[llvm] r287710 - Before sample pgo annotation, do not inline a function that has no debug info. (NFC)

[Dehao Chen via llvm-commits]

I thought NFC applies to "obvious change to fix corner-case bugs", and
apparently I was wrong and I'm sorry about that. What's the recommend steps
to move forward for situations like this? Shall I revert the patch and send
out a code review?

On Mon, Nov 28, 2016 at 10:04 AM, David Blaikie <dblaikie at gmail.com> wrote:

>
>
> On Tue, Nov 22, 2016 at 2:59 PM Dehao Chen via llvm-commits <
> llvm-commits at lists.llvm.org> wrote:
>
>> Author: dehao
>> Date: Tue Nov 22 16:50:01 2016
>> New Revision: 287710
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=287710&view=rev
>> Log:
>> Before sample pgo annotation, do not inline a function that has no debug
>> info. (NFC)
>>
>
> (+1 to Paul's comment - this sounds like a change, has test changes, and
> is probably not NFC)
>
> Also: This sounds like it does the opposite of what we want as a
> requirement: that the presence or absence of debug info should not change
> the resulting code.
>
> What's the deal?
>

This particular pass requires debug info to make decisions. This is
mandated by pass manager: even with -g0, PM will make sure debug info is
available before this pass. But if user manually removed the debug info,
the code should also handle it correctly, which is fixed by this patch.

Dehao


>
>
>>
>> If there is no debug info in the callee, inlining it will not help
>> annotator. This avoids infinite loop as reported in PR/31119.
>>
>> Added:
>>     llvm/trunk/test/Transforms/SampleProfile/Inputs/nodebug.prof
>>     llvm/trunk/test/Transforms/SampleProfile/nodebug.ll
>> Modified:
>>     llvm/trunk/lib/Transforms/IPO/SampleProfile.cpp
>>     llvm/trunk/test/Transforms/SampleProfile/early-inline.ll
>>
>> Modified: llvm/trunk/lib/Transforms/IPO/SampleProfile.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
>> Transforms/IPO/SampleProfile.cpp?rev=287710&r1=287709&r2=287710&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/lib/Transforms/IPO/SampleProfile.cpp (original)
>> +++ llvm/trunk/lib/Transforms/IPO/SampleProfile.cpp Tue Nov 22 16:50:01
>> 2016
>> @@ -651,6 +651,8 @@ bool SampleProfileLoader::inlineHotFunct
>>        InvokeInst *II = dyn_cast<InvokeInst>(I);
>>        Function *CalledFunction =
>>            (CI == nullptr ? II->getCalledFunction() :
>> CI->getCalledFunction());
>> +      if (!CalledFunction || !CalledFunction->getSubprogram())
>> +        continue;
>>        DebugLoc DLoc = I->getDebugLoc();
>>        uint64_t NumSamples = findCalleeFunctionSamples(*I)-
>> >getTotalSamples();
>>        if ((CI && InlineFunction(CI, IFI)) || (II && InlineFunction(II,
>> IFI))) {
>>
>> Added: llvm/trunk/test/Transforms/SampleProfile/Inputs/nodebug.prof
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
>> Transforms/SampleProfile/Inputs/nodebug.prof?rev=287710&view=auto
>> ============================================================
>> ==================
>> --- llvm/trunk/test/Transforms/SampleProfile/Inputs/nodebug.prof (added)
>> +++ llvm/trunk/test/Transforms/SampleProfile/Inputs/nodebug.prof Tue Nov
>> 22 16:50:01 2016
>> @@ -0,0 +1,2 @@
>> +foo:100:10
>> + 0: bar:10
>>
>> Modified: llvm/trunk/test/Transforms/SampleProfile/early-inline.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
>> Transforms/SampleProfile/early-inline.ll?rev=287710&r1=
>> 287709&r2=287710&view=diff
>> ============================================================
>> ==================
>> --- llvm/trunk/test/Transforms/SampleProfile/early-inline.ll (original)
>> +++ llvm/trunk/test/Transforms/SampleProfile/early-inline.ll Tue Nov 22
>> 16:50:01 2016
>> @@ -28,7 +28,7 @@ define void @_Z3foov() #0 personality i8
>>  }
>>
>>  ; Function Attrs: nounwind uwtable
>> -define internal void @_ZL3barv() #1 {
>> +define internal void @_ZL3barv() !dbg !12 {
>>    ret void
>>  }
>>
>> @@ -45,3 +45,4 @@ declare i32 @__gxx_personality_v0(...)
>>  !9 = !DILocation(line: 6, column: 3, scope: !6)
>>  !10 = !DILocation(line: 8, column: 5, scope: !11)
>>  !11 = distinct !DILexicalBlock(scope: !6, file: !1, line: 7, column: 7)
>> +!12 = distinct !DISubprogram(linkageName: "_ZL3barv", scope: !1, line:
>> 20, scopeLine: 20, unit: !0)
>>
>> Added: llvm/trunk/test/Transforms/SampleProfile/nodebug.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
>> Transforms/SampleProfile/nodebug.ll?rev=287710&view=auto
>> ============================================================
>> ==================
>> --- llvm/trunk/test/Transforms/SampleProfile/nodebug.ll (added)
>> +++ llvm/trunk/test/Transforms/SampleProfile/nodebug.ll Tue Nov 22
>> 16:50:01 2016
>> @@ -0,0 +1,20 @@
>> +; RUN: opt < %s -sample-profile -sample-profile-file=%S/
>> Inputs/nodebug.prof
>> +
>> +define void @foo() !dbg !3 {
>> +  call void @bar(), !dbg !4
>> +  ret void
>> +}
>> +
>> +define void @bar() {
>> +  call void @bar()
>> +  ret void
>> +}
>> +
>> +!llvm.dbg.cu = !{!0}
>> +!llvm.module.flags = !{!2}
>> +
>> +!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1)
>> +!1 = !DIFile(filename: "t", directory: "/tmp/")
>> +!2 = !{i32 2, !"Debug Info Version", i32 3}
>> +!3 = distinct !DISubprogram(name: "a", scope: !1, file: !1, line: 10,
>> unit: !0)
>> +!4 = !DILocation(line: 10, scope: !3)
>>
>>
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>
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