Karl-Johan Karlsson 3032189c0b [compiler-rt] Avoid signed shift overflow in __muloXi4 and __mulvXi3
When compiling compiler-rt with -fsanitize=undefined and running testcases you
end up with the following warning:

UBSan: int_mulo_impl.inc:21:36: left shift of 1 by 63 places cannot be represented in type 'di_int' (aka 'long long')

This can be avoided by simply doing the shift in a matching unsigned variant of
the type.

The same kind of pattern seems to exist in int_mulv_impl.inc

This was found in an out of tree target.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D145556
2023-03-09 08:37:47 +01:00

30 lines
850 B
C

//===-- muloti4.c - Implement __muloti4 -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements __muloti4 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
#ifdef CRT_HAS_128BIT
// Returns: a * b
// Effects: sets *overflow to 1 if a * b overflows
#define fixint_t ti_int
#define fixuint_t tu_int
#include "int_mulo_impl.inc"
COMPILER_RT_ABI ti_int __muloti4(ti_int a, ti_int b, int *overflow) {
return __muloXi4(a, b, overflow);
}
#endif // CRT_HAS_128BIT