http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58223
Bug ID: 58223 Summary: wrong code at -O3 on x86_64-linux-gnu Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: su at cs dot ucdavis.edu The current gcc trunk (as well as gcc 4.8) produces wrong code for the following testcase on x86_64-linux when compiled at -O3 in both 32-bit and 64-bit modes. This is a regression from 4.7.x. $ gcc-trunk -v gcc version 4.9.0 20130822 (experimental) [trunk revision 201915] (GCC) $ gcc-4.7 -O3 reduced.c $ a.out 1 $ gcc-trunk -O2 reduced.c $ a.out 1 $ gcc-trunk -O3 reduced.c $ a.out 0 $ gcc-4.8 -O3 reduced.c $ a.out 0 $ ------------------------------------------- int printf (const char *, ...); int a[2], b; int main () { for (b = 0; b < 2; b++) { a[0] = 1; a[b] = 0; } printf ("%d\n", a[0]); return 0; }