http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55147
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2012-10-31 CC| |jakub at gcc dot gnu.org, | |uros at gcc dot gnu.org Ever Confirmed|0 |1 --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-10-31 15:37:49 UTC --- --- gcc/config/i386/i386.md.jj 2012-10-30 09:01:15.000000000 +0100 +++ gcc/config/i386/i386.md 2012-10-31 16:25:13.986916767 +0100 @@ -12688,7 +12688,14 @@ (define_insn_and_split "*bswapdi2_double (set (match_dup 0) (bswap:SI (match_dup 3)))] { - split_double_mode (DImode, &operands[0], 2, &operands[0], &operands[2]); + split_double_mode (DImode, &operands[0], 1, &operands[0], &operands[2]); + if (MEM_P (operands[1]) + && reg_overlap_mentioned_p (operands[2], operands[1])) + { + emit_insn (gen_rtx_SET (VOIDmode, operands[0], XEXP (operands[1], 0))); + operands[1] = change_address (operands[1], VOIDmode, operands[0]); + } + split_double_mode (DImode, &operands[1], 1, &operands[1], &operands[3]); if (REG_P (operands[0]) && REG_P (operands[1])) { can fix the reg overlap problem between address of operands[1] and high part of operands[0]. That said, I wonder what is the advantage of having bswapdi2 patter on i?86 at all that the generic expand_doubleword_bswap can't handle.