f0bbda00bd
Currenly both Clang and GCC support the following set of flags that control code gen of signed overflow: * -fwrapv: overflow is defined as in two-complement * -ftrapv: overflow traps * -fsanitize=signed-integer-overflow: if undefined (no -fwrapv), then overflow behaviour is controlled by UBSan runtime, overrides -ftrapv Howerver, clang ignores these flags for __builtin_abs(int) and its higher-width versions, so passing minimum integer value always causes poison. The same holds for *abs(), which are not handled in frontend at all but folded to llvm.abs.* intrinsics during InstCombinePass. The intrinsics are not instrumented by UBSan, so the functions need special handling as well. This patch does a few things: * Handle *abs() in CGBuiltin the same way as __builtin_*abs() * -fsanitize=signed-integer-overflow now properly instruments abs() with UBSan * -fwrapv and -ftrapv handling for abs() is made consistent with GCC Fixes #45129 and #45794 Reviewed By: efriedma, MaskRay Differential Revision: https://reviews.llvm.org/D156821
Compiler-RT ================================ This directory and its subdirectories contain source code for the compiler support routines. Compiler-RT is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt. ================================