AMDGPU: Handle brev and not cases in getConstValDefinedInReg #127483
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This was referenced Feb 17, 2025
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@llvm/pr-subscribers-backend-amdgpu Author: Matt Arsenault (arsenm) ChangesWe should not encounter these cases in the peephole-opt use today, Full diff: https://github.com/llvm/llvm-project/pull/127483.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index 07f1dc299c0e5..4cb07b1df04ce 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -1330,8 +1330,6 @@ Register SIInstrInfo::insertNE(MachineBasicBlock *MBB,
bool SIInstrInfo::getConstValDefinedInReg(const MachineInstr &MI,
const Register Reg,
int64_t &ImmVal) const {
- // TODO: Handle all the special cases handled in SIShrinkInstructions
- // (e.g. s_brev_b32 imm -> reverse(imm))
switch (MI.getOpcode()) {
case AMDGPU::V_MOV_B32_e32:
case AMDGPU::S_MOV_B32:
@@ -1349,6 +1347,28 @@ bool SIInstrInfo::getConstValDefinedInReg(const MachineInstr &MI,
return false;
}
+ case AMDGPU::S_BREV_B32:
+ case AMDGPU::V_BFREV_B32_e32:
+ case AMDGPU::V_BFREV_B32_e64: {
+ const MachineOperand &Src0 = MI.getOperand(1);
+ if (Src0.isImm()) {
+ ImmVal = static_cast<int64_t>(reverseBits<int32_t>(Src0.getImm()));
+ return MI.getOperand(0).getReg() == Reg;
+ }
+
+ return false;
+ }
+ case AMDGPU::S_NOT_B32:
+ case AMDGPU::V_NOT_B32_e32:
+ case AMDGPU::V_NOT_B32_e64: {
+ const MachineOperand &Src0 = MI.getOperand(1);
+ if (Src0.isImm()) {
+ ImmVal = static_cast<int64_t>(~static_cast<int32_t>(Src0.getImm()));
+ return MI.getOperand(0).getReg() == Reg;
+ }
+
+ return false;
+ }
default:
return false;
}
diff --git a/llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir b/llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
index 227af34f3fa6f..ddeb45a48a6ee 100644
--- a/llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
+++ b/llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
@@ -451,7 +451,7 @@ body: |
; GCN-LABEL: name: fold_s_brev_b32_simm_virtual_0
; GCN: [[S_BREV_B32_:%[0-9]+]]:sreg_32 = S_BREV_B32 1
- ; GCN-NEXT: [[COPY:%[0-9]+]]:sreg_32 = COPY killed [[S_BREV_B32_]]
+ ; GCN-NEXT: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 -2147483648
; GCN-NEXT: SI_RETURN_TO_EPILOG
%0:sreg_32 = S_BREV_B32 1
%1:sreg_32 = COPY killed %0
@@ -466,7 +466,7 @@ body: |
; GCN-LABEL: name: fold_s_brev_b32_simm_virtual_1
; GCN: [[S_BREV_B32_:%[0-9]+]]:sreg_32 = S_BREV_B32 -64
- ; GCN-NEXT: [[COPY:%[0-9]+]]:sreg_32 = COPY killed [[S_BREV_B32_]]
+ ; GCN-NEXT: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 67108863
; GCN-NEXT: SI_RETURN_TO_EPILOG
%0:sreg_32 = S_BREV_B32 -64
%1:sreg_32 = COPY killed %0
@@ -481,8 +481,8 @@ body: |
; GCN-LABEL: name: fold_v_bfrev_b32_e32_imm
; GCN: [[V_BFREV_B32_e32_:%[0-9]+]]:vgpr_32 = V_BFREV_B32_e32 1, implicit $exec
- ; GCN-NEXT: [[COPY:%[0-9]+]]:vgpr_32 = COPY killed [[V_BFREV_B32_e32_]]
- ; GCN-NEXT: SI_RETURN_TO_EPILOG [[COPY]]
+ ; GCN-NEXT: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 -2147483648, implicit $exec
+ ; GCN-NEXT: SI_RETURN_TO_EPILOG [[V_MOV_B32_e32_]]
%0:vgpr_32 = V_BFREV_B32_e32 1, implicit $exec
%1:vgpr_32 = COPY killed %0
SI_RETURN_TO_EPILOG %1
@@ -496,8 +496,8 @@ body: |
; GCN-LABEL: name: fold_v_bfrev_b32_e64_imm
; GCN: [[V_BFREV_B32_e64_:%[0-9]+]]:vgpr_32 = V_BFREV_B32_e64 1, implicit $exec
- ; GCN-NEXT: [[COPY:%[0-9]+]]:vgpr_32 = COPY killed [[V_BFREV_B32_e64_]]
- ; GCN-NEXT: SI_RETURN_TO_EPILOG [[COPY]]
+ ; GCN-NEXT: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 -2147483648, implicit $exec
+ ; GCN-NEXT: SI_RETURN_TO_EPILOG [[V_MOV_B32_e32_]]
%0:vgpr_32 = V_BFREV_B32_e64 1, implicit $exec
%1:vgpr_32 = COPY killed %0
SI_RETURN_TO_EPILOG %1
@@ -511,7 +511,7 @@ body: |
; GCN-LABEL: name: fold_s_not_b32_simm_virtual_0
; GCN: [[S_NOT_B32_:%[0-9]+]]:sreg_32 = S_NOT_B32 1, implicit-def $scc
- ; GCN-NEXT: [[COPY:%[0-9]+]]:sreg_32 = COPY killed [[S_NOT_B32_]]
+ ; GCN-NEXT: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 -2
; GCN-NEXT: SI_RETURN_TO_EPILOG
%0:sreg_32 = S_NOT_B32 1, implicit-def $scc
%1:sreg_32 = COPY killed %0
@@ -526,7 +526,7 @@ body: |
; GCN-LABEL: name: fold_s_not_b32_simm_virtual_1
; GCN: [[S_NOT_B32_:%[0-9]+]]:sreg_32 = S_NOT_B32 -64, implicit-def $scc
- ; GCN-NEXT: [[COPY:%[0-9]+]]:sreg_32 = COPY killed [[S_NOT_B32_]]
+ ; GCN-NEXT: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 63
; GCN-NEXT: SI_RETURN_TO_EPILOG
%0:sreg_32 = S_NOT_B32 -64, implicit-def $scc
%1:sreg_32 = COPY killed %0
@@ -541,8 +541,8 @@ body: |
; GCN-LABEL: name: fold_v_not_b32_e32_imm
; GCN: [[V_NOT_B32_e32_:%[0-9]+]]:vgpr_32 = V_NOT_B32_e32 1, implicit $exec
- ; GCN-NEXT: [[COPY:%[0-9]+]]:vgpr_32 = COPY killed [[V_NOT_B32_e32_]]
- ; GCN-NEXT: SI_RETURN_TO_EPILOG [[COPY]]
+ ; GCN-NEXT: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 -2, implicit $exec
+ ; GCN-NEXT: SI_RETURN_TO_EPILOG [[V_MOV_B32_e32_]]
%0:vgpr_32 = V_NOT_B32_e32 1, implicit $exec
%1:vgpr_32 = COPY killed %0
SI_RETURN_TO_EPILOG %1
@@ -556,8 +556,8 @@ body: |
; GCN-LABEL: name: fold_v_not_b32_e64_imm
; GCN: [[V_NOT_B32_e64_:%[0-9]+]]:vgpr_32 = V_NOT_B32_e64 1, implicit $exec
- ; GCN-NEXT: [[COPY:%[0-9]+]]:vgpr_32 = COPY killed [[V_NOT_B32_e64_]]
- ; GCN-NEXT: SI_RETURN_TO_EPILOG [[COPY]]
+ ; GCN-NEXT: [[V_MOV_B32_e32_:%[0-9]+]]:vgpr_32 = V_MOV_B32_e32 -2, implicit $exec
+ ; GCN-NEXT: SI_RETURN_TO_EPILOG [[V_MOV_B32_e32_]]
%0:vgpr_32 = V_NOT_B32_e64 1, implicit $exec
%1:vgpr_32 = COPY killed %0
SI_RETURN_TO_EPILOG %1
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February 18, 2025 04:21
We should not encounter these cases in the peephole-opt use today, but get the common helper function to handle these.
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We should not encounter these cases in the peephole-opt use today,
but get the common helper function to handle these.