[llvm] fb81271 - [AMDGPU] Fix lowering of AMDGPU::G_CTTZ_ZERO_UNDEF to AMDGPU::G_AMDGPU_FFBL_B32

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2021-08-17T18:09:57+01:00
New Revision: fb81271e8b44cafff3abf4c05d1485d4b4832e6e

URL: https://github.com/llvm/llvm-project/commit/fb81271e8b44cafff3abf4c05d1485d4b4832e6e
DIFF: https://github.com/llvm/llvm-project/commit/fb81271e8b44cafff3abf4c05d1485d4b4832e6e.diff

LOG: [AMDGPU] Fix lowering of AMDGPU::G_CTTZ_ZERO_UNDEF to AMDGPU::G_AMDGPU_FFBL_B32

As mentioned on D107474, there was a copy+paste typo repeating G_CTLZ_ZERO_UNDEF that coverity reported as dead code.

Differential Revision: https://reviews.llvm.org/D108210

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp
    llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp b/llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp
index 24e2e720153a..9c00ed76985f 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPURegisterBankInfo.cpp
@@ -2539,7 +2539,7 @@ void AMDGPURegisterBankInfo::applyMappingImpl(
     SmallVector<Register, 2> SrcRegs(OpdMapper.getVRegs(1));
     unsigned NewOpc = Opc == AMDGPU::G_CTLZ_ZERO_UNDEF
                           ? AMDGPU::G_AMDGPU_FFBH_U32
-                          : Opc == AMDGPU::G_CTLZ_ZERO_UNDEF
+                          : Opc == AMDGPU::G_CTTZ_ZERO_UNDEF
                                 ? AMDGPU::G_AMDGPU_FFBL_B32
                                 : Opc;
     unsigned Idx = NewOpc == AMDGPU::G_AMDGPU_FFBH_U32;

diff  --git a/llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir b/llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir
index adbe22aac9f4..3eb1ae47b4db 100644
--- a/llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir
+++ b/llvm/test/CodeGen/AMDGPU/GlobalISel/regbankselect-cttz-zero-undef.mir
@@ -60,11 +60,11 @@ body: |
     ; CHECK-LABEL: name: cttz_zero_undef_s64_v
     ; CHECK: [[COPY:%[0-9]+]]:vgpr(s64) = COPY $vgpr0_vgpr1
     ; CHECK: [[UV:%[0-9]+]]:vgpr(s32), [[UV1:%[0-9]+]]:vgpr(s32) = G_UNMERGE_VALUES [[COPY]](s64)
-    ; CHECK: [[CTTZ_ZERO_UNDEF:%[0-9]+]]:vgpr(s32) = G_CTTZ_ZERO_UNDEF [[UV]](s32)
-    ; CHECK: [[CTTZ_ZERO_UNDEF1:%[0-9]+]]:vgpr(s32) = G_CTTZ_ZERO_UNDEF [[UV1]](s32)
+    ; CHECK: [[AMDGPU_FFBL_B32_:%[0-9]+]]:vgpr(s32) = G_AMDGPU_FFBL_B32 [[UV]](s32)
+    ; CHECK: [[AMDGPU_FFBL_B32_1:%[0-9]+]]:vgpr(s32) = G_AMDGPU_FFBL_B32 [[UV1]](s32)
     ; CHECK: [[C:%[0-9]+]]:vgpr(s32) = G_CONSTANT i32 32
-    ; CHECK: [[ADD:%[0-9]+]]:vgpr(s32) = G_ADD [[CTTZ_ZERO_UNDEF1]], [[C]]
-    ; CHECK: [[UMIN:%[0-9]+]]:vgpr(s32) = G_UMIN [[CTTZ_ZERO_UNDEF]], [[ADD]]
+    ; CHECK: [[ADD:%[0-9]+]]:vgpr(s32) = G_ADD [[AMDGPU_FFBL_B32_1]], [[C]]
+    ; CHECK: [[UMIN:%[0-9]+]]:vgpr(s32) = G_UMIN [[AMDGPU_FFBL_B32_]], [[ADD]]
     ; CHECK: S_ENDPGM 0, implicit [[UMIN]](s32)
     %0:_(s64) = COPY $vgpr0_vgpr1
     %1:_(s32) = G_CTTZ_ZERO_UNDEF %0