[compiler-rt] 854686f - [compiler-rt] Fix signed shift overflows in absvdi2.c, absvsi2.c, negvdi2.c and negvsi2.c

[Karl-Johan Karlsson via llvm-commits]

Author: Karl-Johan Karlsson
Date: 2023-04-14T07:45:13+02:00
New Revision: 854686f0794b9d0695d5a0a85ea1e7e71ba8edfd

URL: https://github.com/llvm/llvm-project/commit/854686f0794b9d0695d5a0a85ea1e7e71ba8edfd
DIFF: https://github.com/llvm/llvm-project/commit/854686f0794b9d0695d5a0a85ea1e7e71ba8edfd.diff

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

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

Added: 
    

Modified: 
    compiler-rt/lib/builtins/absvdi2.c
    compiler-rt/lib/builtins/absvsi2.c
    compiler-rt/lib/builtins/negvdi2.c
    compiler-rt/lib/builtins/negvsi2.c

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/builtins/absvdi2.c b/compiler-rt/lib/builtins/absvdi2.c
index b9566cd874fe4..291ab5f7f91d5 100644
--- a/compiler-rt/lib/builtins/absvdi2.c
+++ b/compiler-rt/lib/builtins/absvdi2.c
@@ -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;

diff  --git a/compiler-rt/lib/builtins/absvsi2.c b/compiler-rt/lib/builtins/absvsi2.c
index 9d5de7e8a3f22..9977c33d8f7ea 100644
--- a/compiler-rt/lib/builtins/absvsi2.c
+++ b/compiler-rt/lib/builtins/absvsi2.c
@@ -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;

diff  --git a/compiler-rt/lib/builtins/negvdi2.c b/compiler-rt/lib/builtins/negvdi2.c
index 5c52b3ec2aa60..8c1cf2fa58d46 100644
--- a/compiler-rt/lib/builtins/negvdi2.c
+++ b/compiler-rt/lib/builtins/negvdi2.c
@@ -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;

diff  --git a/compiler-rt/lib/builtins/negvsi2.c b/compiler-rt/lib/builtins/negvsi2.c
index cccdee6dc5e55..70f214f9761d8 100644
--- a/compiler-rt/lib/builtins/negvsi2.c
+++ b/compiler-rt/lib/builtins/negvsi2.c
@@ -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;