[PATCH] D148117: [AMDGPU] Don't S_MOV_B32 into $scc

[Diana Picus via Phabricator via llvm-commits]

rovka updated this revision to Diff 512810.
rovka added a comment.

Addressed the comment. Thanks for the quick review!


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148117/new/

https://reviews.llvm.org/D148117

Files:
  llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
  llvm/test/CodeGen/AMDGPU/fold_16bit_imm.mir
  llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir


Index: llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
===================================================================
--- llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
+++ llvm/test/CodeGen/AMDGPU/peephole-fold-imm.mir
@@ -1,6 +1,51 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 # RUN: llc -mtriple=amdgcn--amdhsa -mcpu=gfx908 -verify-machineinstrs -run-pass peephole-opt -o - %s | FileCheck -check-prefix=GCN %s
 
+---
+name:            fold_simm_virtual
+body:             |
+  bb.0:
+
+    ; GCN-LABEL: name: fold_simm_virtual
+    ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 0
+    ; GCN-NEXT: [[S_MOV_B32_1:%[0-9]+]]:sreg_32 = S_MOV_B32 0
+    ; GCN-NEXT: SI_RETURN_TO_EPILOG
+    %0:sreg_32 = S_MOV_B32 0
+    %1:sreg_32 = COPY killed %0
+    SI_RETURN_TO_EPILOG
+
+...
+
+---
+name:            fold_simm_physical
+body:             |
+  bb.0:
+
+    ; GCN-LABEL: name: fold_simm_physical
+    ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 0
+    ; GCN-NEXT: $sgpr1 = S_MOV_B32 0
+    ; GCN-NEXT: SI_RETURN_TO_EPILOG
+    %0:sreg_32 = S_MOV_B32 0
+    $sgpr1 = COPY killed %0
+    SI_RETURN_TO_EPILOG
+
+...
+
+---
+name:            dont_fold_simm_scc
+body:             |
+  bb.0:
+
+    ; GCN-LABEL: name: dont_fold_simm_scc
+    ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32 = S_MOV_B32 0
+    ; GCN-NEXT: $scc = COPY killed [[S_MOV_B32_]]
+    ; GCN-NEXT: SI_RETURN_TO_EPILOG
+    %0:sreg_32 = S_MOV_B32 0
+    $scc = COPY killed %0
+    SI_RETURN_TO_EPILOG
+
+...
+
 ---
 name:            fold_simm_16_sub_to_lo
 body:             |
Index: llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -3090,7 +3090,12 @@
       assert(UseMI.getOperand(1).getReg().isVirtual());
     }
 
-    UseMI.setDesc(get(NewOpc));
+    const MCInstrDesc &NewMCID = get(NewOpc);
+    if (DstReg.isPhysical() &&
+        !RI.getRegClass(NewMCID.operands()[0].RegClass)->contains(DstReg))
+      return false;
+
+    UseMI.setDesc(NewMCID);
     UseMI.getOperand(1).ChangeToImmediate(Imm.getSExtValue());
     UseMI.addImplicitDefUseOperands(*UseMI.getParent()->getParent());
     return true;


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