Re: [committed] Minor cleanup/prep in DOM

[Jeff Law <jlaw@ventanamicro.com>]

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On 9/30/22 18:07, H.J. Lu wrote:
> On Fri, Sep 30, 2022 at 4:06 PM Jeff Law <jlaw@ventanamicro.com> wrote:
>>
>> It's a bit weird that free_dom_edge_info leaves a dangling pointer in
>> e->aux.  Not sure what I was thinking.
>>
>>
>> There's two callers.  One wipes e->aux immediately after the call, the
>> other attaches a newly created object immediately after the call.  So we
>> can wipe e->aux within the call and simplify one of the two call sites.
>>
>> This is preparatory work for a minor optimization where we want to
>> detect another class of edge equivalences in DOM (until something better
>> is available) and either attach them an existing edge_info structure or
>> create a new one if one doesn't currently exist for a given edge.
>>
>> Bootstrapped and regression tested on x86_64.  Installing on the trunk.
>>
> I got

[ ... ]

Pushed wrong version.  Sorry about that.  Fixed by attached patch which 
just moves the test down to its proper position.


Jeff



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commit aa360fbf68b11e54017e8fa5b1bdb87ce7c19188
Author: Jeff Law <jeffreyalaw@gmail.com>
Date:   Fri Sep 30 20:46:04 2022 -0400

    Install correct patch version.
    
    gcc/
            * tree-ssa-dom.cc (record_edge_info): Install correct version of
            patch.

diff --git a/gcc/tree-ssa-dom.cc b/gcc/tree-ssa-dom.cc
index 8d8312ca350..e6b8dace5e9 100644
--- a/gcc/tree-ssa-dom.cc
+++ b/gcc/tree-ssa-dom.cc
@@ -684,11 +684,6 @@ record_edge_info (basic_block bb)
 		       !gsi_end_p (gsi);
 		       gsi_next (&gsi))
 		    {
-		      /* If the other alternative is the same as the result,
-			 then this is a degenerate and can be ignored.  */
-		      if (dst == PHI_ARG_DEF (phi, !alternative))
-			continue;
-
 		      /* Now get the EDGE_INFO class so we can append
 			 it to our list.  We want the successor edge
 			 where the destination is not the source of
@@ -697,6 +692,11 @@ record_edge_info (basic_block bb)
 		      tree src = PHI_ARG_DEF (phi, alternative);
 		      tree dst = PHI_RESULT (phi);
 
+		      /* If the other alternative is the same as the result,
+			 then this is a degenerate and can be ignored.  */
+		      if (dst == PHI_ARG_DEF (phi, !alternative))
+			continue;
+
 		      if (EDGE_SUCC (bb, 0)->dest
 			  != EDGE_PRED (bb, !alternative)->src)
 			edge_info = (class edge_info *)EDGE_SUCC (bb, 0)->aux;