[PATCH] D83101: [Scalarizer] ExtractElement handling w/ constant extract index

[mattias.v.eriksson@ericsson.com via Phabricator via llvm-commits]

materi added a comment.

In D83101#2223698 <https://reviews.llvm.org/D83101#2223698>, @lebedev.ri wrote:

> In D83101#2223689 <https://reviews.llvm.org/D83101#2223689>, @materi wrote:
>
>> We have seen some issues with missing symbols during linking that I think are caused by this patch. The origin of this is downstream fuzz testing.
>>
>> The global variable `aglobal` is renamed:
>>
>>   $ cat global.ll
>>   @aglobal = dso_local global i16 0, align 1
>>   @b = dso_local local_unnamed_addr global i16 0, align 1
>>   
>>   define dso_local void @c() local_unnamed_addr {
>>   entry:
>>     %d.sroa.0.1.vec.extract = extractelement <4 x i16*> <i16* @aglobal, i16* @aglobal, i16* @aglobal, i16* @aglobal>, i32 1
>>     %0 = ptrtoint i16* %d.sroa.0.1.vec.extract to i16
>>     store i16 %0, i16* @b, align 1
>>     ret void
>>   }
>>   
>>   $ opt -scalarizer global.ll -S
>>   ; ModuleID = 'global.ll'
>>   source_filename = "global.ll"
>>   
>>   @d.sroa.0.1.vec.extract = dso_local global i16 0, align 1
>>   @b = dso_local local_unnamed_addr global i16 0, align 1
>>   
>>   define dso_local void @c() local_unnamed_addr {
>>   entry:
>>     %0 = ptrtoint i16* @d.sroa.0.1.vec.extract to i16
>>     store i16 %0, i16* @b, align 1
>>     ret void
>>   }
>
> I see that the global is renamed, https://godbolt.org/z/PM95se, it's not really intentional.
> But i think something else is missing in this test - what's the failure? `-verify` passes

I don't think there is a verifier that points out this issue. But consider if there is another .ll file which has an external reference to the global:

  @aglobal = external dso_local local_unnamed_addr global i16, align 1
  define dso_local i16 @main() local_unnamed_addr #0 {
  entry:
    %0 = load i16, i16* @aglobal, align 1
    ret i16 %0
  }

In this case you get link error when `@aglobal` has been renamed in global.ll.


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  https://reviews.llvm.org/D83101/new/

https://reviews.llvm.org/D83101