r195495 - Debug Info: add a "Debug Info Version" module flag to output the current debug

[David Blaikie]

On Fri, Nov 22, 2013 at 12:07 PM, Manman Ren <manman.ren at gmail.com> wrote:

>
>
>
> On Fri, Nov 22, 2013 at 11:59 AM, Eric Christopher <echristo at gmail.com>wrote:
>
>> On Fri, Nov 22, 2013 at 11:42 AM, Manman Ren <manman.ren at gmail.com>
>> wrote:
>> > Author: mren
>> > Date: Fri Nov 22 13:42:45 2013
>> > New Revision: 195495
>> >
>> > URL: http://llvm.org/viewvc/llvm-project?rev=195495&view=rev
>> > Log:
>> > Debug Info: add a "Debug Info Version" module flag to output the
>> current debug
>> > info version number.
>> >
>> > Will error out when modules have different version numbers.
>> >
>>
>> I don't think the commit message or comment are correct. We're going
>> to strip debug info at module merge time if they have different
>> versions, not error out at merge time.
>>
>
> The commit message and the comment is for what is implemented in the
> patch. The module flag will be used to strip debug info later on.
> And I plan to talk about stripping debug info when the patch that actually
> strips debug info is committed.
> The comment tries to explain why we choose the error mode and what will
> happen if the linker sees different versions.
>
> Should we talk about how the module flag will be used when adding the
> module flag in the source code?
> Maybe if we want to be verbose.
>

It's not uncommon to do that - providing a comment about where this work
fits in the grand scheme of things either in the source or the commit
message, or both.

- David


>
> Manman
>
>
>>
>> -eric
>>
>> > Added:
>> >     cfe/trunk/test/CodeGen/debug-info-version.c
>> > Modified:
>> >     cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> >
>> > Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=195495&r1=195494&r2=195495&view=diff
>> >
>> ==============================================================================
>> > --- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original)
>> > +++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Fri Nov 22 13:42:45 2013
>> > @@ -258,6 +258,11 @@ void CodeGenModule::Release() {
>> >      // We can change from Warning to Latest if such mode is supported.
>> >      getModule().addModuleFlag(llvm::Module::Warning, "Dwarf Version",
>> >                                CodeGenOpts.DwarfVersion);
>> > +  if (DebugInfo)
>> > +    // We support a single version in the linked module: error out when
>> > +    // modules do not have the same version.
>> > +    getModule().addModuleFlag(llvm::Module::Error, "Debug Info
>> Version",
>> > +                              llvm::dwarf::DEBUG_INFO_VERSION);
>> >
>> >    SimplifyPersonality();
>> >
>> >
>> > Added: cfe/trunk/test/CodeGen/debug-info-version.c
>> > URL:
>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/debug-info-version.c?rev=195495&view=auto
>> >
>> ==============================================================================
>> > --- cfe/trunk/test/CodeGen/debug-info-version.c (added)
>> > +++ cfe/trunk/test/CodeGen/debug-info-version.c Fri Nov 22 13:42:45 2013
>> > @@ -0,0 +1,8 @@
>> > +// RUN: %clang -g -S -emit-llvm -o - %s | FileCheck %s
>> > +// RUN: %clang -S -emit-llvm -o - %s | FileCheck %s
>> --check-prefix=NO_DEBUG
>> > +int main (void) {
>> > +  return 0;
>> > +}
>> > +
>> > +// CHECK: metadata !{i32 1, metadata !"Debug Info Version", i32 1}
>> > +// NO_DEBUG-NOT: metadata !"Debug Info Version"
>> >
>> >
>> > _______________________________________________
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>> > cfe-commits at cs.uiuc.edu
>> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>
>
>
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