[clang] Change some placeholders from undef to poison [NFC]

Author: nunoplopes

clang/lib/CodeGen/CGExprComplex.cpp

@@ -471,7 +471,7 @@ ComplexPairTy ComplexExprEmitter::VisitExpr(Expr *E) {
   CGF.ErrorUnsupported(E, "complex expression");
   llvm::Type *EltTy =
     CGF.ConvertType(getComplexType(E->getType())->getElementType());
-  llvm::Value *U = llvm::UndefValue::get(EltTy);
+  llvm::Value *U = llvm::PoisonValue::get(EltTy);
   return ComplexPairTy(U, U);
 }
 
@@ -1449,7 +1449,7 @@ ComplexPairTy ComplexExprEmitter::VisitVAArgExpr(VAArgExpr *E) {
     CGF.ErrorUnsupported(E, "complex va_arg expression");
     llvm::Type *EltTy =
       CGF.ConvertType(E->getType()->castAs<ComplexType>()->getElementType());
-    llvm::Value *U = llvm::UndefValue::get(EltTy);
+    llvm::Value *U = llvm::PoisonValue::get(EltTy);
     return ComplexPairTy(U, U);
   }
 

clang/lib/CodeGen/CGExprScalar.cpp

@@ -1828,7 +1828,7 @@ Value *ScalarExprEmitter::VisitExpr(Expr *E) {
   CGF.ErrorUnsupported(E, "scalar expression");
   if (E->getType()->isVoidType())
     return nullptr;
-  return llvm::UndefValue::get(CGF.ConvertType(E->getType()));
+  return llvm::PoisonValue::get(CGF.ConvertType(E->getType()));
 }
 
 Value *

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -486,7 +486,7 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   if (IndirectBranch) {
     llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
     if (PN->getNumIncomingValues() == 0) {
-      PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
+      PN->replaceAllUsesWith(llvm::PoisonValue::get(PN->getType()));
       PN->eraseFromParent();
     }
   }
@@ -1106,8 +1106,8 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
   // Create a marker to make it easy to insert allocas into the entryblock
   // later.  Don't create this with the builder, because we don't want it
   // folded.
-  llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
-  AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "allocapt", EntryBB);
+  llvm::Value *Poison = llvm::PoisonValue::get(Int32Ty);
+  AllocaInsertPt = new llvm::BitCastInst(Poison, Int32Ty, "allocapt", EntryBB);
 
   ReturnBlock = getJumpDestInCurrentScope("return");
 

clang/lib/CodeGen/CodeGenModule.cpp

@@ -733,7 +733,7 @@ void CodeGenModule::checkAliases() {
   for (const GlobalDecl &GD : Aliases) {
     StringRef MangledName = getMangledName(GD);
     llvm::GlobalValue *Alias = GetGlobalValue(MangledName);
-    Alias->replaceAllUsesWith(llvm::UndefValue::get(Alias->getType()));
+    Alias->replaceAllUsesWith(llvm::PoisonValue::get(Alias->getType()));
     Alias->eraseFromParent();
   }
 }
@@ -5572,7 +5572,7 @@ void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D,
         }
       } else {
         ErrorUnsupported(D, "static initializer");
-        Init = llvm::UndefValue::get(getTypes().ConvertType(T));
+        Init = llvm::PoisonValue::get(getTypes().ConvertType(T));
       }
     } else {
       Init = Initializer;