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AVR: target/114981 - Support __builtin_powi[l] / __powidf2.

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This supports __powidf2 by means of a double wrapper for already
existing f7_powi (renamed to __f7_powi by f7-renames.h).
It tweaks the implementation so that it does not perform trivial
multiplications with 1.0 any more, but instead uses a move.
It also fixes the last statement of f7_powi, which was wrong.
Notice that f7_powi was unused until now.

	PR target/114981
libgcc/config/avr/libf7/
	* libf7-common.mk (F7_ASM_PARTS): Add D_powi
	* libf7-asm.sx (F7MOD_D_powi_, __powidf2): New module and function.
	* libf7.c (f7_powi): Fix last (wrong) statement.
	Tweak trivial multiplications with 1.0.

gcc/testsuite/
	* gcc.target/avr/pr114981-powil.c: New test.
This commit is contained in:
Georg-Johann Lay 2024-05-08 17:56:05 +02:00
parent 2f00e6caca
commit de4eea7d7e
4 changed files with 68 additions and 8 deletions
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33
gcc/testsuite/gcc.target/avr/pr114981-powil.c Normal file
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@ -0,0 +1,33 @@
/* { dg-do run { target { ! avr_tiny } } } */
/* { dg-additional-options "-Os" } */
const long double vals[] =
{
0.0625L, -0.125L, 0.25L, -0.5L,
1.0L,
-2.0L, 4.0L, -8.0L, 16.0L
};
#define ARRAY_SIZE(X) ((int) (sizeof(X) / sizeof(*X)))
__attribute__((noinline,noclone))
void test1 (long double x)
{
int i;
for (i = 0; i < ARRAY_SIZE (vals); ++i)
{
long double val0 = vals[i];
long double val1 = __builtin_powil (x, i - 4);
__asm ("" : "+r" (val0));
if (val0 != val1)
__builtin_exit (__LINE__);
}
}
int main (void)
{
test1 (-2.0L);
return 0;
}

12
libgcc/config/avr/libf7/libf7-asm.sx
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@ -1877,4 +1877,16 @@ ENDF call_ddd
#include "f7-wraps.h"
;;; Some additional, singular wraps that don't match any pattern.
;; double __powidf2 (double, int) ; __builtin_powi
#ifdef F7MOD_D_powi_
_DEFUN __powidf2
.global F7_NAME(powi)
ldi ZH, hi8(gs(F7_NAME(powi)))
ldi ZL, lo8(gs(F7_NAME(powi)))
F7jmp call_ddx
_ENDF __powidf2
#endif /* F7MOD_D_powi_ */
#endif /* !AVR_TINY */

2
libgcc/config/avr/libf7/libf7-common.mk
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@ -22,7 +22,7 @@ F7_ASM_PARTS += addsub_mant_scaled store load
F7_ASM_PARTS += to_integer to_unsigned clz normalize_with_carry normalize
F7_ASM_PARTS += store_expo sqrt16 sqrt_approx div
F7_ASM_PARTS += D_class D_fma
F7_ASM_PARTS += D_class D_fma D_powi
F7_ASM_PARTS += D_isnan D_isinf D_isfinite D_signbit D_copysign D_neg D_fabs
F7_ASM_PARTS += call_dd call_ddd

25
libgcc/config/avr/libf7/libf7.c
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@ -1752,20 +1752,33 @@ void f7_powi (f7_t *cc, const f7_t *aa, int ii)
{
uint16_t u16 = ii;
f7_t xx27, *xx2 = &xx27;
bool cc_is_one = true;
bool expo_is_neg = false;
if (ii < 0)
{
u16 = -u16;
expo_is_neg = true;
}
f7_copy (xx2, aa);
f7_set_u16 (cc, 1);
while (1)
{
if (u16 & 1)
{
if (cc_is_one)
{
// C *= X2 simplifies to C = X2.
f7_copy (cc, xx2);
cc_is_one = false;
}
else
f7_Imul (cc, xx2);
}
if (! f7_is_nonzero (cc))
if (! cc_is_one
&& ! f7_is_nonzero (cc))
break;
u16 >>= 1;
@ -1774,8 +1787,10 @@ void f7_powi (f7_t *cc, const f7_t *aa, int ii)
f7_Isquare (xx2);
}
if (ii < 0)
f7_div1 (xx2, aa);
if (cc_is_one)
f7_set_u16 (cc, 1);
else if (expo_is_neg)
f7_div1 (cc, cc);
}
#endif // F7MOD_powi_