Implement support for -fwrapv, rdar://7221421

As part of this, pull together trapv handling into the same enum.

This also add support for NSW multiplies.

This also makes PCH disagreement on overflow behavior silent, since it
really doesn't matter except for warnings and codegen (no macros get 
defined etc).

llvm-svn: 106956

1 files changed, 44 insertions, 22 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 4372279175e..72da22695f8 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -291,9 +291,17 @@ public:
 
   // Binary Operators.
   Value *EmitMul(const BinOpInfo &Ops) {
-    if (CGF.getContext().getLangOptions().OverflowChecking
-        && Ops.Ty->isSignedIntegerType())
-      return EmitOverflowCheckedBinOp(Ops);
+    if (Ops.Ty->isSignedIntegerType()) {
+      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
+      case LangOptions::SOB_Undefined:
+        return Builder.CreateNSWMul(Ops.LHS, Ops.RHS, "mul");
+      case LangOptions::SOB_Defined:
+        return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
+      case LangOptions::SOB_Trapping:
+        return EmitOverflowCheckedBinOp(Ops);
+      }
+    }
+    
     if (Ops.LHS->getType()->isFPOrFPVectorTy())
       return Builder.CreateFMul(Ops.LHS, Ops.RHS, "mul");
     return Builder.CreateMul(Ops.LHS, Ops.RHS, "mul");
@@ -1119,9 +1127,17 @@ Value *ScalarExprEmitter::VisitUnaryMinus(const UnaryOperator *E) {
     return Builder.CreateFNeg(Op, "neg");
   
   // Signed integer overflow is undefined behavior.
-  if (E->getType()->isSignedIntegerType())
-    return Builder.CreateNSWNeg(Op, "neg");
-    
+  if (E->getType()->isSignedIntegerType()) {
+    switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
+    case LangOptions::SOB_Trapping:
+      // FIXME: Implement -ftrapv for negate.
+    case LangOptions::SOB_Undefined:
+      return Builder.CreateNSWNeg(Op, "neg");
+    case LangOptions::SOB_Defined:
+      return Builder.CreateNeg(Op, "neg");
+    }
+  }
+  
   return Builder.CreateNeg(Op, "neg");
 }
 
@@ -1397,17 +1413,20 @@ Value *ScalarExprEmitter::EmitOverflowCheckedBinOp(const BinOpInfo &Ops) {
 
 Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
   if (!Ops.Ty->isAnyPointerType()) {
-    if (CGF.getContext().getLangOptions().OverflowChecking &&
-        Ops.Ty->isSignedIntegerType())
-      return EmitOverflowCheckedBinOp(Ops);
-
+    if (Ops.Ty->isSignedIntegerType()) {
+      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
+      case LangOptions::SOB_Undefined:
+        return Builder.CreateNSWAdd(Ops.LHS, Ops.RHS, "add");
+      case LangOptions::SOB_Defined:
+        return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
+      case LangOptions::SOB_Trapping:
+        return EmitOverflowCheckedBinOp(Ops);
+      }
+    }
+    
     if (Ops.LHS->getType()->isFPOrFPVectorTy())
       return Builder.CreateFAdd(Ops.LHS, Ops.RHS, "add");
 
-    // Signed integer overflow is undefined behavior.
-    if (Ops.Ty->isSignedIntegerType())
-      return Builder.CreateNSWAdd(Ops.LHS, Ops.RHS, "add");
-
     return Builder.CreateAdd(Ops.LHS, Ops.RHS, "add");
   }
 
@@ -1473,17 +1492,20 @@ Value *ScalarExprEmitter::EmitAdd(const BinOpInfo &Ops) {
 
 Value *ScalarExprEmitter::EmitSub(const BinOpInfo &Ops) {
   if (!isa<llvm::PointerType>(Ops.LHS->getType())) {
-    if (CGF.getContext().getLangOptions().OverflowChecking
-        && Ops.Ty->isSignedIntegerType())
-      return EmitOverflowCheckedBinOp(Ops);
-
+    if (Ops.Ty->isSignedIntegerType()) {
+      switch (CGF.getContext().getLangOptions().getSignedOverflowBehavior()) {
+      case LangOptions::SOB_Undefined:
+        return Builder.CreateNSWSub(Ops.LHS, Ops.RHS, "sub");
+      case LangOptions::SOB_Defined:
+        return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
+      case LangOptions::SOB_Trapping:
+        return EmitOverflowCheckedBinOp(Ops);
+      }
+    }
+    
     if (Ops.LHS->getType()->isFPOrFPVectorTy())
       return Builder.CreateFSub(Ops.LHS, Ops.RHS, "sub");
 
-    // Signed integer overflow is undefined behavior.
-    if (Ops.Ty->isSignedIntegerType())
-      return Builder.CreateNSWSub(Ops.LHS, Ops.RHS, "sub");
-
     return Builder.CreateSub(Ops.LHS, Ops.RHS, "sub");
   }