http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50751
--- Comment #7 from Oleg Endo <oleg.e...@t-online.de> 2011-10-26 23:07:08 UTC --- Created attachment 25622 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25622 asmcons and ira pass log for the reload failure of "z" insn constraint (In reply to comment #5) > It seems that clobbering R0 in that expander is simply papering > over the real problem. Yes, it is very much. > Although the reload issue beyonds me, > .ira dump file about that impossible insn which doesn't satisfy > the "z" constraint would be a starting point. I've been trying to make some sense out of it since, but I'm a bit clueless at the moment here. The following function is a reduced failure example: int fail (char* buf0, char* buf1) { char a,b,c; a = buf0[0] + buf1[1]; b = buf0[5] + buf1[4]; c = buf0[15] + buf1[14]; return a+b-c; } In the attached log the problematic pseudo reg is reg:QI 191, where it is reloaded into r1... Reloads for insn # 13 Reload 0: reload_in (QI) = (reg:QI 191 [ MEM[(char *)buf1_4(D) + 4B] ]) reload_out (SI) = (reg:SI 1 r1 [193]) GENERAL_REGS, RELOAD_OTHER (opnum = 0) Strange thing is that the following variant does not cause the error: int fail (char* buf0, char* buf1, char* out) { char a,b,c; a = buf0[0] + buf1[1]; b = buf0[5] + buf1[4]; c = buf0[15] + buf1[14]; *out = a+b-c; return *out; }
