range-op: Fix up ABSU_EXPR handling [PR113756]

ABSU_EXPR unary expr is special because it has a signed integer
argument and unsigned integer result (of the same precision).

The following testcase is miscompiled since ABSU_EXPR handling has
been added to range-op because it uses widest_int::from with the
result sign (i.e. UNSIGNED) rather than the operand sign (i.e. SIGNED),
so e.g. for the 32-bit int argument mask ends up 0xffffffc1 or something
similar and even when it has most significant bit in the precision set,
in widest_int (tree-ssa-ccp.cc really should stop using widest_int, but
that is I think stage1 task) it doesn't appear to be negative and so
bit_value_unop ABSU_EXPR doesn't set the resulting mask/value from
oring of the argument and its negation.

Fixed thusly, not doing that for GIMPLE_BINARY_RHS because I don't know
about a binary op that would need something similar.

2024-02-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/113756
	* range-op.cc (update_known_bitmask): For GIMPLE_UNARY_RHS,
	use TYPE_SIGN (lh.type ()) instead of sign for widest_int::from
	of lh_bits value and mask.

	* gcc.dg/pr113756.c: New test.

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 9a1a3c8bcdbb65b3b794df5f455c00bb39d27533..4ccb86ef0ba89b907c5b45f7a8ea5c8147edb963 100644 (file)
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -435,8 +435,10 @@ update_known_bitmask (irange &r, tree_code code,
       bit_value_unop (code, sign, prec, &widest_value, &widest_mask,
                      TYPE_SIGN (lh.type ()),
                      TYPE_PRECISION (lh.type ()),
-                     widest_int::from (lh_bits.value (), sign),
-                     widest_int::from (lh_bits.mask (), sign));
+                     widest_int::from (lh_bits.value (),
+                                       TYPE_SIGN (lh.type ())),
+                     widest_int::from (lh_bits.mask (),
+                                       TYPE_SIGN (lh.type ())));
       break;
     case GIMPLE_BINARY_RHS:
       bit_value_binop (code, sign, prec, &widest_value, &widest_mask,

diff --git a/gcc/testsuite/gcc.dg/pr113756.c b/gcc/testsuite/gcc.dg/pr113756.c
new file mode 100644 (file)
index 0000000..1444220
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr113756.c
@@ -0,0 +1,36 @@
+/* PR tree-optimization/113756 */
+/* { dg-do run { target int32plus } } */
+/* { dg-options "-O2" } */
+
+int d, e, i, k, l = -8;
+signed char h, j;
+
+int
+bar (int n, int o, int p3)
+{
+  int a = o - p3, b = n - p3, c = a + b, f = -b, g = c < 0 ? -c : c;
+  return a <= f && a <= g ? o : p3;
+}
+
+void
+foo (int *n, unsigned short o)
+{
+  unsigned p = 8896;
+  for (; e >= 0; e--)
+    p = 5377;
+  for (; h <= 0; h++)
+    for (; j <= 0; j++)
+      {
+       *n = 1611581749;
+       i = bar (34, p - 5294, *n - 1611581687);
+       k = i + p + 65535 + o + *n - 1611718251;
+       if (k != 0)
+         __builtin_abort ();
+      }
+}
+
+int
+main ()
+{
+  foo (&l, l);
+}