match.pd: Disallow side-effects in GENERIC for non-COND_EXPR to COND_EXPR simplificat...

As the following testcases show (the first one reported, last two
found by code inspection), we need to disallow side-effects
in simplifications that turn some unconditional expression into conditional
one.  From my little understanding of genmatch.c, it is able to
automatically disallow side effects if the same operand is used multiple
times in the match pattern, maybe if it is used multiple times in the
replacement pattern, and if it is used in conditional contexts in the match
pattern, could it be taught to handle this case too?  If yes, perhaps
just the first hunk could be usable for 8/9 backports (+ the testcases).

2020-02-15  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/93744
	* match.pd (((m1 >/</>=/<= m2) * d -> (m1 >/</>=/<= m2) ? d : 0,
	A - ((A - B) & -(C cmp D)) -> (C cmp D) ? B : A,
	A + ((B - A) & -(C cmp D)) -> (C cmp D) ? B : A): For GENERIC, make
	sure @2 in the first and @1 in the other patterns has no side-effects.

	* gcc.c-torture/execute/pr93744-1.c: New test.
	* gcc.c-torture/execute/pr93744-2.c: New test.
	* gcc.c-torture/execute/pr93744-3.c: New test.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1e97432f0d58c123e452c0a33495d020b61845b1..7294b688028578f3bbe835ff91e16bb1d04812d6 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2020-02-15  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93744
+       * match.pd (((m1 >/</>=/<= m2) * d -> (m1 >/</>=/<= m2) ? d : 0): For
+       GENERIC, make sure @2 in the first and @1 in the other patterns has no
+       side-effects.
+
 2020-02-14  Eric Botcazou  <ebotcazou@adacore.com>
 
        PR target/93704

diff --git a/gcc/match.pd b/gcc/match.pd
index bd3e3bf1ae90f57b8f5c2b9b5125ac84946403c4..f7e192d9b7348c59f55b08059584dbd6f0ac2aba 100644 (file)
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1419,7 +1419,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 (for cmp (gt lt ge le)
 (simplify
  (mult (convert (cmp @0 @1)) @2)
-  (cond (cmp @0 @1) @2 { build_zero_cst (type); })))
+  (if (GIMPLE || !TREE_SIDE_EFFECTS (@2))
+   (cond (cmp @0 @1) @2 { build_zero_cst (type); }))))
 
 /* For integral types with undefined overflow and C != 0 fold
    x * C EQ/NE y * C into x EQ/NE y.  */

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ee3fee8f4e91053b2da5857a861b805cdf7ace37..db43b90f3b4285e6b823a51d26499ffa61063762 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,10 @@
+2020-02-15  Jakub Jelinek  <jakub@redhat.com>
+
+       PR tree-optimization/93744
+       * gcc.c-torture/execute/pr93744-1.c: New test.
+       * gcc.c-torture/execute/pr93744-2.c: New test.
+       * gcc.c-torture/execute/pr93744-3.c: New test.
+
 2020-02-14  Jakub Jelinek  <jakub@redhat.com>
 
        PR c++/61414

diff --git a/gcc/testsuite/gcc.c-torture/execute/pr93744-1.c b/gcc/testsuite/gcc.c-torture/execute/pr93744-1.c
new file mode 100644 (file)
index 0000000..3229c9b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr93744-1.c
@@ -0,0 +1,14 @@
+/* PR tree-optimization/93744 */
+
+typedef int I;
+
+int
+main ()
+{
+  int a = 0;
+  I b = 0;
+  (a > 0) * (b |= 2);
+  if (b != 2)
+    __builtin_abort ();
+  return 0;
+}

diff --git a/gcc/testsuite/gcc.c-torture/execute/pr93744-2.c b/gcc/testsuite/gcc.c-torture/execute/pr93744-2.c
new file mode 100644 (file)
index 0000000..0c1baaa
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr93744-2.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/93744 */
+
+int w;
+
+int
+foo (int x, int y, int z)
+{
+  int r = z - ((z - w++) & -(x < y));
+  return r;
+}
+
+int
+main ()
+{
+  w = 4;
+  if (foo (5, 7, 12) != 4 || w != 5)
+    __builtin_abort ();
+  if (foo (7, 5, 12) != 12 || w != 6)
+    __builtin_abort ();
+  return 0;
+}

diff --git a/gcc/testsuite/gcc.c-torture/execute/pr93744-3.c b/gcc/testsuite/gcc.c-torture/execute/pr93744-3.c
new file mode 100644 (file)
index 0000000..8542c7c
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr93744-3.c
@@ -0,0 +1,21 @@
+/* PR tree-optimization/93744 */
+
+int w;
+
+int
+foo (int x, int y, int z)
+{
+  int r = z + ((w++ - z) & -(x < y));
+  return r;
+}
+
+int
+main ()
+{
+  w = 4;
+  if (foo (5, 7, 12) != 4 || w != 5)
+    __builtin_abort ();
+  if (foo (7, 5, 12) != 12 || w != 6)
+    __builtin_abort ();
+  return 0;
+}