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LoongArch: implement count_{leading,trailing}_zeros

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LoongArch always support clz and ctz instructions, so we can always use
__builtin_{clz,ctz} for count_{leading,trailing}_zeros.  This improves
the code of libgcc, and also benefits Glibc once we merge longlong.h
there.

Bootstrapped and regtested on loongarch64-linux-gnu.

include/
	* longlong.h [__loongarch__] (count_leading_zeros): Define.
	[__loongarch__] (count_trailing_zeros): Likewise.
	[__loongarch__] (COUNT_LEADING_ZEROS_0): Likewise.
This commit is contained in:
Xi Ruoyao 2023-08-07 13:07:08 +02:00 committed by Alan Modra
parent 82fc3423c3
commit 079b20e89d
1 changed files with 12 additions and 0 deletions
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12
include/longlong.h
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@ -593,6 +593,18 @@ extern UDItype __umulsidi3 (USItype, USItype);
#define UMUL_TIME 14
#endif
#ifdef __loongarch__
# if W_TYPE_SIZE == 32
# define count_leading_zeros(count, x) ((count) = __builtin_clz (x))
# define count_trailing_zeros(count, x) ((count) = __builtin_ctz (x))
# define COUNT_LEADING_ZEROS_0 32
# elif W_TYPE_SIZE == 64
# define count_leading_zeros(count, x) ((count) = __builtin_clzll (x))
# define count_trailing_zeros(count, x) ((count) = __builtin_ctzll (x))
# define COUNT_LEADING_ZEROS_0 64
# endif
#endif
#if defined (__M32R__) && W_TYPE_SIZE == 32
#define add_ssaaaa(sh, sl, ah, al, bh, bl) \
/* The cmp clears the condition bit. */ \