When compiling compiler-rt with -fsanitize=undefined and running testcases you
end up with the following warnings:
UBSan: absvdi2.c:21:23: left shift of 1 by 63 places cannot be represented in type 'di_int' (aka 'long long')
UBSan: absvsi2.c:21:23: left shift of 1 by 31 places cannot be represented in type 'si_int' (aka 'long')
UBSan: negvdi2.c:20:32: left shift of 1 by 63 places cannot be represented in type 'di_int' (aka 'long long')
UBSan: negvsi2.c:20:32: left shift of 1 by 31 places cannot be represented in type 'si_int' (aka 'long')
This can be avoided by doing the shift in a matching unsigned variant of the
type.
This was found in an out of tree target.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D146932
COMPILER_RT_ABI di_int __absvdi2(di_int a) {
const int N = (int)(sizeof(di_int) * CHAR_BIT);
- if (a == ((di_int)1 << (N - 1)))
+ if (a == ((di_int)((du_int)1 << (N - 1))))
compilerrt_abort();
const di_int t = a >> (N - 1);
return (a ^ t) - t;
COMPILER_RT_ABI si_int __absvsi2(si_int a) {
const int N = (int)(sizeof(si_int) * CHAR_BIT);
- if (a == ((si_int)1 << (N - 1)))
+ if (a == ((si_int)((su_int)1 << (N - 1))))
compilerrt_abort();
const si_int t = a >> (N - 1);
return (a ^ t) - t;
// Effects: aborts if -a overflows
COMPILER_RT_ABI di_int __negvdi2(di_int a) {
- const di_int MIN = (di_int)1 << ((int)(sizeof(di_int) * CHAR_BIT) - 1);
+ const di_int MIN =
+ (di_int)((du_int)1 << ((int)(sizeof(di_int) * CHAR_BIT) - 1));
if (a == MIN)
compilerrt_abort();
return -a;
// Effects: aborts if -a overflows
COMPILER_RT_ABI si_int __negvsi2(si_int a) {
- const si_int MIN = (si_int)1 << ((int)(sizeof(si_int) * CHAR_BIT) - 1);
+ const si_int MIN =
+ (si_int)((su_int)1 << ((int)(sizeof(si_int) * CHAR_BIT) - 1));
if (a == MIN)
compilerrt_abort();
return -a;