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[compiler-rt] Fix signed shift overflows in absvdi2.c, absvsi2.c, negvdi2.c and negvsi2.c

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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
This commit is contained in:
Karl-Johan Karlsson
2023-04-14 07:44:44 +02:00
parent fb77ca05ff
commit 854686f079
4 changed files with 6 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
compiler-rt/lib/builtins/absvdi2.c
View File

@@ -18,7 +18,7 @@
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;

2
compiler-rt/lib/builtins/absvsi2.c
View File

@@ -18,7 +18,7 @@
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;

3
compiler-rt/lib/builtins/negvdi2.c
View File

@@ -17,7 +17,8 @@
// 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;

3
compiler-rt/lib/builtins/negvsi2.c
View File

@@ -17,7 +17,8 @@
// 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;