Fix merging of 2 predictors (PR tree-optimization/86925).

2018-08-15  Martin Liska  <mliska@suse.cz>

        PR tree-optimization/86925
	* predict.c (expr_expected_value_1): When taking
        later predictor, assign also probability.
        Use fold_build2_initializer_loc in order to fold
        the expression in -frounding-math.
2018-08-15  Martin Liska  <mliska@suse.cz>

        PR tree-optimization/86925
	* gcc.dg/predict-20.c: New test.
	* gcc.dg/predict-21.c: New test.

From-SVN: r263552

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9dc9acd84c0307d5794a952245975feee201a46f..40c7be5470a426d48f7fecee9a34631694fe1f36 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2018-08-15  Martin Liska  <mliska@suse.cz>
+
+        PR tree-optimization/86925
+       * predict.c (expr_expected_value_1): When taking
+        later predictor, assign also probability.
+        Use fold_build2_initializer_loc in order to fold
+        the expression in -frounding-math.
+
 2018-08-14 Allan Sandfeld Jensen <allan.jensen@qt.io>
 
        * config/i386/i386.c (expand_vec_perm_movs): New method matching movs

diff --git a/gcc/predict.c b/gcc/predict.c
index 3fbe3b704b318f46c8b65add32d19dc478795b7a..8c8e79153fc00f2708a72f462454622a3c9ce790 100644 (file)
--- a/gcc/predict.c
+++ b/gcc/predict.c
@@ -2332,13 +2332,17 @@ expr_expected_value_1 (tree type, tree op0, enum tree_code code,
              if (arg == PHI_RESULT (def))
                continue;
 
+             HOST_WIDE_INT probability2;
              new_val = expr_expected_value (arg, visited, &predictor2,
-                                            probability);
+                                            &probability2);
 
              /* It is difficult to combine value predictors.  Simply assume
                 that later predictor is weaker and take its prediction.  */
              if (*predictor < predictor2)
-               *predictor = predictor2;
+               {
+                 *predictor = predictor2;
+                 *probability = probability2;
+               }
              if (!new_val)
                return NULL;
              if (!val)
@@ -2423,7 +2427,8 @@ expr_expected_value_1 (tree type, tree op0, enum tree_code code,
                  tree base = build_int_cst (integer_type_node,
                                             REG_BR_PROB_BASE);
                  base = build_real_from_int_cst (t, base);
-                 tree r = fold_build2 (MULT_EXPR, t, prob, base);
+                 tree r = fold_build2_initializer_loc (UNKNOWN_LOCATION,
+                                                       MULT_EXPR, t, prob, base);
                  HOST_WIDE_INT probi
                    = real_to_integer (TREE_REAL_CST_PTR (r));
                  if (probi >= 0 && probi <= REG_BR_PROB_BASE)

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 18cae4dc6f834a4a40b6b8bd2b26acfa7e6abdac..46a16279fe055318036e8945ae1ba39b1bb5c6bc 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2018-08-15  Martin Liska  <mliska@suse.cz>
+
+        PR tree-optimization/86925
+       * gcc.dg/predict-20.c: New test.
+       * gcc.dg/predict-21.c: New test.
+
 2018-08-15  Paolo Carlini  <paolo.carlini@oracle.com>
 
        * g++.dg/init/goto3.C: Adjust for error instead of permerror.

diff --git a/gcc/testsuite/gcc.dg/predict-20.c b/gcc/testsuite/gcc.dg/predict-20.c
new file mode 100644 (file)
index 0000000..31d0183
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/predict-20.c
@@ -0,0 +1,23 @@
+/* PR tree-optimization/86925 */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-profile_estimate" } */
+
+int a, b;
+
+void
+c ()
+{
+  for (;;)
+    {
+      if (__builtin_expect (b < 0, 0))
+       break;
+      if (__builtin_expect (a, 1))
+       break;
+    }
+  int d = b < 0;
+  if (__builtin_expect (d, 0))
+    asm("");
+}
+
+/* { dg-final { scan-tree-dump-times "__builtin_expect heuristics of edge" 3 "profile_estimate"} } */

diff --git a/gcc/testsuite/gcc.dg/predict-21.c b/gcc/testsuite/gcc.dg/predict-21.c
new file mode 100644 (file)
index 0000000..5949e5f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/predict-21.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-profile_estimate -frounding-math" } */
+
+extern int global;
+
+void foo (int base)
+{
+  for (int i = 0; __builtin_expect_with_probability (i < base, 1, 0.05f); i++)
+    global++;
+}
+
+/* { dg-final { scan-tree-dump "first match heuristics: 5.00%" "profile_estimate"} } */
+/* { dg-final { scan-tree-dump "__builtin_expect_with_probability heuristics of edge .*->.*: 5.00%" "profile_estimate"} } */