[PATCH] D136267: [AMDGPU] Speedup GCNDownwardRPTracker::advanceBeforeNext

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

I'm now hitting an UNREACHABLE "register isn't live" in this somewhat reduced test case. Can you investigate/fix/revert as appropriate please? Thanks!

  ; RUN: llc -march=amdgcn -mcpu=gfx900 < %s
  
  declare void @llvm.amdgcn.kill(i1)
  declare <4 x float> @llvm.amdgcn.image.sample.2d.v4f32.f32(i32 immarg, float, float, <8 x i32>, <4 x i32>, i1 immarg, i32 immarg, i32 immarg)
  declare <2 x half> @llvm.amdgcn.cvt.pkrtz(float, float)
  declare void @llvm.amdgcn.exp.compr.v2f16(i32 immarg, i32 immarg, <2 x half>, <2 x half>, i1 immarg, i1 immarg)
  
  define amdgpu_ps void @_amdgpu_ps_main(float %arg) {
  bb:
    %i = fcmp olt float %arg, 0.000000e+00
    br i1 %i, label %bb5, label %bb1
  
  bb1:
    %i2 = call <4 x float> @llvm.amdgcn.image.sample.2d.v4f32.f32(i32 15, float 0.000000e+00, float %arg, <8 x i32> zeroinitializer, <4 x i32> zeroinitializer, i1 false, i32 0, i32 0)
    %i3 = extractelement <4 x float> %i2, i64 1
    %i4 = extractelement <4 x float> %i2, i64 0
    br label %bb6
  
  bb5:
    call void @llvm.amdgcn.kill(i1 false)
    br label %bb6
  
  bb6:
    %i7 = phi float [ 0.000000e+00, %bb5 ], [ %i3, %bb1 ]
    %i8 = phi float [ 0.000000e+00, %bb5 ], [ 1.000000e+00, %bb1 ]
    %i9 = phi float [ undef, %bb5 ], [ %i4, %bb1 ]
    %i10 = call <2 x half> @llvm.amdgcn.cvt.pkrtz(float 0.000000e+00, float %i7)
    %i11 = call <2 x half> @llvm.amdgcn.cvt.pkrtz(float %i8, float %i9)
    call void @llvm.amdgcn.exp.compr.v2f16(i32 0, i32 0, <2 x half> %i10, <2 x half> %i11, i1 false, i1 false)
    ret void
  }


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  https://reviews.llvm.org/D136267/new/

https://reviews.llvm.org/D136267