diff options
| -rw-r--r-- | lib/CodeGen/CGExprScalar.cpp | 8 | ||||
| -rw-r--r-- | test/CodeGen/integer-overflow.c | 8 |
2 files changed, 12 insertions, 4 deletions
diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp index c4ff8df381..b11236a97f 100644 --- a/lib/CodeGen/CGExprScalar.cpp +++ b/lib/CodeGen/CGExprScalar.cpp @@ -1278,10 +1278,12 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV, llvm::Value *amt = llvm::ConstantInt::get(value->getType(), amount); - if (type->isSignedIntegerType()) + // Note that signed integer inc/dec with width less than int can't + // overflow because of promotion rules; we're just eliding a few steps here. + if (type->isSignedIntegerType() && + value->getType()->getPrimitiveSizeInBits() >= + CGF.CGM.IntTy->getBitWidth()) value = EmitAddConsiderOverflowBehavior(E, value, amt, isInc); - - // Unsigned integer inc is always two's complement. else value = Builder.CreateAdd(value, amt, isInc ? "inc" : "dec"); diff --git a/test/CodeGen/integer-overflow.c b/test/CodeGen/integer-overflow.c index 066ef89574..1d460656a1 100644 --- a/test/CodeGen/integer-overflow.c +++ b/test/CodeGen/integer-overflow.c @@ -50,11 +50,17 @@ void test1() { // TRAPV_HANDLER: foo( --a; - // -fwrapv should turn off inbounds for GEP's, PR9256 extern int* P; ++P; // DEFAULT: getelementptr inbounds i32* // WRAPV: getelementptr i32* // TRAPV: getelementptr inbounds i32* + + // PR9350: char increment never overflows. + extern volatile signed char PR9350; + // DEFAULT: add i8 {{.*}}, 1 + // WRAPV: add i8 {{.*}}, 1 + // TRAPV: add i8 {{.*}}, 1 + ++PR9350; } |