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cmd/link: tests fail after regenerating testdata on linux_amd64 #8494

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mdempsky opened this issue Aug 7, 2014 · 4 comments

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commented Aug 7, 2014

After cd'ing into cmd/link/testdata and running "make" on Ubuntu 14.04,
running "go test cmd/link" fails:

--- FAIL: TestLinkHello (0.01s)
    prog_test.go:160: testdata/link.hello.darwin.amd64: output file differs at byte 136: have 0xed, want 0xd6
--- FAIL: TestPclntab (0.00s)
    pclntab_test.go:272: pclntab(func0): at pc=+0x0, pcdata#0=-134217728, want -1
    pclntab_test.go:272: pclntab(func1): at pc=+0x0, pcdata#0=-134217728, want -1
    pclntab_test.go:272: pclntab(func2): at pc=+0x0, pcdata#0=-134217728, want -1

The first failure seems to be because hello.6 embeds the source path
"/Users/rsc/g/go/src/cmd/link/testdata/hello.s", which gets copied into the
linker output, and regenerating hello.6 will cause it to contain a new source path
depending on the user's checkout directory name.  This seems easily fixed by changing
cmd/link/testdata/Makefile to pass -trimpath=$PWD to 6a.

The second failure is a bit more surprising though.  Still investigating.
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commented Aug 7, 2014

Comment 1:

Tangentially, http://golang.org/s/go12symtab claims that "nfuncdata" precedes "npcdata",
but cmd/ld and cmd/link put "npcdata" first.
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commented Aug 7, 2014

Comment 2:

CL https://golang.org/cl/123040043 mentions this issue.
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commented Aug 8, 2014

Comment 3:

FWIW, the pclntab_test.go bug was triggered by revision
96917e010ddf9fb400e9e834813a9d3930ae252e.  cmd/link/testdata/pclntab.s does not define a
PCDATA 0 table, but because of the liblink bug fixed in that CL, 6a previously still
emitted a PCDATA table for index 0 that explicitly mapped the entire PC range to -1.
With new liblink, 6a emits a "0" value in index 0, which pclntab_test.go was erroneously
treating as an offset still.  That resulted in trying to parse the symtab header (e.g.,
0xfffffffb, in LE encoding) as a varint, which seems to then coincide with the unwanted
-134217728 value from the error message.
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commented Aug 25, 2014

Comment 4:

This issue was closed by revision 2a679f8.

Status changed to Fixed.

@mdempsky mdempsky added the fixed label Aug 25, 2014

@golang golang locked and limited conversation to collaborators Jun 25, 2016

wheatman added a commit to wheatman/go-akaros that referenced this issue Jun 25, 2018

cmd/link: fix testdata generation
Fixes golang#8494.

LGTM=rsc
R=golang-codereviews, gobot, rsc, evankroske
CC=golang-codereviews
https://golang.org/cl/123040043

wheatman added a commit to wheatman/go-akaros that referenced this issue Jul 9, 2018

cmd/link: fix testdata generation
Fixes golang#8494.

LGTM=rsc
R=golang-codereviews, gobot, rsc, evankroske
CC=golang-codereviews
https://golang.org/cl/123040043

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