[llvm] bdaa82a - [AMDGPU] Mark AGPR tuple implicit in the first instr of AGPR spills. (#115285)

[via llvm-commits]

Author: Pravin Jagtap
Date: 2024-12-12T19:47:17+05:30
New Revision: bdaa82a7bb14b1016dbee554ef919323a197754d

URL: https://github.com/llvm/llvm-project/commit/bdaa82a7bb14b1016dbee554ef919323a197754d
DIFF: https://github.com/llvm/llvm-project/commit/bdaa82a7bb14b1016dbee554ef919323a197754d.diff

LOG: [AMDGPU] Mark AGPR tuple implicit in the first instr of AGPR spills. (#115285)

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.

Fixes: SWDEV-462189

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
    llvm/test/CodeGen/AMDGPU/av-spill-expansion-with-machine-cp.mir

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index 296c32fa4e0d09..2f5a99e5de5e3e 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -1817,6 +1817,8 @@ 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..dfe4b8a33f3967 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
@@ -11,6 +10,7 @@ tracksRegLiveness: true
 stack:
   - { id: 0, name: '', type: spill-slot, offset: 0, size: 128, alignment: 4 }
 machineFunctionInfo:
+  isEntryFunction: true
   scratchRSrcReg:  $sgpr0_sgpr1_sgpr2_sgpr3
   stackPtrOffsetReg: '$sgpr32'
   hasSpilledVGPRs: true
@@ -43,8 +43,8 @@ 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
@@ -52,6 +52,7 @@ tracksRegLiveness: true
 stack:
   - { id: 0, name: '', type: spill-slot, offset: 0, size: 128, alignment: 4 }
 machineFunctionInfo:
+  isEntryFunction: true
   scratchRSrcReg:  $sgpr0_sgpr1_sgpr2_sgpr3
   stackPtrOffsetReg: '$sgpr32'
   hasSpilledVGPRs: true
@@ -60,29 +61,34 @@ body: |
     successors:
     liveins: $vgpr0, $vgpr1
     ; GFX908-PEI-LABEL: name: agpr-spill-to-vgpr-to-stack-machine-cp
-    ; GFX908-PEI: 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: 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, $sgpr0_sgpr1_sgpr2_sgpr3
     ; GFX908-PEI-NEXT: {{  $}}
+    ; GFX908-PEI-NEXT: $sgpr0 = S_ADD_U32 $sgpr0, $noreg, implicit-def $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; GFX908-PEI-NEXT: $sgpr1 = S_ADDC_U32 $sgpr1, 0, implicit-def dead $scc, implicit $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
     ; GFX908-PEI-NEXT: renamable $agpr0 = COPY renamable $vgpr0, implicit $exec
     ; 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: 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 $agpr0, implicit $exec, implicit-def $agpr0_agpr1_agpr2, implicit $agpr0_agpr1_agpr2
+    ; GFX908-PEI-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, 0, 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)
+    ; GFX908-PEI-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, 0, 4, 0, 0, implicit $exec :: (store (s32) into %stack.0 + 4, addrspace 5)
     ; GFX908-PEI-NEXT: $vgpr55 = V_ACCVGPR_READ_B32_e64 $agpr2, implicit $exec, implicit $agpr0_agpr1_agpr2
     ; GFX908-PEI-NEXT: S_ENDPGM 0
     ;
     ; GFX908-PEI-MACHINECP-LABEL: name: agpr-spill-to-vgpr-to-stack-machine-cp
-    ; 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: 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, $sgpr0_sgpr1_sgpr2_sgpr3
     ; GFX908-PEI-MACHINECP-NEXT: {{  $}}
+    ; GFX908-PEI-MACHINECP-NEXT: $sgpr0 = S_ADD_U32 $sgpr0, $noreg, implicit-def $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
+    ; GFX908-PEI-MACHINECP-NEXT: $sgpr1 = S_ADDC_U32 $sgpr1, 0, implicit-def dead $scc, implicit $scc, implicit-def $sgpr0_sgpr1_sgpr2_sgpr3
     ; 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: 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 $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, 0, 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)
+    ; GFX908-PEI-MACHINECP-NEXT: BUFFER_STORE_DWORD_OFFSET $vgpr40, $sgpr0_sgpr1_sgpr2_sgpr3, 0, 4, 0, 0, implicit $exec :: (store (s32) into %stack.0 + 4, addrspace 5)
     ; GFX908-PEI-MACHINECP-NEXT: $vgpr55 = V_ACCVGPR_READ_B32_e64 $agpr2, implicit $exec, implicit $agpr0_agpr1_agpr2
     ; GFX908-PEI-MACHINECP-NEXT: S_ENDPGM 0
     renamable $agpr0 = COPY renamable $vgpr0, implicit $exec