Ian Lance Taylor wrote:
Michael Eager <[EMAIL PROTECTED]> writes:I'm trying to understand an assertion failure in reload1.c:8135. In delete_output_reload(), I'm getting an assertion failure in this code: for (i1 = reg_equiv_alt_mem_list [REGNO (reg)]; i1; i1 = XEXP (i1, 1)) { gcc_assert (!rtx_equal_p (XEXP (i1, 0), substed)); n_occurrences += count_occurrences (PATTERN (insn), XEXP (i1, 0), 0); } Sure enough, i1 matches substed. reg_equiv_memory_loc[regno] (the source for substed) is the same as reg_equiv_alt_mem_list[regno]. Why is this unexpected and what might cause it?It's unexpected because you shouldn't see the same memory location in reg_equiv_memory_loc and req_equiv_alt_mem_list. The memory location which holds the value should not also be an alternate location for the value. The check is there because if they are equal for some reason we will miscount occurrences. We already counted occurrences in SUBSTED. I realize that this is probably not very helpful.
:-) I patched the code to only count the occurrence if the locations are different. Any idea if that has adverse consequences?
In case it helps, this is where reg_equiv_alt_mem came in: http://gcc.gnu.org/ml/gcc-patches/2006-07/msg01136.html http://gcc.gnu.org/ml/gcc-patches/2006-08/msg00070.html
Thanks. I think I saw one or perhaps both. I'll look again. Has anyone ever done a description of reg allocation or reload? -- Michael Eager [EMAIL PROTECTED] 1960 Park Blvd., Palo Alto, CA 94306 650-325-8077
