Address reviewer comments

Author: dc03-work

llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h

@@ -866,7 +866,8 @@ class CombinerHelper {
   /// Combine insert vector element OOB.
   bool matchInsertVectorElementOOB(MachineInstr &MI, BuildFnTy &MatchInfo);
 
-  bool matchFreezeOfSingleMaybePoisonOperand(MachineInstr &MI, BuildFnTy &MatchInfo);
+  bool matchFreezeOfSingleMaybePoisonOperand(MachineInstr &MI,
+                                             BuildFnTy &MatchInfo);
 
 private:
   /// Checks for legality of an indexed variant of \p LdSt.

llvm/include/llvm/Target/GlobalISel/Combine.td

@@ -224,8 +224,8 @@ def idempotent_prop : GICombineRule<
 // when Op0 is not guaranteed non-poison
 def push_freeze_to_prevent_poison_propagation : GICombineRule<
   (defs root:$root, build_fn_matchinfo:$matchinfo),
-  (match (wip_match_opcode G_FREEZE):$root,
-         [{ return Helper.matchFreezeOfSingleMaybePoisonOperand(*${root}, ${matchinfo}); }]),
+  (match (G_FREEZE $dst, $src):$root,
+         [{ return !isGuaranteedNotToBePoison(${src}.getReg(), MRI) && Helper.matchFreezeOfSingleMaybePoisonOperand(*${root}, ${matchinfo}); }]),
   (apply [{ Helper.applyBuildFn(*${root}, ${matchinfo}); }])>;
 
 def extending_loads : GICombineRule<

llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -242,10 +242,10 @@ bool CombinerHelper::matchFreezeOfSingleMaybePoisonOperand(
   if (canCreateUndefOrPoison(OrigOp, MRI))
     return false;
 
-  std::optional<MachineOperand> MaybePoisonOperand = std::nullopt;
+  std::optional<MachineOperand> MaybePoisonOperand;
   for (MachineOperand &Operand : OrigDef->uses()) {
-    // Avoid working on non-register operands or physical registers.
-    if (!Operand.isReg() || Operand.getReg().isPhysical())
+    // Avoid working on non-register operands.
+    if (!Operand.isReg())
       return false;
 
     if (isGuaranteedNotToBeUndefOrPoison(Operand.getReg(), MRI))
@@ -258,15 +258,12 @@ bool CombinerHelper::matchFreezeOfSingleMaybePoisonOperand(
       return false;
   }
 
-  // Eliminate freeze if all operands are guaranteed non-poison
+  // Eliminate freeze if all operands are guaranteed non-poison.
   if (!MaybePoisonOperand) {
     MatchInfo = [=](MachineIRBuilder &B) { MRI.replaceRegWith(DstOp, OrigOp); };
     return true;
   }
 
-  if (!MaybePoisonOperand->isReg())
-    return false;
-
   Register MaybePoisonOperandReg = MaybePoisonOperand->getReg();
   LLT MaybePoisonOperandRegTy = MRI.getType(MaybePoisonOperandReg);
 
@@ -3118,7 +3115,6 @@ bool CombinerHelper::matchHoistLogicOpWithSameOpcodeHands(
   MachineInstr *RightHandInst = getDefIgnoringCopies(RHSReg, MRI);
   if (!LeftHandInst || !RightHandInst)
     return false;
-
   unsigned HandOpcode = LeftHandInst->getOpcode();
   if (HandOpcode != RightHandInst->getOpcode())
     return false;