1295aa2e81
GCC supports three flags related to overflow behavior: * `-fwrapv`: Makes signed integer overflow well-defined. * `-fwrapv-pointer`: Makes pointer overflow well-defined. * `-fno-strict-overflow`: Implies `-fwrapv -fwrapv-pointer`, making both signed integer overflow and pointer overflow well-defined. Clang currently only supports `-fno-strict-overflow` and `-fwrapv`, but not `-fwrapv-pointer`. This PR proposes to introduce `-fwrapv-pointer` and adjust the semantics of `-fwrapv` to match GCC. This allows signed integer overflow and pointer overflow to be controlled independently, while `-fno-strict-overflow` still exists to control both at the same time (and that option is consistent across GCC and Clang).
13 lines
650 B
C
13 lines
650 B
C
// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s --check-prefix=DEFAULT
|
|
// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -fwrapv | FileCheck %s --check-prefix=DEFAULT
|
|
// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -ftrapv | FileCheck %s --check-prefix=DEFAULT
|
|
// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -fwrapv-pointer | FileCheck %s --check-prefix=FWRAPV-POINTER
|
|
|
|
void test(void) {
|
|
// -fwrapv-pointer should turn off inbounds for GEP's
|
|
extern int* P;
|
|
++P;
|
|
// DEFAULT: getelementptr inbounds nuw i32, ptr
|
|
// FWRAPV-POINTER: getelementptr i32, ptr
|
|
}
|