From: Jakub Jelinek <jakub@redhat.com>
Date: Sat, 15 Feb 2020 11:53:44 +0000 (+0100)
Subject: match.pd: Disallow side-effects in GENERIC for non-COND_EXPR to COND_EXPR simplificat... 
X-Git-Tag: releases/gcc-9.3.0~120
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=498055331393d3c32fea5a6142c926b6a7700b8d;p=thirdparty%2Fgcc.git

match.pd: Disallow side-effects in GENERIC for non-COND_EXPR to COND_EXPR simplifications [PR93744]

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 1e97432f0d58..7294b6880285 100644
--- 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 bd3e3bf1ae90..f7e192d9b734 100644
--- 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 ee3fee8f4e91..db43b90f3b42 100644
--- 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
index 000000000000..3229c9b2bd67
--- /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
index 000000000000..0c1baaac77b3
--- /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
index 000000000000..8542c7c53ba0
--- /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;
+}