call ready, and does not itself
conditionally wake a P (a "normal" thread would do this).

This is also true if M switches to a traceReader.

This is problem 4 in this list:
https://github.com/golang/go/issues/27732#issuecomment-423301252

Updates #27732.

Change-Id: I6905365cac8504cde6faab2420f4421536551f0b
Reviewed-on: https://go-review.googlesource.com/c/go/+/146817
Run-TryBot: David Chase <drchase@google.com>
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Reviewed-by: Austin Clements <austin@google.com>

* cmd/go/internal/modfetch/codehost: fix pseudoversions for non-semver tags and tags on other branches

Pseudoversion determination depends in part on the results from gitRepo.RecentTag, which currently invokes:

git describe --first-parent --always --abbrev=0 --match <prefix>v[0-9]*.[0-9]*.[0-9]* --tags <rev>

The comment at https://github.com/golang/go/issues/27171#issuecomment-470134255 describes some problems with the current approach.

One problem is Docker and other repos can have tags that are not valid semver tags but that still match a glob pattern of v[0-9]*.[0-9]*.[0-9]* which are found by 'git describe' but then rejected by cmd/go, and hence those repos currently can end up with v0.0.0 pseudoversions instead of finding a proper semver tag to use as input to building a pseudoversion  (when then causes problems when the v0.0.0 pseudoversion is fed into MVS). An example problematic tag is a date-based tag such as 'v18.06.16', which matches the glob pattern, but is not a valid semver tag (due to the leading 0 in '06').

Issues #31673, #31287, and #27171 also describe problems where the '--first-parent' argument to 'git describe' cause the current approach to miss relevant semver tags that were created on a separate branch and then subsequently merged to master.

In #27171, Bryan described the base tag that is supposed to be used for pseudoversions as:

"It is intended to be the semantically-latest tag that appears on any commit that is a (transitive) parent of the commit with the given hash, regardless of branches. (The pseudo-version is supposed to sort after every version — tagged or otherwise — that came before it, but before the next tag that a human might plausibly want to apply to the branch.)"

This CL solves the glob problem and tags-on-other-branches problem more directly than the current approach: this CL gets the full list of tags that have been merged into the specific revision of interest, and then sorts and filters the results in cmd/go to select the semantically-latest valid semver tag.

Fixes #31673
Fixes #31287
Updates #27171

Change-Id: I7c3e6b46b2b21dd60562cf2893b6bd2afaae61d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/174061
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* cmd/go/internal/get: fix strayed verbose output on stdout

Fixes #31768

Change-Id: I3cc0ebc4be34d7c2d2d4fd655bfd0c2515ff3021
Reviewed-on: https://go-review.googlesource.com/c/go/+/174739
Reviewed-by: Jay Conrod <jayconrod@google.com>
Run-TryBot: Jay Conrod <jayconrod@google.com>
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* cmd/dist: only build exec wrappers when cross compiling

Updates #31722

Change-Id: Ib44b46e628e364fff6eacda2b26541db2f0a4261
Reviewed-on: https://go-review.googlesource.com/c/go/+/174701
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Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* misc/cgo/testcarchive: skip TestExtar on self-hosted iOS

iOS cannot (directly) run shell scripts.

Updates #31722

Change-Id: I69473e9339c50a77338d391c73b4e146bce3fa89
Reviewed-on: https://go-review.googlesource.com/c/go/+/174700
Run-TryBot: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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* strings, bytes: add ToValidUTF8

The newly added functions create a copy of their input with all bytes in
invalid UTF-8 byte sequences mapped to the UTF-8 byte sequence
given as replacement parameter.

Fixes #25805

Change-Id: Iaf65f65b40c0581c6bb000f1590408d6628321d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/142003
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
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Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/go: sort vendor/modules.txt package lists

Right now they are in a deterministic order
but one that depends on the shape of the import graph.
Sort them instead.

Change-Id: Ia0c076a0d6677a511e52acf01f38353e9895dec2
Reviewed-on: https://go-review.googlesource.com/c/go/+/174527
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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* cmd/compile: fix maplit init panics for dynamic entry

golang.org/cl/174498 removes dynamic map entry handling in maplit, by
filtering the static entry only. It panics if it see a dynamic entry.
It relies on order to remove all dynamic entries.

But after recursively call order on the statics, some static entries
become dynamic, e.g OCONVIFACE node:

	type i interface {
		j()
	}
	type s struct{}

	func (s) j() {}

	type foo map[string]i

	var f = foo{
		"1": s{},
	}

To fix it, we recursively call order on each static entry, if it changed
to dynamic, put entry to dynamic then.

Fixes #31777

Change-Id: I1004190ac8f2d1eaa4beb6beab989db74099b025
Reviewed-on: https://go-review.googlesource.com/c/go/+/174777
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

* cmd/go/internal/web: fix log message

The web package is now used for proxy fetches, so its logs shouldn't
start with "Parsing meta tags".

Change-Id: I22a7dce09e3a681544ee4b860f93c63336e547ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/174740
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/compile: disable Go1.13 language features for -lang=go1.12 and below

Fixes   #31747.
Updates #19308.
Updates #12711.
Updates #29008.
Updates #28493.
Updates #19113.

Change-Id: I76d2fdbc7698cc4e0f31b7ae24cbb4d28afbb6a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/174897
Run-TryBot: Robert Griesemer <gri@golang.org>
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* errors: fix comment referencing the Wrapper interface

The Unwrap function performs a type assertion looking for the Wrapper
interface. The method of that interface is called Unwrap but the
interface itself is called Wrapper.

Change-Id: Ie3bf296f93b773d36015bcab2a0e6585d39783c7
GitHub-Last-Rev: 32b1a0c2f8bf8f3eaebf6de252571d82313e86e0
GitHub-Pull-Request: golang/go#31794
Reviewed-on: https://go-review.googlesource.com/c/go/+/174917
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* doc/go1.13: start doc, note macOS, FreeBSD deprecations

For #23011.
For #27619.

Change-Id: Id1f280993ecdfb07a7420926ca1c0f5b7872afbb
Reviewed-on: https://go-review.googlesource.com/c/go/+/174521
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/compile: remove outdate TODO in inl.go

Mid-stack inlining is enable now, see #19348, but we still can not
remove the special case for runtime.heapBits.nextArena, because
runtime.heapBits.next is too complex to be inlined
(cost 96 exceeds budget 80).

Change-Id: I04ea86509074afdc83a3f70d68b8a1a8829763d1
Reviewed-on: https://go-review.googlesource.com/c/go/+/174839
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/go: make modconv test more robust

Change-Id: I3e75201c56779eda1bcd725691c72d384da56f73
Reviewed-on: https://go-review.googlesource.com/c/go/+/174840
Run-TryBot: Baokun Lee <nototon@gmail.com>
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Reviewed-by: Jay Conrod <jayconrod@google.com>

* cmd/go/internal/modload: make 'list -u' consider current pseudoversion

As pointed out by thepudds in #30634, the 'list -u' documentation states that the current version should be considered for upgrade:
The -u flag adds information about available upgrades. When the latest version of a given module is newer than the current one, list -u sets the Module's Update field to information about the newer module.

In go 1.12.4 (and current tip), an older version will be suggested as upgrade to a newer pseudo version.

Updates: #30634

Change-Id: If2c8887198884b8e7ccb3a604908065aa1f1878a
Reviewed-on: https://go-review.googlesource.com/c/go/+/174206
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>

* cmd/dist: don't generate exec wrappers for compatible cross compiles

This change will allow android/arm64 hosts to build for android/arm,
and likewise for iOS.

Updates #31722

Change-Id: Id410bd112abbab585ebb13b61fe4d3a38a1a81fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/174705
Run-TryBot: Elias Naur <mail@eliasnaur.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

* cmd/link: support PIE mode with internal link on linux arm64

This CL improves internal link to provide basic support for cgo and PIE:
1, add support for GOT, PLT and GOTPLT.
2, add support for following ELF relocation types which have been used by std
   packages:
     R_AARCH64_ADR_GOT_PAGE
     R_AARCH64_LD64_GOT_LO12_NC
     R_AARCH64_ADR_PREL_PG_HI21
     R_AARCH64_ADD_ABS_LO12_NC
     R_AARCH64_LDST8_ABS_LO12_NC
     R_AARCH64_LDST32_ABS_LO12_NC
     R_AARCH64_LDST64_ABS_LO12_NC
     R_AARCH64_JUMP26
     R_AARCH64_ABS64
     R_AARCH64_PREL32
     R_AARCH64_PREL64

With this change, Go toolchain can be built in internal linking mode, and
pure Go programs can be built with PIE mode in internal linking mode on arm64.

Updates #10373
The prototype of this CL is contributed by Wei Xiao <wei.xiao@arm.com>

Change-Id: I2253923c69e855fd1524d54def309a961dce6247
Reviewed-on: https://go-review.googlesource.com/c/go/+/163579
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>

* sort: simplify bootstrap

We compile package sort as part of the compiler bootstrap,
to make sure the compiler uses a consistent sort algorithm
no matter what version of Go it is compiled against.
(This matters for elements that compare "equal" but are distinguishab…
@rsc rsc modified the milestones: Go1.14, Backlog Oct 9, 2019
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@bcmills bcmills commented Oct 10, 2019

Just to set expectations: I don't think this will make the 1.14 cycle. (There is too much left to do, and the fixed .netrc support in 1.13 seems to have addressed many of the popular hosting platforms.)

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@arnottcr arnottcr commented Oct 10, 2019

Would it be possible to break up work so that the community can contribute? I am interested in this issue, but unclear if I could meaningfuly help, short of just landing the feature in isolation.

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@bcmills bcmills commented Oct 11, 2019

@arnottcr, I don't know of any way to break it up. The bulk of the work, I think, is making sure that everything works properly in conjunction with the GOPROXY fallback sequence and the package-to-module search sequence.

(Essentially, we currently have a two-dimensional search space, and GOAUTH adds a third dimension to search, so we need to figure out exactly what order to traverse those dimensions to avoid breaking things like the GOPROXY privacy properties.)

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