tree-optimization/92335 - Improve sinking heuristics for vectorization

The following delays sinking of loads within the same innermost
loop when it was unconditional before.  That's a not uncommon
issue preventing vectorization when masked loads are not available.

	PR tree-optimization/92335
	* tree-ssa-sink.cc (select_best_block): Before loop
	optimizations avoid sinking unconditional loads/stores
	in innermost loops to conditional executed places.

	* gcc.dg/tree-ssa/ssa-sink-10.c: Disable vectorizing.
	* gcc.dg/tree-ssa/predcom-9.c: Clone from ssa-sink-10.c,
	expect predictive commoning to happen instead of sinking.
	* gcc.dg/vect/pr65947-3.c: Ajdust.

4 files changed, 34 insertions, 6 deletions

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/predcom-9.c b/gcc/testsuite/gcc.dg/tree-ssa/predcom-9.c
new file mode 100644
index 0000000..b0fb0e2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/predcom-9.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-sink-details -fdump-tree-pcom-details" } */
+
+int x[1024], y[1024], z[1024], w[1024];
+void foo (void)
+{
+  int i;
+  for (i = 1; i < 1024; ++i)
+    {
+      int a = x[i];
+      int b = y[i];
+      int c = x[i-1];
+      int d = y[i-1];
+      if (w[i])
+	z[i] = (a + b) + (c + d);
+    }
+}
+
+/* { dg-final { scan-tree-dump-not "Sinking # VUSE" "sink1" } } */
+/* { dg-final { scan-tree-dump "Executing predictive commoning without unrolling" "pcom" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
index 535cb32..a35014b 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-sink-10.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-sink-details -fno-tree-pre" } */
+/* { dg-options "-O2 -fdump-tree-sink-details -fno-tree-vectorize -fno-tree-pre" } */
 
 int x[1024], y[1024], z[1024], w[1024];
 void foo (void)
diff --git a/gcc/testsuite/gcc.dg/vect/pr65947-3.c b/gcc/testsuite/gcc.dg/vect/pr65947-3.c
index f1bfad6..6b4077e 100644
--- a/gcc/testsuite/gcc.dg/vect/pr65947-3.c
+++ b/gcc/testsuite/gcc.dg/vect/pr65947-3.c
@@ -51,10 +51,6 @@ main (void)
   return 0;
 }
 
-/* Since the fix for PR97307 which sinks the load of a[i], preventing
-   if-conversion to happen, targets that cannot do masked loads only
-   vectorize the inline copy.  */
-/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 2 "vect" { target vect_masked_load } } } */
-/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 1 "vect" { target { ! vect_masked_load } } } } */
+/* { dg-final { scan-tree-dump-times "LOOP VECTORIZED" 2 "vect" } } */
 /* { dg-final { scan-tree-dump-times "optimizing condition reduction with FOLD_EXTRACT_LAST" 2 "vect" { target vect_fold_extract_last } } } */
 /* { dg-final { scan-tree-dump-not "condition expression based on integer induction." "vect" } } */
diff --git a/gcc/tree-ssa-sink.cc b/gcc/tree-ssa-sink.cc
index cf0a32a..d83d7be 100644
--- a/gcc/tree-ssa-sink.cc
+++ b/gcc/tree-ssa-sink.cc
@@ -220,6 +220,18 @@ select_best_block (basic_block early_bb,
   if (bb_loop_depth (best_bb) < bb_loop_depth (early_bb))
     return best_bb;
 
+  /* Avoid turning an unconditional read into a conditional one when we
+     still might want to perform vectorization.  */
+  if (best_bb->loop_father == early_bb->loop_father
+      && loop_outer (best_bb->loop_father)
+      && !best_bb->loop_father->inner
+      && gimple_vuse (stmt)
+      && flag_tree_loop_vectorize
+      && !(cfun->curr_properties & PROP_loop_opts_done)
+      && dominated_by_p (CDI_DOMINATORS, best_bb->loop_father->latch, early_bb)
+      && !dominated_by_p (CDI_DOMINATORS, best_bb->loop_father->latch, best_bb))
+    return early_bb;
+
   /* Get the sinking threshold.  If the statement to be moved has memory
      operands, then increase the threshold by 7% as those are even more
      profitable to avoid, clamping at 100%.  */