[PATCH] tree-optimization/110269 - restore missed condition folding

[PATCH] tree-optimization/110269 - restore missed condition folding

[Richard Biener]

The following makes sure we optimize x != 0 using range info
via tree_expr_nonzero_p via match.pd.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

This causes

FAIL: gcc.dg/tree-ssa/pr103257-1.c scan-tree-dump-times optimized 
"link_error" 0

because we now improve early folding the following way

-  if (a ((unsigned int) ((0, 1) && b != 0) > b, (int) (short int) c) != 
0)
+  if (a ((unsigned int) (b != 0) > b, (int) (short int) c) != 0)

and that causes some initial CFG turned into straight-line code
which we not handle as expected.  I'm going to file a bug
for this but go ahead pushing this patch.

Richard.


	PR tree-optimization/110269
	* fold-const.cc (fold_binary_loc): Merge x != 0 folding
	with tree_expr_nonzero_p ...
	* match.pd (cmp (convert? addr@0) integer_zerop): With this
	pattern.

	* gcc.dg/tree-ssa/pr110269.c: New testcase.
---
 gcc/fold-const.cc                        |  7 -----
 gcc/match.pd                             |  4 +--
 gcc/testsuite/gcc.dg/tree-ssa/pr110269.c | 34 ++++++++++++++++++++++++
 3 files changed, 36 insertions(+), 9 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110269.c

diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index 34c5f192a1d..7589498dbd0 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -12298,13 +12298,6 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type,
 			      tem, build_int_cst (TREE_TYPE (tem), 0));
 	}
 
-      if (integer_zerop (arg1)
-	  && tree_expr_nonzero_p (arg0))
-        {
-	  tree res = constant_boolean_node (code==NE_EXPR, type);
-	  return omit_one_operand_loc (loc, type, res, arg0);
-	}
-
       if (TREE_CODE (arg0) == BIT_XOR_EXPR
 	  && TREE_CODE (arg1) == BIT_XOR_EXPR)
 	{
diff --git a/gcc/match.pd b/gcc/match.pd
index 0fcf91f0eeb..264f9cb8a40 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6120,8 +6120,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
    (cmp @0 (bit_xor @1 (convert @2)))))
 
  (simplify
-  (cmp (convert? addr@0) integer_zerop)
-  (if (tree_single_nonzero_warnv_p (@0, NULL))
+  (cmp (nop_convert? @0) integer_zerop)
+  (if (tree_expr_nonzero_p (@0))
    { constant_boolean_node (cmp == NE_EXPR, type); }))
 
  /* (X & C) op (Y & C) into (X ^ Y) & C op 0.  */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110269.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110269.c
new file mode 100644
index 00000000000..c68a6f91604
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110269.c
@@ -0,0 +1,34 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-ccp2 -fdump-tree-optimized" } */
+
+void foo(void);
+static int a = 1, c;
+static int *b = &a;
+static int **d = &b;
+static int ***e = &d;
+void __assert_fail() __attribute__((__noreturn__));
+static int f() {
+    if (a) return a;
+    for (; c;) *e = 0;
+    if (b) __assert_fail();
+    return 6;
+}
+int main() {
+    if (f()) {
+        *d = 0;
+        if (b == 0)
+            ;
+        else {
+            __builtin_unreachable();
+            __assert_fail();
+        }
+    }
+    if (b == 0)
+        ;
+    else
+        foo();
+    ;
+}
+
+/* { dg-final { scan-tree-dump-times "Folding predicate" 2 "ccp2" } } */
+/* { dg-final { scan-tree-dump-not "foo" "optimized" } } */
-- 
2.35.3