[llvm] [AMDGPU] Mark AGPR tuple implicit in the first instr of AGPR spills. (PR #115285)
via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 7 01:38:51 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu
Author: Pravin Jagtap (pravinjagtap)
<details>
<summary>Changes</summary>
When AGPRs are spilled to stack through VGPRs, the pei only marks the AGPR tuple as implicit-def. To preserve the liveness, it should also mark the tuple implicit.
---
Full diff: https://github.com/llvm/llvm-project/pull/115285.diff
2 Files Affected:
- (modified) llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp (+2)
- (modified) llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir (+5-5)
``````````diff
diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index 707468892d1779..dc7952ee67f033 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -1808,6 +1808,8 @@ void SIRegisterInfo::buildSpillLoadStore(
.addReg(SubReg, getKillRegState(IsKill));
if (NeedSuperRegDef)
AccRead.addReg(ValueReg, RegState::ImplicitDefine);
+ if (NeedSuperRegImpOperand && (IsFirstSubReg || IsLastSubReg))
+ AccRead.addReg(ValueReg, RegState::Implicit);
AccRead->setAsmPrinterFlag(MachineInstr::ReloadReuse);
}
SubReg = TmpIntermediateVGPR;
diff --git a/llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir b/llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir
index 460f6d24b9b18e..5bdb24db9accab 100644
--- a/llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir
+++ b/llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir
@@ -3,7 +3,6 @@
# RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 %s -o - -run-pass prologepilog,machine-cp -verify-machineinstrs | FileCheck -check-prefix=GFX908-PEI-MACHINECP %s
# When VGPRs are available for spilling, prologepilog marks the tuple implicit-def as well as implicit in the first spill instruction.
-# As a consequence, machine-cp would NOT delete agpr2 copy here.
---
name: agpr-spill-to-vgpr-machine-cp
@@ -43,8 +42,8 @@ body: |
S_ENDPGM 0
...
-# When VGPRs are NOT available for spilling (stack is used), prologepilog marks the tuple implicit-def only and NOT implicit.
-# As a consequence, machine-cp would delete agpr2 copy here. Presently, this is incorrect behavior.
+# When VGPRs are NOT available for spilling (stack is used), prologepilog should also mark the tuple implicit-def and implicit (similar to above usecase).
+# As a consequence, machine-cp would not delete agpr2 copy here.
---
name: agpr-spill-to-vgpr-to-stack-machine-cp
@@ -66,7 +65,7 @@ body: |
; GFX908-PEI-NEXT: renamable $agpr2 = COPY renamable $vgpr1, implicit $exec
; GFX908-PEI-NEXT: $vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9 = IMPLICIT_DEF
; GFX908-PEI-NEXT: $vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17 = IMPLICIT_DEF
- ; GFX908-PEI-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr0, implicit $exec, implicit-def $agpr0_agpr1_agpr2
+ ; GFX908-PEI-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr0, implicit $exec, implicit-def $agpr0_agpr1_agpr2, implicit $agpr0_agpr1_agpr2
; GFX908-PEI-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 0, 0, 0, implicit $exec, implicit $agpr0_agpr1_agpr2 :: (store (s32) into %stack.0, addrspace 5)
; GFX908-PEI-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr1, implicit $exec
; GFX908-PEI-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 4, 0, 0, implicit $exec :: (store (s32) into %stack.0 + 4, addrspace 5)
@@ -77,9 +76,10 @@ body: |
; GFX908-PEI-MACHINECP: liveins: $vgpr0, $vgpr1, $vgpr18, $vgpr19, $vgpr20, $vgpr21, $vgpr22, $vgpr23, $vgpr24, $vgpr25, $vgpr26, $vgpr27, $vgpr28, $vgpr29, $vgpr30, $vgpr31, $vgpr32, $vgpr33, $vgpr34, $vgpr35, $vgpr36, $vgpr37, $vgpr38, $vgpr39, $vgpr48, $vgpr49, $vgpr50, $vgpr51, $vgpr52, $vgpr53, $vgpr54, $vgpr55
; GFX908-PEI-MACHINECP-NEXT: {{ $}}
; GFX908-PEI-MACHINECP-NEXT: renamable $agpr0 = COPY renamable $vgpr0, implicit $exec
+ ; GFX908-PEI-MACHINECP-NEXT: renamable $agpr2 = COPY renamable $vgpr1, implicit $exec
; GFX908-PEI-MACHINECP-NEXT: $vgpr2_vgpr3_vgpr4_vgpr5_vgpr6_vgpr7_vgpr8_vgpr9 = IMPLICIT_DEF
; GFX908-PEI-MACHINECP-NEXT: $vgpr10_vgpr11_vgpr12_vgpr13_vgpr14_vgpr15_vgpr16_vgpr17 = IMPLICIT_DEF
- ; GFX908-PEI-MACHINECP-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr0, implicit $exec, implicit-def $agpr0_agpr1_agpr2
+ ; GFX908-PEI-MACHINECP-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr0, implicit $exec, implicit-def $agpr0_agpr1_agpr2, implicit $agpr0_agpr1_agpr2
; GFX908-PEI-MACHINECP-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 0, 0, 0, implicit $exec, implicit $agpr0_agpr1_agpr2 :: (store (s32) into %stack.0, addrspace 5)
; GFX908-PEI-MACHINECP-NEXT: $vgpr40 = V_ACCVGPR_READ_B32_e64 $agpr1, implicit $exec
; GFX908-PEI-MACHINECP-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, $sgpr32, 4, 0, 0, implicit $exec :: (store (s32) into %stack.0 + 4, addrspace 5)
``````````
</details>
https://github.com/llvm/llvm-project/pull/115285
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