[Bug target/32437] [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c

zadeck at naturalbridge dot com gcc-bugzilla@gcc.gnu.org
Sun Jul 1 14:45:00 GMT 2007

------- Comment #24 from zadeck at naturalbridge dot com  2007-07-01 14:45 -------
Subject: Re:  [4.3 Regression] MIPS: FAIL in gcc.dg/cleanup-[8|9|10|11].c

ian at airs dot com wrote:
> ------- Comment #23 from ian at airs dot com  2007-06-30 17:57 -------
> The patch in comment #19 of PR 32437 looks clearly correct.  That
> patch should not be reverted, at least not by itself.  I'm not clear
> on whether that was the patch that was reverted, but, if it was, I
> don't think it should have been.  We are not in a time critical
> situation here.  Let's take the time to figure out the right fix even
> if Richard doesn't have time to work on it.
> This is DCE, not DSE.  In DSE we can not eliminate frame related
> instructions, because the stores into the frame are used by code which
> dataflow doesn't see: the exception unwinder.  That does not apply to
> DCE.  In DCE, we should be able to eliminate changes to the stack
> pointer when the stack pointer is not used, even though those changes
> are frame related.
> So I think this patch should be unreverted, and I don't think you should add a
> test for frame relatedness.  Then we should fix PR 32475.  Further comments
> over there.
2007-07-01  Richard Sandiford  <richard@codesourcery.com>

    Unreverting Richard's Revert of:

    2007-06-27  Richard Sandiford  <richard@codesourcery.com>

    * dce.c (deletable_insn_p_1): New function, split out from...
    (deletable_insn_p): ...here.  Only treat bare USEs and CLOBBERs
    specially, not those inside PARALLELs.  Remove BODY argument
    and adjust recursive call accordingly.
    (prescan_insns_for_dce): Update call to delete_insn_p.



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