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lower-bitint: Fix up handle_operand_addr INTEGER_CST handling [PR113361]

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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.

2024-01-13  Jakub Jelinek  <jakub@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.
This commit is contained in:
Jakub Jelinek 2024-01-13 11:29:15 +01:00
parent 7012a25252
commit f77a87982d
2 changed files with 43 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

18
gcc/gimple-lower-bitint.cc
View file

@ -2227,7 +2227,9 @@ bitint_large_huge::handle_operand_addr (tree op, gimple *stmt,
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 (tree op, gimple *stmt,
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)
{

31
gcc/testsuite/gcc.dg/torture/bitint-47.c Normal file
View file

@ -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;
}