JonChesterfield added a comment. This patch declares the clang builtin as acting on signed values, but the IR intrinsic maps to an instruction which does an unsigned comparison. We don't have ISA support for a signed comparison equivalent. Addition is the same operation on signed or unsigned integers, but signed integer comparison is not equivalent to unsigned integer comparison.
// 32bit tmp = MEM[ADDR]; MEM[ADDR] = (tmp >= DATA) ? 0 : tmp + 1; // unsigned compare RETURN_DATA = tmp. The builtins should be changed to take unsigned values, optionally making that clear from the naming scheme, perhaps `__amdgcn_builtin_atomic_dec_u32`. Apologies for not reviewing this the first time around. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D80804/new/ https://reviews.llvm.org/D80804 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
