Re: ifcvt/crossjump patch: Fix PR 42496, 21803

[Bernd Schmidt <bernds at codesourcery dot com>]

On 08/02/2010 06:15 PM, Bernd Schmidt wrote:
> On 08/02/2010 06:05 PM, Jeff Law wrote:
>> OK.  If you could highlight in a quick blurb what changed it'd be
>> appreciated -- it'll save me from having to look over the whole thing
>> again to figure out what changed from the previous version.
> 
> I intend to make the change I previously mentioned to add a per-bb flag
> which notes it's been modified, so that we can use that on the second
> pass to decide whether or not to try to optimize it, rather than using
> df_get_bb_dirty (since that gets cleared on df_analyze).  Earlier
> versions of gcc had a BB_DIRTY bit in bb->flags, I'll reintroduce that
> as BB_MODIFIED.  That's cheaper to test anyway.
> 
> The other change I'll make is to be slightly more careful wrt. volatile
> asms, not moving memory references across them.

Did that, and also fixed a crash I saw with a PPC cross compiler -
mustn't try to look at insns in EXIT_BLOCK.  Note that there's still a
call to clear_bb_flags which I think is left over from before we were
using df_get_bb_dirty and now has a purpose again.

New patch below; search for BB_MODIFIED, ASM_OPERANDS and EXIT_BLOCK_PTR
to find these changes.  Also, added the two testcases for i386 as well
and Paolo's suggestion of a gcc_assert before df_analyze.

Bootstrapped and regression tested on i686-linux.


Bernd

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