From: Jan Hubicka <hubicka@ucw.cz>
Date: Tue, 27 Jan 2026 18:18:13 +0000 (+0100)
Subject: Remove impossible speculation in ipa_polymorphic_call_context::possible_dynamic_type_... 
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fe050fa9d1249a7a528a30a499d1abc23f47f2c8;p=thirdparty%2Fgcc.git

Remove impossible speculation in ipa_polymorphic_call_context::possible_dynamic_type_change

This patch makes ipa-cp dataflow monotone by making sure we do not use speculation that
was proved to be impossible earlier.

gcc/ChangeLog:

	PR ipa/123619
	* ipa-polymorphic-call.cc
	(ipa_polymorphic_call_context::possible_dynamic_type_change): Remove impossible
	speuculation.
---

diff --git a/gcc/ipa-polymorphic-call.cc b/gcc/ipa-polymorphic-call.cc
index 243a2f13cdc..5e53c217e33 100644
--- a/gcc/ipa-polymorphic-call.cc
+++ b/gcc/ipa-polymorphic-call.cc
@@ -2363,7 +2363,18 @@ ipa_polymorphic_call_context::possible_dynamic_type_change (bool in_poly_cdtor,
 							    tree otr_type)
 {
   if (dynamic)
-    make_speculative (otr_type);
+    {
+      /* See if existing speculation was inconsistent before type change.
+	 If so drop it first, so we do not lose track about it being
+	 impossible.  */
+      if (speculative_outer_type
+	  && !speculation_consistent_p (speculative_outer_type,
+					speculative_offset,
+					speculative_maybe_derived_type,
+					otr_type))
+	clear_speculation ();
+      make_speculative (otr_type);
+    }
   else if (in_poly_cdtor)
     maybe_in_construction = true;
 }