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Re: revised patch committed.
Ok, I accept the fact I'm on my own here :) at least regarding
zero_extract on set destination.
Let me try and revive this feature so that if any port in the future
use it, it would still work.
So dse does not handle lhs zero_extract, but it's still possible to
work around the problem by treating such zero_extract as wild read in
record_store in
dse.c:
--- dse.c
+++ dse.c
@@ -1301,6 +1301,16 @@
return 0;
mem = SET_DEST (body);
+
+
+ /* bail out in case of ZERO_EXTRACT */
+ if (GET_CODE(mem) == ZERO_EXTRACT)
+ {
+ add_wild_read (bb_info);
+ insn_info->cannot_delete = true;
+ return 0;
+ }
+
/* If this is not used, then this cannot be used to keep the insn
from being deleted. On the other hand, it does provide something
What do you think?
On Thu, Nov 5, 2009 at 6:50 PM, Kenneth Zadeck <zadeck@naturalbridge.com> wrote:
> The main reason that this was missed was that there are no public,
> active ports that actually do this. ?I accepted the patch on Ian
> Taylor's (iant) advice because he said that it was legal as long as the
> mem was a single byte. ? Iant claimed that the last machine that could
> do this kind of thing was the 68k but in his comments he did not
> actually say if the gcc port actually did it. ? Thus, you are really on
> your own as to finding out how much else is broken to support this feature.
>
> When we test new passes, and I admit to being the person who wrote much
> of dse, we test them on the active ports and we fix bugs against those
> ports. ? But a project like gcc is really a use it or loose it kind of
> system. ? The features that are exercised on the public active ports
> work, and the features that are not exercised tend to rot, generally
> until someone adds a new port that utilizes the feature.
>
> I think that the policy is that we accept patches from private ports as
> long as they are fix problems with things that are supposed to work.
> Certainly no one has pushed back on me for accepting your first patch.
>
> Kenny
>