[PATCH] D103323: [DAGCombiner] Add support for mulhi const folding in DAGCombiner

Mon Jul 5 01:50:24 PDT 2021

dstuttard added inline comments.

================
Comment at: llvm/test/CodeGen/AMDGPU/dagcombine-mulhs-const.ll:5
+; MULHS C1, C2 replacement results in 0x4237 in the following add
+; GCN: s_add_u32 s0, 0x4237, s0
+
----------------
foad wrote:
> Obviously folding the mul_hi is good, but the s_add that you check for looks like this:
> ```
>         s_mov_b32 s0, 0x346d900
>         ...
>         s_add_u32 s0, 0x4237, s0
> ```
> so it should also be folded to a constant!
Yes - that could be another one to do - then fix up this test (or not worry about it at all given that there's now an X86 test that tests this, thanks to Simon)

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103323/new/

https://reviews.llvm.org/D103323