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builtins: Fix fold_builtin_query clzg/ctzg side-effects handling [PR112639]

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As the testcase shows, I've missed one spot where initially the code thinks
it could use 2 argument IFN_CLZ/IFN_CTZ form, but then verifies it can't
because it doesn't have the right target value and turns it into the
arg0 ? arg1 : .C[LT]Z (arg0)
form.  That form evaluates the argument twice though and so needs save_expr,
which I've missed to call in that case.  In other cases where it is known
from the beginning that it will be needed (e.g. the __builtin_clzg case
on types smaller than unsigned int where we'll need to add an addend
to the clz value) or the unsigned __int128 expansion called save_expr
before.

2023-11-21  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/112639
	* builtins.cc (fold_builtin_bit_query): If arg0 has side-effects, arg1
	is specified but cleared, call save_expr on arg0.

	* gcc.dg/torture/pr112639.c: New test.
This commit is contained in:
Jakub Jelinek 2023-11-21 09:32:37 +01:00
parent 7ad308bd4c
commit 8a8a6d60c6
2 changed files with 36 additions and 0 deletions
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2
gcc/builtins.cc
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@ -9819,6 +9819,8 @@ fold_builtin_bit_query (location_t loc, enum built_in_function fcode,
if (!direct_internal_fn_supported_p (ifn, arg0_type,
OPTIMIZE_FOR_BOTH))
arg2 = NULL_TREE;
if (arg2 == NULL_TREE)
arg0 = save_expr (arg0);
}
if (fcodei == END_BUILTINS || arg2)
call = build_call_expr_internal_loc (loc, ifn, integer_type_node,

34
gcc/testsuite/gcc.dg/torture/pr112639.c Normal file
View file

@ -0,0 +1,34 @@
/* PR middle-end/112639 */
/* { dg-do run } */
unsigned long long b = 0;
int
foo (void)
{
return __builtin_clzg (b++, __SIZEOF_LONG_LONG__ * __CHAR_BIT__);
}
int
bar (void)
{
return __builtin_ctzg (b++, __SIZEOF_LONG_LONG__ * __CHAR_BIT__);
}
int
main ()
{
if (foo () != __SIZEOF_LONG_LONG__ * __CHAR_BIT__ || b != 1)
__builtin_abort ();
if (foo () != __SIZEOF_LONG_LONG__ * __CHAR_BIT__ - 1 || b != 2)
__builtin_abort ();
if (foo () != __SIZEOF_LONG_LONG__ * __CHAR_BIT__ - 2 || b != 3)
__builtin_abort ();
b = 0;
if (bar () != __SIZEOF_LONG_LONG__ * __CHAR_BIT__ || b != 1)
__builtin_abort ();
if (bar () != 0 || b != 2)
__builtin_abort ();
if (bar () != 1 || b != 3)
__builtin_abort ();
}