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Re: [PATCH,RFC] CSE path following on basic blocks


Steven Bosscher wrote:
On 11/28/06, Eric Botcazou <ebotcazou@libertysurf.fr> wrote:
!   /* There is a previous path.  Make sure it started with FIRST_BB.  */
!   if (path_size)
!     gcc_assert (data->path[0].bb = first_bb);

Not sure what you're trying to do here. Or maybe an annoying typo?

If there is a path in data, then we're going to discover a new path starting with data->path[0].bb. But Passing first_bb may be unnecessary.

But you have only one '=' above... :-)


Yes.  Left-over from testing.  I sometimes ended up with path_size < 0
due to a bug.  I'll remove this in the final patch submission.

Or assert path_size >= 0 nearer to the beginning of the functions.


I'm not sure if we want to do this, though.  We could follow the
fallthrough path even if flag_cse_follow_jumps is not set (which is
indeed what CSE currently does). Or we could make CSE purely a local
(i.e. intra basic block) pass if flag_cse_follow_jumps is not set.
Personally, I don't think it matters much, but making it purely local
is slightly easier and a lot more consistent.

FWIW, I agree with Steven.


*************** cse_insn (rtx insn, rtx libcall_insn)
*** 5647,5652 ****
--- 5652,5659 ----
   prev_insn_cc0_mode = this_insn_cc0_mode;
   prev_insn = insn;
 #endif
+
+   return;
 }

Rather clever attempt to grow the size of the patch. :-)

Actually, without this you get a warning about a label at the end of a compound statement on CC0-targets. I found that out the hard way.

Then you could also replace "label:" with "label:;"


Paolo


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