Using MMX bultins in a sizeable but not extreme function leads to exponential compile time.
Attached code will take an excessive compile time [I think hours]. Similar code using SSE compiles quickly for me. $ gcc --version gcc (GCC) 4.3.2 20081007 (Red Hat 4.3.2-6) Copyright (C) 2008 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. -- Summary: Exponential compile time with MMX builtins. Product: gcc Version: 4.3.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: suckfish at ihug dot co dot nz GCC build triplet: x86-64 GCC host triplet: x86-64 GCC target triplet: x86-64 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37807