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.

6 files changed, 77 insertions, 3 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 22f990a..3ef5b4d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+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.
+
 2020-02-15  David Malcolm  <dmalcolm@redhat.com>
 	    Bernd Edlinger  <bernd.edlinger@hotmail.de>
 
diff --git a/gcc/match.pd b/gcc/match.pd
index 73834c2..19df0c4 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1472,7 +1472,8 @@ 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.  */
@@ -2709,7 +2710,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && TREE_CODE (TREE_TYPE (@4)) != BOOLEAN_TYPE
        && INTEGRAL_TYPE_P (TREE_TYPE (@5))
        && (TYPE_PRECISION (TREE_TYPE (@4)) >= TYPE_PRECISION (type)
-	   || !TYPE_UNSIGNED (TREE_TYPE (@4))))
+	   || !TYPE_UNSIGNED (TREE_TYPE (@4)))
+       && (GIMPLE || !TREE_SIDE_EFFECTS (@1)))
    (cond (cmp @2 @3) @1 @0)))
  (simplify
   (plus:c @0 (bit_and:c (minus @1 @0)
@@ -2719,7 +2721,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && TREE_CODE (TREE_TYPE (@4)) != BOOLEAN_TYPE
        && INTEGRAL_TYPE_P (TREE_TYPE (@5))
        && (TYPE_PRECISION (TREE_TYPE (@4)) >= TYPE_PRECISION (type)
-	   || !TYPE_UNSIGNED (TREE_TYPE (@4))))
+	   || !TYPE_UNSIGNED (TREE_TYPE (@4)))
+       && (GIMPLE || !TREE_SIDE_EFFECTS (@1)))
    (cond (cmp @2 @3) @1 @0))))
 
 /* Simplifications of shift and rotates.  */
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3059e23..77c781a 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 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
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
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;
+}