> The problem shows in loop-doloop.c when I introduce a loop end pattern > that replaces the first jump instruction (JUMP_INSN 15) with a pattern > that clobbers CC reg. However, the DF doesn't look like it works as > the doloop step cannot find the CC reg alive. Please see > loop-doloop.c:766. Hence, it introduces the doloop_end patterns, and > renders the compare instruction (INSN 14) dead code. leading to > errors.
So df_get_live_out does not contain the CC register? iv_analysis_loop_init only performs a local update of the DF information, maybe it does not cover the basic block containing insn 14 and 15? -- Eric Botcazou
