From: Richard Biener <rguenther@suse.de>
Date: Fri, 14 Feb 2020 08:14:42 +0000 (+0100)
Subject: tree-optimization/92704 fix ifcvt ICE with loops without stores
X-Git-Tag: releases/gcc-9.3.0~130
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4230afc0f4f498cc3967bde173c84dde66519711;p=thirdparty%2Fgcc.git

tree-optimization/92704 fix ifcvt ICE with loops without stores

2020-02-14  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	2019-11-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/92704
	* tree-if-conv.c (combine_blocks): Deal with virtual PHIs
	in loops performing only loads.

	* gcc.dg/torture/pr92704.c: New testcase.
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5e79258bfe8c..bfed93eac871 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2020-02-14  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2019-11-29  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/92704
+	* tree-if-conv.c (combine_blocks): Deal with virtual PHIs
+	in loops performing only loads.
+
 2020-02-14  Richard Biener  <rguenther@suse.de>
 
 	Backport from mainline
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 24e5e88d7632..22660ff856e4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2020-02-14  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2019-11-29  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/92704
+	* gcc.dg/torture/pr92704.c: New testcase.
+
 2020-02-13  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/93576
diff --git a/gcc/testsuite/gcc.dg/torture/pr92704.c b/gcc/testsuite/gcc.dg/torture/pr92704.c
new file mode 100644
index 000000000000..79994a39b54b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr92704.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-fexceptions -fnon-call-exceptions -fno-tree-dce -ftree-loop-if-convert" } */
+int zr, yx;
+
+void __attribute__ ((simd))
+oj (int rd, int q7)
+{
+  int wo = (__UINTPTR_TYPE__)&rd;
+
+  while (q7 < 1)
+    {
+      int kv;
+      short int v3;
+
+      for (v3 = 0; v3 < 82; v3 += 3)
+        {
+        }
+
+      kv = zr ? 0 : v3;
+      yx = kv < rd;
+      zr = zr && yx;
+      ++q7;
+    }
+}
diff --git a/gcc/tree-if-conv.c b/gcc/tree-if-conv.c
index 98566e3fd194..2780a4b243fc 100644
--- a/gcc/tree-if-conv.c
+++ b/gcc/tree-if-conv.c
@@ -2626,6 +2626,11 @@ combine_blocks (struct loop *loop)
       vphi = get_virtual_phi (bb);
       if (vphi)
 	{
+	  /* When there's just loads inside the loop a stray virtual
+	     PHI merging the uses can appear, update last_vdef from
+	     it.  */
+	  if (!last_vdef)
+	    last_vdef = gimple_phi_arg_def (vphi, 0);
 	  imm_use_iterator iter;
 	  use_operand_p use_p;
 	  gimple *use_stmt;
@@ -2657,6 +2662,10 @@ combine_blocks (struct loop *loop)
 	      if (gimple_vdef (stmt))
 		last_vdef = gimple_vdef (stmt);
 	    }
+	  else
+	    /* If this is the first load we arrive at update last_vdef
+	       so we handle stray PHIs correctly.  */
+	    last_vdef = gimple_vuse (stmt);
 	  if (predicated[i])
 	    {
 	      ssa_op_iter i;