https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65307
Bug ID: 65307
Summary: Incorrect optimization breaks basic arithmetic
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: madars+gccbug at gmail dot com
The following code sample exhibits a bug in a gcc -O2 optimization pass.
Namely, having defined two() and six() with the obvious return values, the
value of two() * 2 + six() * 5 gets an assembly of 1 shl 5 (i.e. 32, instead of
the correct 34).
Code: http://web.mit.edu/madars/Public/gcc-basic-arithmetic-bug.c
gcc 4.9.1 and 4.9.2 with -O2 are both buggy, -O1 makes the bug go away; the bug
does not seem to be present in gcc 4.8 and earlier.
