Hi!
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.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-02-06 Jakub Jelinek <ja...@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.
--- gcc/range-op.cc.jj 2024-01-03 11:51:28.199777434 +0100
+++ gcc/range-op.cc 2024-02-06 16:51:55.549127825 +0100
@@ -435,8 +435,10 @@ update_known_bitmask (irange &r, tree_co
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,
--- gcc/testsuite/gcc.dg/pr113756.c.jj 2024-02-06 17:00:52.835679796 +0100
+++ gcc/testsuite/gcc.dg/pr113756.c 2024-02-06 17:00:31.159980326 +0100
@@ -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);
+}
Jakub
