From: Tamar Christina <tamar.christina@arm.com>
Date: Thu, 4 Aug 2022 15:35:31 +0000 (+0100)
Subject: middle-end: Fix phi-ssa assertion triggers.  [PR106519]
X-Git-Tag: basepoints/gcc-14~5244
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c832ec4c3ec4853ad89ff3b0dbf6e9454e75e8cc;p=thirdparty%2Fgcc.git

middle-end: Fix phi-ssa assertion triggers.  [PR106519]

For the diamond PHI form in tree_ssa_phiopt_worker we need to
extract edge e2 sooner.  This changes it so we extract it at the
same time we determine we have a diamond shape.

gcc/ChangeLog:

	PR middle-end/106519
	* tree-ssa-phiopt.cc (tree_ssa_phiopt_worker): Check final phi edge for
	diamond shapes.

gcc/testsuite/ChangeLog:

	PR middle-end/106519
	* gcc.dg/pr106519.c: New test.
---

diff --git a/gcc/testsuite/gcc.dg/pr106519.c b/gcc/testsuite/gcc.dg/pr106519.c
new file mode 100644
index 00000000000..3d4662d8a02
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr106519.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+
+int bytestart, bytemem_0_0, modlookup_l_p;
+
+void
+modlookup_l() {
+  long j;
+  while (modlookup_l_p)
+    while (bytestart && j && bytemem_0_0)
+      j = j + 1;
+}
diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index a8e55e04064..ef4c0b78f4e 100644
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -269,7 +269,10 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 	}
       else if (EDGE_SUCC (bb1, 0)->dest == EDGE_SUCC (bb2, 0)->dest
 	       && !empty_block_p (bb1))
-	diamond_p = true;
+	{
+	  diamond_p = true;
+	  e2 = EDGE_SUCC (bb2, 0);
+	}
       else
 	continue;
 
@@ -324,7 +327,6 @@ tree_ssa_phiopt_worker (bool do_store_elim, bool do_hoist_loads, bool early_p)
 	  if (!candorest)
 	    continue;
 
-	  e2 = diamond_p ? EDGE_SUCC (bb2, 0) : e2;
 	  phi = single_non_singleton_phi_for_edges (phis, e1, e2);
 	  if (!phi)
 	    continue;