From: Jan Hubicka <hubicka@ucw.cz>
Date: Sun, 15 Feb 2026 19:19:57 +0000 (+0100)
Subject: Disable simpe-call devirtualization of already devirtualized calls
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8cf191e93763ee9c00b5bed4092a426c7761362b;p=thirdparty%2Fgcc.git

Disable simpe-call devirtualization of already devirtualized calls

Fix ICE caused by speculating already speculated target with auto-fdo.
ipa_devirt is supposed to consistently skip devirtualized edges (or just check
if devirtualization agrees with the static prediction when dumping).  This was
not hecked correctly in the simpe call path.

gcc/ChangeLog:

	* ipa-devirt.cc (ipa_devirt): Improve statistics for multi-target
	devirtualization; do not simple-call devirtualize already devirtualized calls.
---

diff --git a/gcc/ipa-devirt.cc b/gcc/ipa-devirt.cc
index a7cb2697813..8577e9b30fb 100644
--- a/gcc/ipa-devirt.cc
+++ b/gcc/ipa-devirt.cc
@@ -3845,23 +3845,21 @@ ipa_devirt (void)
  	       with the speculation.  */
 	    if (e->speculative)
 	      {
-		bool found = false;
 		for (cgraph_node * likely_target: likely_targets)
 		  if (e->speculative_call_for_target (likely_target))
 		    {
-		      found = true;
-		      break;
+		      fprintf (dump_file,
+			       "We agree with speculation on target %s\n\n",
+			       likely_target->dump_name ());
+		      stats.nok++;
+		    }
+		  else
+		    {
+		      fprintf (dump_file,
+			       "We disagree with speculation on target %s\n\n",
+			       likely_target->dump_name ());
+		      stats.nwrong++;
 		    }
-		if (found)
-		  {
-		    fprintf (dump_file, "We agree with speculation\n\n");
-		    stats.nok++;
-		  }
-		else
-		  {
-		    fprintf (dump_file, "We disagree with speculation\n\n");
-		    stats.nwrong++;
-		  }
 		continue;
 	      }
 	    bool first = true;
@@ -3908,6 +3906,16 @@ ipa_devirt (void)
 	else if (cgraph_simple_indirect_info *sii
 		 = dyn_cast <cgraph_simple_indirect_info *> (e->indirect_info))
 	  {
+	    if (e->speculative)
+	      {
+		if (dump_file)
+		  fprintf (dump_file, "Call is already speculated\n\n");
+		stats.nspeculated++;
+
+		/* When dumping see if we agree with speculation.  */
+		if (!dump_file)
+		  continue;
+	      }
 	    if (!sii->fnptr_loaded_from_record
 		|| !opt_for_fn (n->decl,
 				flag_speculatively_call_stored_functions))
@@ -3930,6 +3938,20 @@ ipa_devirt (void)
 		    if (alias)
 		      likely_tgt_node = alias;
 		  }
+		if (e->speculative)
+		  {
+		    if (e->speculative_call_for_target (likely_tgt_node))
+		      {
+			fprintf (dump_file, "Simple call agree with speculation\n\n");
+			stats.nok++;
+		      }
+		    else
+		      {
+			fprintf (dump_file, "Simple call disagree with speculation\n\n");
+			stats.nwrong++;
+		      }
+		    continue;
+		  }
 
 		if (dump_enabled_p ())
 		  dump_printf_loc (MSG_OPTIMIZED_LOCATIONS, e->call_stmt,