In the CBackend, use casts to force integer add, subtract, and
multiply to be done as unsigned, so that they have well defined
behavior on overflow. This fixes PR2408.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 71895f4..34511e8 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -1116,6 +1116,13 @@
const Type *Ty = CE->getOperand(0)->getType();
bool TypeIsSigned = false;
switch (CE->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!Ty->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::URem:
case Instruction::UDiv: NeedsExplicitCast = true; break;
@@ -1174,6 +1181,13 @@
default:
// for most instructions, it doesn't matter
break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!OpTy->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::UDiv:
case Instruction::URem:
@@ -1294,6 +1308,13 @@
bool CWriter::writeInstructionCast(const Instruction &I) {
const Type *Ty = I.getOperand(0)->getType();
switch (I.getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!Ty->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::URem:
case Instruction::UDiv:
@@ -1334,6 +1355,13 @@
default:
// for most instructions, it doesn't matter
break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!OpTy->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::UDiv:
case Instruction::URem: // Cast to unsigned first