[PATCH] D96881: Avoid Bitcast-GEP fusion for void pointers

[mohammad hadi jooybar via Phabricator via llvm-commits]

hjooybar2 added a comment.

@nikic By making a little modification in my changeset, now none of existing tests are failing. I added a new test to show how the code is supposed to look like.

Here is how newly added test would have looked like with the main branch:

  ; CHECK-NEXT:  entry:
  ; CHECK-NEXT:    [[CALL:%.*]] = call noalias dereferenceable_or_null(16) i8* @malloc(i64 16)
  ; CHECK-NEXT:    [[G3:%.*]] = getelementptr i8, i8* [[CALL]], i64 12
  ; CHECK-NEXT:    [[TMP0:%.*]] = bitcast i8* [[G3]] to i32*
  ; CHECK-NEXT:    [[A_C:%.*]] = load i32, i32* [[TMP0]], align 4
  ; CHECK-NEXT:    ret i32 [[A_C]]
  ;

My modification causes the `InstCombine` to behave differently between `Alloca` and `malloc` like functions. It actually makes sense, since `Alloca` usually has type but `malloc` is always `void*`

In conclusion, by latest update, all tests passed successfully and a new test is added to show how the optimization looks like.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D96881/new/

https://reviews.llvm.org/D96881