Re: [PATCH] ipa: silent -Wodr notes with -w

[Jan Hubicka <hubicka@ucw.cz>]

> > On 2/1/23 15:26, Martin Jambor wrote:
> > > Hi,
> > > 
> > > On Fri, Dec 02 2022, Martin Liška wrote:
> > > > If -w is used, warn_odr properly sets *warned = false and
> > > > so it should be preserved when calling warn_types_mismatch.
> > > > 
> > > > Noticed that during a LTO reduction where I used -w.
> > > > 
> > > > Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> > > > 
> > > > Ready to be installed?
> > > > Thanks,
> > > > Martin
> > > > 
> > > > gcc/ChangeLog:
> > > > 
> > > > 	* ipa-devirt.cc (odr_types_equivalent_p): Respect *warned
> > > > 	value if set.
> > > 
> > 
> > Hi.
> > 
> > > Sorry for skipping this for so long, usually ODR stuff is... interesting
> > > to the point I gladly leave it to Honza.
> > 
> > Makes sense, however, he's not much active when it comes to patch review.
> 
> Sorry, I was confused by the patch and delayed reply to figure out what
> you are trying to fix.  Indeed the dererence is missing here, however
> every caller that sets warn to true should also set warned to non-NULL.
> So indeed derefernce is missing, but I think the check for
> warned == NULL should not be necessary.

This seems to bootstrap with LTO.  I am not sure what testcase you
looked in, but unless there as a good reason to include the NULL check,
I would rmeove it as it makes it harder to see what is going on.

honza

diff --git a/gcc/ipa-devirt.cc b/gcc/ipa-devirt.cc
index 14cf132c767..819860258d1 100644
--- a/gcc/ipa-devirt.cc
+++ b/gcc/ipa-devirt.cc
@@ -1221,6 +1221,9 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 			hash_set<type_pair> *visited,
 			location_t loc1, location_t loc2)
 {
+  /* If we are asked to warn, we need warned to keep track if warning was
+     output.  */
+  gcc_assert (!warn || warned);
   /* Check first for the obvious case of pointer identity.  */
   if (t1 == t2)
     return true;
@@ -1300,7 +1303,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 	      warn_odr (t1, t2, NULL, NULL, warn, warned,
 			G_("it is defined as a pointer to different type "
 			   "in another translation unit"));
-	      if (warn && (warned == NULL || *warned))
+	      if (warn && *warned)
 	        warn_types_mismatch (TREE_TYPE (t1), TREE_TYPE (t2),
 				     loc1, loc2);
 	      return false;
@@ -1315,7 +1318,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 	  warn_odr (t1, t2, NULL, NULL, warn, warned,
 		    G_("a different type is defined "
 		       "in another translation unit"));
-	  if (warn && (warned == NULL || *warned))
+	  if (warn && *warned)
 	    warn_types_mismatch (TREE_TYPE (t1), TREE_TYPE (t2), loc1, loc2);
 	  return false;
 	}
@@ -1333,7 +1336,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 	    warn_odr (t1, t2, NULL, NULL, warn, warned,
 		      G_("a different type is defined in another "
 			 "translation unit"));
-	    if (warn && (warned == NULL || *warned))
+	    if (warn && *warned)
 	      warn_types_mismatch (TREE_TYPE (t1), TREE_TYPE (t2), loc1, loc2);
 	  }
 	gcc_assert (TYPE_STRING_FLAG (t1) == TYPE_STRING_FLAG (t2));
@@ -1375,7 +1378,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 	  warn_odr (t1, t2, NULL, NULL, warn, warned,
 		    G_("has different return value "
 		       "in another translation unit"));
-	  if (warn && (warned == NULL || *warned))
+	  if (warn && *warned)
 	    warn_types_mismatch (TREE_TYPE (t1), TREE_TYPE (t2), loc1, loc2);
 	  return false;
 	}
@@ -1398,7 +1401,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 		  warn_odr (t1, t2, NULL, NULL, warn, warned,
 			    G_("has different parameters in another "
 			       "translation unit"));
-		  if (warn && (warned == NULL || *warned))
+		  if (warn && *warned)
 		    warn_types_mismatch (TREE_VALUE (parms1),
 					 TREE_VALUE (parms2), loc1, loc2);
 		  return false;
@@ -1484,7 +1487,7 @@ odr_types_equivalent_p (tree t1, tree t2, bool warn, bool *warned,
 		    warn_odr (t1, t2, f1, f2, warn, warned,
 			      G_("a field of same name but different type "
 				 "is defined in another translation unit"));
-		    if (warn && (warned == NULL || *warned))
+		    if (warn && *warned)
 		      warn_types_mismatch (TREE_TYPE (f1), TREE_TYPE (f2), loc1, loc2);
 		    return false;
 		  }