Hi!
As the testcase shows, the INTEGER_CST handling in handle_operand_addr
(i.e. what is used when passing address of an integer to a bitint library
routine) wasn't correct. If the minimum precision to represent an
INTEGER_CST is smaller or equal to limb_prec, the code correctly uses
m_limb_type; if the minimum precision of a _BitInt INTEGER_CST is large
enough such that the bitint is middle, large or huge, everything is fine
too. But the code wasn't handling correctly e.g. __int128 constants which
need more than limb_prec bits or _BitInt constants which on the architecture
are considered small (say have DImode limb_mode, TImode abi_limb_mode and
for [65, 128] bits use TImode scalar like the proposed aarch64 patch).
Best would be to use an array of 2/3/4 limbs in that case, but we'd need to
convert the INTEGER_CST to a CONSTRUCTOR in the right endianity etc.,
so the code was using mid_min_prec to enforce a middle _BitInt precision.
Except that mid_min_prec can be 0 and not computed yet, or it doesn't have
to be the smallest middle _BitInt precision, just the smallest so far
encountered. So, on the testcase one possibility was that it used precision
65 from mid_min_prec, even when the INTEGER_CST actually needed larger
minimum precision (96 bits at least), or crashed when mid_min_prec was 0.
The patch fixes it in 2 hunks, the first makes sure we actually try to
create a BITINT_TYPE for the > limb_prec cases like __int128, and the second
instead of using mid_min_prec attempts to increase mp precision until it
isn't small anymore.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2024-01-13 Jakub Jelinek <ja...@redhat.com>
PR tree-optimization/113361
* gimple-lower-bitint.cc (bitint_large_huge::handle_operand_addr):
Fix up determination of the type for > limb_prec constants.
* gcc.dg/torture/bitint-47.c: New test.
--- gcc/gimple-lower-bitint.cc.jj 2024-01-12 11:23:12.000000000 +0100
+++ gcc/gimple-lower-bitint.cc 2024-01-13 00:18:19.255889866 +0100
@@ -2227,7 +2227,9 @@ bitint_large_huge::handle_operand_addr (
mp = CEIL (min_prec, limb_prec) * limb_prec;
if (mp == 0)
mp = 1;
- if (mp >= (unsigned) TYPE_PRECISION (TREE_TYPE (op)))
+ if (mp >= (unsigned) TYPE_PRECISION (TREE_TYPE (op))
+ && (TREE_CODE (TREE_TYPE (op)) == BITINT_TYPE
+ || TYPE_PRECISION (TREE_TYPE (op)) <= limb_prec))
type = TREE_TYPE (op);
else
type = build_bitint_type (mp, 1);
@@ -2237,11 +2239,15 @@ bitint_large_huge::handle_operand_addr (
if (TYPE_PRECISION (type) <= limb_prec)
type = m_limb_type;
else
- /* This case is for targets which e.g. have 64-bit
- limb but categorize up to 128-bits _BitInts as
- small. We could use type of m_limb_type[2] and
- similar instead to save space. */
- type = build_bitint_type (mid_min_prec, 1);
+ {
+ while (bitint_precision_kind (mp) == bitint_prec_small)
+ mp += limb_prec;
+ /* This case is for targets which e.g. have 64-bit
+ limb but categorize up to 128-bits _BitInts as
+ small. We could use type of m_limb_type[2] and
+ similar instead to save space. */
+ type = build_bitint_type (mp, 1);
+ }
}
if (prec_stored)
{
--- gcc/testsuite/gcc.dg/torture/bitint-47.c.jj 2024-01-13 00:23:40.627562314
+0100
+++ gcc/testsuite/gcc.dg/torture/bitint-47.c 2024-01-13 00:25:35.571025508
+0100
@@ -0,0 +1,31 @@
+/* PR tree-optimization/113361 */
+/* { dg-do run { target { bitint && int128 } } } */
+/* { dg-options "-std=gnu23" } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "*" } { "-O0" "-O2" } } */
+/* { dg-skip-if "" { ! run_expensive_tests } { "-flto" } { "" } } */
+
+#if __BITINT_MAXWIDTH__ >= 129
+int
+foo (_BitInt(65) x)
+{
+ return __builtin_mul_overflow_p ((__int128) 0xffffffff << 64, x,
(_BitInt(129)) 0);
+}
+
+int
+bar (_BitInt(63) x)
+{
+ return __builtin_mul_overflow_p ((__int128) 0xffffffff << 64, x,
(_BitInt(129)) 0);
+}
+#endif
+
+int
+main ()
+{
+#if __BITINT_MAXWIDTH__ >= 129
+ if (!foo (5167856845))
+ __builtin_abort ();
+ if (!bar (5167856845))
+ __builtin_abort ();
+#endif
+ return 0;
+}
Jakub
