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[builtins] Fix signed shift overflows in absvti2.c and negvti2.c

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When compiling the builtins with the undefined behavior sanitizer and running testcases you end up with the following warning:

UBSan: negvti2.c:22:32: left shift of 1 by 127 places cannot be represented in type 'ti_int' (aka '__int128')
UBSan: absvti2.c:23:23: left shift of 1 by 127 places cannot be represented in type 'ti_int' (aka '__int128')

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

This is the same kind of fixes that already was done in commit
854686f0794b9d0695d5a0a85ea1e7e71ba8edfd

This was found in an out of tree target.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D158816
This commit is contained in:
Karl-Johan Karlsson 2023-08-28 06:13:16 +02:00
parent 4198576157
commit 56255e0421
2 changed files with 2 additions and 2 deletions
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2
compiler-rt/lib/builtins/absvti2.c
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@ -20,7 +20,7 @@
COMPILER_RT_ABI ti_int __absvti2(ti_int a) {
const int N = (int)(sizeof(ti_int) * CHAR_BIT);
if (a == ((ti_int)1 << (N - 1)))
if (a == (ti_int)((tu_int)1 << (N - 1)))
compilerrt_abort();
const ti_int s = a >> (N - 1);
return (a ^ s) - s;

2
compiler-rt/lib/builtins/negvti2.c
View File

@ -19,7 +19,7 @@
// Effects: aborts if -a overflows
COMPILER_RT_ABI ti_int __negvti2(ti_int a) {
const ti_int MIN = (ti_int)1 << ((int)(sizeof(ti_int) * CHAR_BIT) - 1);
const ti_int MIN = (tu_int)1 << ((int)(sizeof(ti_int) * CHAR_BIT) - 1);
if (a == MIN)
compilerrt_abort();
return -a;