8310906: Fix -Wconversion warnings in runtime, oops and some code header files. #14675

coleenp · 2023-06-27T12:41:50Z

This is another version of PR #14659 but I've added a pointer delta function in globalDefinitions.hpp to use for these pointer diff calculations that return int everywhere. If the name is agreeable, I'll fix the other cases of this like this. It's better than raw casts.
Tested with tier1-4.

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JDK-8310906: Fix -Wconversion warnings in runtime, oops and some code header files. (Enhancement - P4)

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Ioi Lam (@iklam - Reviewer) ⚠️ Review applies to 9fed8c89
Frederic Parain (@fparain - Reviewer) ⚠️ Review applies to 9fed8c89

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…der files.

bridgekeeper · 2023-06-27T12:42:56Z

👋 Welcome back coleenp! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2023-06-27T12:45:42Z

@coleenp The following labels will be automatically applied to this pull request:

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mlbridge · 2023-06-27T12:49:27Z

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stefank · 2023-06-27T12:59:59Z

src/hotspot/share/code/codeBlob.inline.hpp

@@ -33,7 +33,7 @@

 inline const ImmutableOopMap* CodeBlob::oop_map_for_slot(int slot, address return_address) const {
  assert(_oop_maps != nullptr, "nope");
-  return _oop_maps->find_map_at_slot(slot, (intptr_t) return_address - (intptr_t) code_begin());
+  return _oop_maps->find_map_at_slot(slot, delta_as_int((intptr_t) return_address, (intptr_t) code_begin()));


Is this the only usage of delta_as_int that operates on intptr_t? If we remove the casts then all usages would operate on pointers. Maybe this is an indication that we only need a pointer_delta_as_int function, to go hand in hand with the other pointer_delta functions?

Hm. Maybe this would be ok. Our original idea was to make it T* not T until this cast. I don't know how many other cases there are that I haven't gotten to yet. But it would eliminate a cast, so that's good (unless these aren't the same). Some instances have ptr - constant that gets promoted I think.
The reason we didn't pick pointer_delta_as_int because pointer_delta has different semantics. pointer_delta insists on positive results.

Taking out that cast does work, so I've fixed that.

pointer_delta has different semantics

Right. That was "recently" added to pointer_delta with JDK-8260046. It begs the question why felt the need to add it there but feel that it is OK to skip it for delta_as_int? Is there some usage of delta_as_int that gives back negative values? Could that call site be changed?

There are sites where the result is negative but this is a good suggestion because it makes the name more consistent. I can change those to plain check_casts.

…enerator.hpp

coleenp · 2023-06-27T23:00:11Z

delta_as_int() could also be: delta2int() ptrdelta2int() ptrdiff2int() ptrsub2int() in the theme of shorter names.
pointer_delta_as_int() ignoring it does something different than pointer_delta() (allows negative returns).
Change them all to check_cast(a - b) - losing identifiable name
ptrdiff_cast(a - b) where int ptrdiff_cast(ptrdiff_t val) { return check(val); }

Brainstorming in a PR. Your suggestions welcome.

…gative case to just do checked_cast.

iklam

LGTM.

iklam · 2023-06-28T16:15:39Z

src/hotspot/share/utilities/globalDefinitions.hpp

-inline int delta_as_int(const volatile T* left, const volatile T* right) {
-  return checked_cast<int>(left - right);
+inline int pointer_delta_as_int(const volatile T* left, const volatile T* right) {
+  return checked_cast<int>(pointer_delta(left, right, sizeof(T)));


For clarity, I think you should add a comment saying the returned value is always non-negative.

done, thanks!

openjdk · 2023-06-28T16:17:23Z

@coleenp This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8310906: Fix -Wconversion warnings in runtime, oops and some code header files.

Reviewed-by: iklam, fparain

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 42 new commits pushed to the master branch:

7fffdb5: 8310405: Linker.Option.firstVariadicArg should specify which index values are valid
b6c789f: 8309140: ResourceHashtable failed "assert(~(_allocation_t[0] | allocation_mask) == (uintptr_t)this) failed: lost resource object"
9f98136: 6956385: URLConnection.getLastModified() leaks file handles for jar:file and file: URLs
46e4ee1: 8310974: NMT: Arena diffs miss the scale
f17bfee: 8311034: Fix typo in javac man page
2ccdd29: 8299825: Move StdoutLog and StderrLog to LogConfiguration
e3f18af: 8311007: jdk/jfr/tool/TestView.java can't find event
08c51f2: 8310920: Fix -Wconversion warnings in command line flags
c2e9485: 8310921: Fix -Wconversion warnings from GenerateOopMap
ef71c32: 8310110: Shenandoah: Trace page sizes
... and 32 more: https://git.openjdk.org/jdk/compare/7db2f08756b0aa1d79cdd2356ed42aa5ab8bc58b...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

fparain

Looks good to me.

coleenp · 2023-06-28T19:41:59Z

Thanks Ioi and Fred and Stefan for suggestions.
/integrate

openjdk · 2023-06-28T19:42:36Z

Going to push as commit 9f46fc2.
Since your change was applied there have been 42 commits pushed to the master branch:

7fffdb5: 8310405: Linker.Option.firstVariadicArg should specify which index values are valid
b6c789f: 8309140: ResourceHashtable failed "assert(~(_allocation_t[0] | allocation_mask) == (uintptr_t)this) failed: lost resource object"
9f98136: 6956385: URLConnection.getLastModified() leaks file handles for jar:file and file: URLs
46e4ee1: 8310974: NMT: Arena diffs miss the scale
f17bfee: 8311034: Fix typo in javac man page
2ccdd29: 8299825: Move StdoutLog and StderrLog to LogConfiguration
e3f18af: 8311007: jdk/jfr/tool/TestView.java can't find event
08c51f2: 8310920: Fix -Wconversion warnings in command line flags
c2e9485: 8310921: Fix -Wconversion warnings from GenerateOopMap
ef71c32: 8310110: Shenandoah: Trace page sizes
... and 32 more: https://git.openjdk.org/jdk/compare/7db2f08756b0aa1d79cdd2356ed42aa5ab8bc58b...master

Your commit was automatically rebased without conflicts.

openjdk · 2023-06-28T19:42:45Z

@coleenp Pushed as commit 9f46fc2.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

8310906: Fix -Wconversion warnings in runtime, oops and some code hea…

9b7fdef

…der files.

openjdk bot changed the title ~~8310906: Fix -Wconversion warnings in runtime, oops and some code header files~~ 8310906: Fix -Wconversion warnings in runtime, oops and some code header files. Jun 27, 2023

openjdk bot added the rfr Pull request is ready for review label Jun 27, 2023

openjdk bot added serviceability serviceability-dev@openjdk.org hotspot hotspot-dev@openjdk.org labels Jun 27, 2023

stefank reviewed Jun 27, 2023

View reviewed changes

coleenp added 2 commits June 27, 2023 15:10

Make delta_as_int take pointers and fix cast. Missed one in stubCodeG…

99a15d6

…enerator.hpp

Fixed the comment.

858e9cf

Use pointer_delta_as_int for the name that uses pointer_delta, fix ne…

9fed8c8

…gative case to just do checked_cast.

iklam approved these changes Jun 28, 2023

View reviewed changes

openjdk bot added the ready Pull request is ready to be integrated label Jun 28, 2023

fparain approved these changes Jun 28, 2023

View reviewed changes

Clarify that pointer_delta_as_int() returns a non-negative int.

856cafd

openjdk bot added the integrated Pull request has been integrated label Jun 28, 2023

openjdk bot closed this Jun 28, 2023

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Jun 28, 2023

coleenp deleted the ptr-conversion branch June 28, 2023 19:47

zifeihan mentioned this pull request Jun 29, 2023

8311074: RISC-V: Fix -Wconversion warnings in some code header files #14702

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8310906: Fix -Wconversion warnings in runtime, oops and some code header files. #14675

8310906: Fix -Wconversion warnings in runtime, oops and some code header files. #14675

coleenp commented Jun 27, 2023 •

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8310906: Fix -Wconversion warnings in runtime, oops and some code header files. #14675

8310906: Fix -Wconversion warnings in runtime, oops and some code header files. #14675

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coleenp commented Jun 27, 2023 • edited by openjdk bot

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