http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58853
--- Comment #7 from Jan Hubicka <hubicka at ucw dot cz> --- > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c > index 53e04c4..dd8d943 100644 > --- a/gcc/config/i386/i386.c > +++ b/gcc/config/i386/i386.c > @@ -23766,6 +23766,7 @@ ix86_expand_set_or_movmem (rtx dst, rtx src, rtx > count_exp, rtx > val_exp, > also avoids redundant job when sizes are known precisely. */ > misaligned_prologue_used = (TARGET_MISALIGNED_MOVE_STRING_PROLOGUES > && MAX (desired_align, epilogue_size_needed) <= 32 > + && desired_align <= epilogue_size_needed > && ((desired_align > align && !align_bytes) > || (!count && epilogue_size_needed > 1))); > > avoids crash. Yes, we can add this, too, for correctness with manual changes to tunning flags (so the patch is approved). What confuses me is why TARGET_MISALIGNED_MOVE_STRING_PROLOGUES seems to be true given that DEF_TUNE (TARGET_MISALIGNED_MOVE_STRING_PROLOGUES, "misaligned_move_string_prologues", m_386 | m_486 | m_CORE_ALL | m_AMD_MULTIPLE | m_GENERIC) and we tune for pentiumpro (that was intentionally left out for this purpose) Honza