https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108397
Bug ID: 108397
Summary: Missed optimization with [0, 0][-1U,-1U] range
arithmetics
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: jakub at gcc dot gnu.org
CC: hjl.tools at gmail dot com, jakub at gcc dot gnu.org,
marxin at gcc dot gnu.org, rguenth at gcc dot gnu.org,
unassigned at gcc dot gnu.org, uros at gcc dot gnu.org,
yinyuefengyi at gmail dot com, zsojka at seznam dot cz
Depends on: 107131
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: x86_64-pc-linux-gnu
+++ This bug was initially created as a clone of Bug #107131 +++
__attribute__((noipa)) unsigned long long
foo (unsigned char o)
{
unsigned long long t1 = -(long long) (o == 0);
unsigned long long t2 = -(long long) (t1 > 10439075533421201520ULL);
unsigned long long t3 = -(long long) (t1 <= t2);
return t3;
}
from comment 8 of that PR could be optimized into return -1ULL.
t1 has range [0,0][-1ULL,-1ULL], t2 is set to 0 if t1 is 0 and to -1ULL if t1
is -1ULL
and thus t2 could be optimized to t2 = t1. And t1 <= t2 can then trivially
fold to
t1 <= t1 aka true.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107131
[Bug 107131] [11/12 Regression] wrong code with -Os -fno-ipa-vrp
-fno-tree-bit-ccp
