On Fri, Aug 31, 2012 at 10:58:51AM -0700, Steve Ellcey wrote:
> Here is my patch to fix the bootstrap comparision failure (PR 54128) on
> MIPS. The reason for the comparision failure was a difference in
> register usage and I tracked it down to build_insn_chain which checked
> all instructions for register usage in order to set the dead_or_set
> and live_relevant_regs bitmaps instead of checking only non-debug
> instructions. Changing INSN_P to NONDEBUG_INSN_P in build_insn_chain
> allowed me to bootstrap and caused no regressions.
The debug insns generally shouldn't extend the lifetime of pseudos (see the
valtrack.c stuff), so if you hit this, there is probably some earlier bug
that didn't reset/adjust the debug insns in question.
I'm not saying the ira.c patch is absolutely a bad idea, but it would be
good if you could investigate where those debug insns started extending
lifetime of pseudos.
> 2012-08-31 Steve Ellcey <sell...@mips.com>
>
> PR bootstrap/54128
> * ira.c (build_insn_chain): Check only NONDEBUG instructions for
> register usage.
Jakub
