From: Filip Kastl <fkastl@suse.cz>
Date: Thu, 20 Mar 2025 10:54:59 +0000 (+0100)
Subject: gimple: sccopy: Don't increment i after vec::unordered_remove()
X-Git-Tag: releases/gcc-14.3.0~368
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13950737746e6d6503ad7f1df5a8c47010857ff8;p=thirdparty%2Fgcc.git

gimple: sccopy: Don't increment i after vec::unordered_remove()

I increment the index variable in a loop even when I do
vec::unordered_remove() which causes the vector traversal to miss some
elements.  Mikael notified me of this mistake I made in my last patch.

gcc/ChangeLog:

	* gimple-ssa-sccopy.cc (scc_copy_prop::propagate): Don't
	increment after vec::unordered_remove().

Reported-by: Mikael Morin <mikael@gcc.gnu.org>
Signed-off-by: Filip Kastl <fkastl@suse.cz>
(cherry picked from commit a1363f8dd8037d40e9fbf04c2ba8d6d3e7e5c269)
---

diff --git a/gcc/gimple-ssa-sccopy.cc b/gcc/gimple-ssa-sccopy.cc
index d4d06f3b13e..f7e121992e5 100644
--- a/gcc/gimple-ssa-sccopy.cc
+++ b/gcc/gimple-ssa-sccopy.cc
@@ -554,9 +554,11 @@ sccopy_propagate ()
 	 get removed.  That means parts of CFG get removed.  Those may
 	 contain copy statements.  For that reason we prune SCCs here.  */
       unsigned i;
-      for (i = 0; i < scc.length (); i++)
+      for (i = 0; i < scc.length ();)
 	if (gimple_bb (scc[i]) == NULL)
 	  scc.unordered_remove (i);
+	else
+	  i++;
       if (scc.is_empty ())
 	{
 	  scc.release ();