From: Richard Biener <rguenther@suse.de>
Date: Wed, 29 Mar 2023 09:59:16 +0000 (+0200)
Subject: tree-optimization/109331 - make sure to clean up the CFG after forwprop
X-Git-Tag: basepoints/gcc-14~279
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=86efc490ab86bfa00720479b4714da23cd7df797;p=thirdparty%2Fgcc.git

tree-optimization/109331 - make sure to clean up the CFG after forwprop

When forwprop discovers unreachable code or makes decisions based
on unreachable edges make sure to cleanup the CFG since otherwise
SSA form can become invalid.

	PR tree-optimization/109331
	* tree-ssa-forwprop.cc (pass_forwprop::execute): When we
	discover a taken edge make sure to cleanup the CFG.

	* gcc.dg/torture/pr109331.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/torture/pr109331.c b/gcc/testsuite/gcc.dg/torture/pr109331.c
new file mode 100644
index 000000000000..72c57b9b74ca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr109331.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+char *ustol_dpp;
+void ustol(int flags)
+{
+  char *s;
+  if (s)
+    flags |= 3;
+  switch (flags & 3)
+  case 3:
+    while (*s)
+    case '+':
+      ++s;
+  if (flags)
+    ustol_dpp = s;
+}
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index bb0fa306312f..9b567440ba4f 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -4046,7 +4046,11 @@ pass_forwprop::execute (function *fun)
 
       /* Mark outgoing exectuable edges.  */
       if (edge e = find_taken_edge (bb, NULL))
-	e->flags |= EDGE_EXECUTABLE;
+	{
+	  e->flags |= EDGE_EXECUTABLE;
+	  if (EDGE_COUNT (bb->succs) > 1)
+	    cfg_changed = true;
+	}
       else
 	{
 	  FOR_EACH_EDGE (e, ei, bb->succs)