http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56223
Bug #: 56223
Summary: Integer ABS is not recognized for more complicated
pattern
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ysrum...@gmail.com
In one important benchmark the following ABS pattern which is not recognized by
gcc was found:
if (x >= 0)
s += x;
else
s -= x;
that certainly should be converted to ABS as e.g. icc does.
In result the loop containing this pattern is not vectorized on x86 and arm.
I attached simple test-case to reproduce it.
If we complile it for atom with options " -O3 -m32 -march=atom2 -mtune=atom2
-ffast-math -msse2 -mfpmath=sse -ftree-vectorizer-verbose=2" we got:
...
t5.c:1: note: vectorized 0 loops in function.
...
t5.c:15: note: vectorized 1 loops in function.
