http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55142
--- Comment #30 from H.J. Lu <hjl.tools at gmail dot com> 2012-11-09 00:35:28 UTC --- (In reply to comment #24) > > I think the most robust solution would be to always zero-extend the addresses > for -mx32, i.e. output > movl %ecx, -1073743664(%eax) > even if the address is a PLUS in DImode. Otherwise, we're left with > kludges... Since x32 runs in 64-bit mode, for address -0x40000300(%rax), hardware sign-extends displacement from 32-bits to 64-bits and adds it to %rax. But x32 wants 32-bit -0x40000300, not 64-bit -0x40000300. I believe it is correct for GCC to use 32-bit registers instead of 64-bit registers when displacement is negative.
