[PATCH] D127253: [AMDGPU] Use v_mad_u64_u32 for IMAD32

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec added inline comments.


================
Comment at: llvm/test/CodeGen/AMDGPU/mad_u64_u32.ll:46
+; GFX9-NEXT:    s_mov_b32 s0, 42
+; GFX9-NEXT:    v_mad_u64_u32 v[0:1], s[0:1], v0, v1, s[0:1]
+; GFX9-NEXT:    ; return to shader part epilog
----------------
rampitec wrote:
> foad wrote:
> > As a follow up it would be nice if we could fold the "42" into the mad as an inline src2.
> Sure. I will take a look why didn't it fold in a followup.
This actually did not fold because of the IMPLICIT_DEF. This is technically not a constant, but a 64 bit partial undef:
```
  %3:sreg_32 = S_MOV_B32 42
  %5:sreg_32 = IMPLICIT_DEF
  %4:sreg_64 = REG_SEQUENCE killed %3:sreg_32, %subreg.sub0, killed %5:sreg_32, %subreg.sub1
  %7:vreg_64, %8:sreg_64 = V_MAD_U64_U32_e64 %0:vgpr_32, %1:vgpr_32, killed %4:sreg_64, 0, implicit $exec
```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D127253/new/

https://reviews.llvm.org/D127253