re PR tree-optimization/86865 (Wrong code w/ -O2 -floop-parallelize-all -fstack-reuse=none -fwrapv -fno-tree-ch -fno-tree-dce -fno-tree-dominator-opts -fno-tree-loop-ivcanon)

2019-01-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/86865
	* graphite-scop-detection.c (scop_detection::can_represent_loop):
	Reject non-do-while loops.

	* gcc.dg/graphite/pr86865.c: New testcase.
	* gcc.dg/graphite/pr69728.c: XFAIL.
	* gcc.dg/graphite/scop-21.c: Likewise.

From-SVN: r268257

6 files changed, 62 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7156b64dc1d..bdcd4739fa4 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86865
+	* graphite-scop-detection.c (scop_detection::can_represent_loop):
+	Reject non-do-while loops.
+
 2019-01-24  Peter Bergner  <bergner@linux.ibm.com>
 
 	* config/rs6000/altivec.md (build_vector_mask_for_load): Use MEM_P.
diff --git a/gcc/graphite-scop-detection.c b/gcc/graphite-scop-detection.c
index 57d3b4806c8..7e8d42cab0d 100644
--- a/gcc/graphite-scop-detection.c
+++ b/gcc/graphite-scop-detection.c
@@ -555,8 +555,15 @@ scop_detection::can_represent_loop (loop_p loop, sese_l scop)
   tree niter;
   struct tree_niter_desc niter_desc;
 
-  return single_exit (loop)
-    && !(loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)
+  /* We can only handle do {} while () style loops correctly.  */
+  edge exit = single_exit (loop);
+  if (!exit
+      || !single_pred_p (loop->latch)
+      || exit->src != single_pred (loop->latch)
+      || !empty_block_p (loop->latch))
+    return false;
+
+  return !(loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)
     && number_of_iterations_exit (loop, single_exit (loop), &niter_desc, false)
     && niter_desc.control.no_overflow
     && (niter = number_of_latch_executions (loop))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fa88d9d35cb..9803c91e40b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2019-01-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/86865
+	* gcc.dg/graphite/pr86865.c: New testcase.
+	* gcc.dg/graphite/pr69728.c: XFAIL.
+	* gcc.dg/graphite/scop-21.c: Likewise.
+
 2019-01-24  Martin Sebor  <msebor@redhat.com>
 
 	PR c/86125
diff --git a/gcc/testsuite/gcc.dg/graphite/pr69728.c b/gcc/testsuite/gcc.dg/graphite/pr69728.c
index e8cd7bec0a1..69e28318aaf 100644
--- a/gcc/testsuite/gcc.dg/graphite/pr69728.c
+++ b/gcc/testsuite/gcc.dg/graphite/pr69728.c
@@ -24,4 +24,6 @@ fn1 ()
    run into scheduling issues before here, not being able to handle
    empty domains.  */
 
-/* { dg-final { scan-tree-dump "loop nest optimized" "graphite" } }  */
+/* XFAILed by fix for PR86865.  */
+
+/* { dg-final { scan-tree-dump "loop nest optimized" "graphite" { xfail *-*-* } } }  */
diff --git a/gcc/testsuite/gcc.dg/graphite/pr86865.c b/gcc/testsuite/gcc.dg/graphite/pr86865.c
new file mode 100644
index 00000000000..a6b4208d830
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/graphite/pr86865.c
@@ -0,0 +1,35 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fgraphite-identity -fstack-reuse=none -fwrapv -fno-tree-ch -fno-tree-dce -fno-tree-dominator-opts -fno-tree-loop-ivcanon" } */
+
+int xy, tb;
+
+void
+bt (void)
+{
+  for (xy = 0; xy >= 0; --xy)
+    {
+      int yt[8] = { 0 };
+      int pz[2] = { 0 };
+      int sa[32] = { 0 };
+      int us;
+
+      for (us = 0; us < 8; ++us)
+	yt[us] = 0;
+
+      (void) yt;
+      (void) pz;
+      (void) sa;
+    }
+
+  tb = 1;
+}
+
+int
+main (void)
+{
+  bt ();
+  if (xy != -1)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/graphite/scop-21.c b/gcc/testsuite/gcc.dg/graphite/scop-21.c
index bd3f811d9d1..304e0792b2b 100644
--- a/gcc/testsuite/gcc.dg/graphite/scop-21.c
+++ b/gcc/testsuite/gcc.dg/graphite/scop-21.c
@@ -30,4 +30,5 @@ int test ()
 
   return a[20];
 }
-/* { dg-final { scan-tree-dump-times "number of SCoPs: 1" 1 "graphite"} } */
+/* XFAILed by the fix for PR86865.  */
+/* { dg-final { scan-tree-dump-times "number of SCoPs: 1" 1 "graphite" { xfail *-*-* } } } */