Jakub, the testcase g++.dg/opt/mmx2.C you added, causes a segfault on the 4.0 branch:
g++ -O2 -mmmx -c mmx2.C mmx2.C: In function 'int main()': mmx2.C:23: internal compiler error: Segmentation fault Please submit a full bug report, with preprocessed source if appropriate. See <URL:http://gcc.gnu.org/bugs.html> for instructions. This can also be seen in Kaveh's testresults, for example: http://gcc.gnu.org/ml/gcc-testresults/2005-10/msg00523.html http://gcc.gnu.org/ml/gcc-testresults/2005-10/msg01202.html It looks like --enable-checking is required to trigger the bug. As this is a new FAIL in the testsuite, I rate this as a regression. Could you please have a look? -- Summary: [4.0 regression] ICE in g++.dg/opt/mmx2.C Product: gcc Version: 4.0.3 Status: UNCONFIRMED Keywords: ice-on-valid-code, monitored, ice-checking, ssemmx Severity: normal Priority: P2 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: reichelt at gcc dot gnu dot org GCC build triplet: i686-pc-linux-gnu GCC host triplet: i686-pc-linux-gnu GCC target triplet: i686-pc-linux-gnu http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24586
