I see these failures when running the testsuite at -march=i486 (note: execute/ieee means that -mieee-fp is also added to the command line)
FAIL: gcc.c-torture/execute/ieee/20010114-2.c execution, -O1 FAIL: gcc.c-torture/execute/ieee/20010114-2.c execution, -O2 FAIL: gcc.c-torture/execute/ieee/20010114-2.c execution, -Os FAIL: gcc.c-torture/execute/ieee/20030331-1.c execution, -O1 FAIL: gcc.c-torture/execute/ieee/20030331-1.c execution, -O2 FAIL: gcc.c-torture/execute/ieee/20030331-1.c execution, -O3 -fomit-frame-pointer FAIL: gcc.c-torture/execute/ieee/20030331-1.c execution, -O3 -g FAIL: gcc.c-torture/execute/ieee/20030331-1.c execution, -Os -- Summary: rint from gcc.c-torture/execute miscompiled with - march=i486 Product: gcc Version: 4.5.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: bonzini at gnu dot org GCC target triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40130