Unverified Commit cb4ede92 authored by Xiao Wang's avatar Xiao Wang Committed by Palmer Dabbelt
Browse files

riscv: Avoid code duplication with generic bitops implementation 



There's code duplication between the fallback implementation for bitops
__ffs/__fls/ffs/fls API and the generic C implementation in
include/asm-generic/bitops/. To avoid this duplication, this patch renames
the generic C implementation by adding a "generic_" prefix to them, then we
can use these generic APIs as fallback.

Suggested-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: default avatarXiao Wang <xiao.w.wang@intel.com>
Reviewed-by: default avatarCharlie Jenkins <charlie@rivosinc.com>
Link: https://lore.kernel.org/r/20231112094421.4014931-1-xiao.w.wang@intel.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 05d450aa

arch/riscv/include/asm/bitops.h

+24 −114
Original line number Diff line number Diff line
@@ -22,6 +22,16 @@ 
#include <asm-generic/bitops/fls.h>



#else

#define __HAVE_ARCH___FFS

#define __HAVE_ARCH___FLS

#define __HAVE_ARCH_FFS

#define __HAVE_ARCH_FLS



#include <asm-generic/bitops/__ffs.h>

#include <asm-generic/bitops/__fls.h>

#include <asm-generic/bitops/ffs.h>

#include <asm-generic/bitops/fls.h>



#include <asm/alternative-macros.h>

#include <asm/hwcap.h>
@@ -37,8 +47,6 @@ 


static __always_inline unsigned long variable__ffs(unsigned long word)

{

	int num;



	asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,

				      RISCV_ISA_EXT_ZBB, 1)

			  : : : : legacy);
@@ -52,32 +60,7 @@ static __always_inline unsigned long variable__ffs(unsigned long word) 
	return word;



legacy:

	num = 0;

#if BITS_PER_LONG == 64

	if ((word & 0xffffffff) == 0) {

		num += 32;

		word >>= 32;

	}

#endif

	if ((word & 0xffff) == 0) {

		num += 16;

		word >>= 16;

	}

	if ((word & 0xff) == 0) {

		num += 8;

		word >>= 8;

	}

	if ((word & 0xf) == 0) {

		num += 4;

		word >>= 4;

	}

	if ((word & 0x3) == 0) {

		num += 2;

		word >>= 2;

	}

	if ((word & 0x1) == 0)

		num += 1;

	return num;

	return generic___ffs(word);

}



/**
@@ -93,8 +76,6 @@ static __always_inline unsigned long variable__ffs(unsigned long word) 


static __always_inline unsigned long variable__fls(unsigned long word)

{

	int num;



	asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,

				      RISCV_ISA_EXT_ZBB, 1)

			  : : : : legacy);
@@ -108,32 +89,7 @@ static __always_inline unsigned long variable__fls(unsigned long word) 
	return BITS_PER_LONG - 1 - word;



legacy:

	num = BITS_PER_LONG - 1;

#if BITS_PER_LONG == 64

	if (!(word & (~0ul << 32))) {

		num -= 32;

		word <<= 32;

	}

#endif

	if (!(word & (~0ul << (BITS_PER_LONG - 16)))) {

		num -= 16;

		word <<= 16;

	}

	if (!(word & (~0ul << (BITS_PER_LONG - 8)))) {

		num -= 8;

		word <<= 8;

	}

	if (!(word & (~0ul << (BITS_PER_LONG - 4)))) {

		num -= 4;

		word <<= 4;

	}

	if (!(word & (~0ul << (BITS_PER_LONG - 2)))) {

		num -= 2;

		word <<= 2;

	}

	if (!(word & (~0ul << (BITS_PER_LONG - 1))))

		num -= 1;

	return num;

	return generic___fls(word);

}



/**
@@ -149,46 +105,23 @@ static __always_inline unsigned long variable__fls(unsigned long word) 


static __always_inline int variable_ffs(int x)

{

	int r;



	if (!x)

		return 0;



	asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,

				      RISCV_ISA_EXT_ZBB, 1)

			  : : : : legacy);



	if (!x)

		return 0;



	asm volatile (".option push\n"

		      ".option arch,+zbb\n"

		      CTZW "%0, %1\n"

		      ".option pop\n"

		      : "=r" (r) : "r" (x) :);

		      : "=r" (x) : "r" (x) :);



	return r + 1;

	return x + 1;



legacy:

	r = 1;

	if (!(x & 0xffff)) {

		x >>= 16;

		r += 16;

	}

	if (!(x & 0xff)) {

		x >>= 8;

		r += 8;

	}

	if (!(x & 0xf)) {

		x >>= 4;

		r += 4;

	}

	if (!(x & 3)) {

		x >>= 2;

		r += 2;

	}

	if (!(x & 1)) {

		x >>= 1;

		r += 1;

	}

	return r;

	return generic_ffs(x);

}



/**
@@ -204,46 +137,23 @@ static __always_inline int variable_ffs(int x) 


static __always_inline int variable_fls(unsigned int x)

{

	int r;



	if (!x)

		return 0;



	asm_volatile_goto(ALTERNATIVE("j %l[legacy]", "nop", 0,

				      RISCV_ISA_EXT_ZBB, 1)

			  : : : : legacy);



	if (!x)

		return 0;



	asm volatile (".option push\n"

		      ".option arch,+zbb\n"

		      CLZW "%0, %1\n"

		      ".option pop\n"

		      : "=r" (r) : "r" (x) :);

		      : "=r" (x) : "r" (x) :);



	return 32 - r;

	return 32 - x;



legacy:

	r = 32;

	if (!(x & 0xffff0000u)) {

		x <<= 16;

		r -= 16;

	}

	if (!(x & 0xff000000u)) {

		x <<= 8;

		r -= 8;

	}

	if (!(x & 0xf0000000u)) {

		x <<= 4;

		r -= 4;

	}

	if (!(x & 0xc0000000u)) {

		x <<= 2;

		r -= 2;

	}

	if (!(x & 0x80000000u)) {

		x <<= 1;

		r -= 1;

	}

	return r;

	return generic_fls(x);

}



/**

include/asm-generic/bitops/__ffs.h

+6 −2
Original line number Diff line number Diff line
@@ -5,12 +5,12 @@ 
#include <asm/types.h>



/**

 * __ffs - find first bit in word.

 * generic___ffs - find first bit in word.

 * @word: The word to search

 *

 * Undefined if no bit exists, so code should check against 0 first.

 */

static __always_inline unsigned long __ffs(unsigned long word)

static __always_inline unsigned long generic___ffs(unsigned long word)

{

	int num = 0;
@@ -41,4 +41,8 @@ static __always_inline unsigned long __ffs(unsigned long word) 
	return num;

}



#ifndef __HAVE_ARCH___FFS

#define __ffs(word) generic___ffs(word)

#endif



#endif /* _ASM_GENERIC_BITOPS___FFS_H_ */

include/asm-generic/bitops/__fls.h

+6 −2
Original line number Diff line number Diff line
@@ -5,12 +5,12 @@ 
#include <asm/types.h>



/**

 * __fls - find last (most-significant) set bit in a long word

 * generic___fls - find last (most-significant) set bit in a long word

 * @word: the word to search

 *

 * Undefined if no set bit exists, so code should check against 0 first.

 */

static __always_inline unsigned long __fls(unsigned long word)

static __always_inline unsigned long generic___fls(unsigned long word)

{

	int num = BITS_PER_LONG - 1;
@@ -41,4 +41,8 @@ static __always_inline unsigned long __fls(unsigned long word) 
	return num;

}



#ifndef __HAVE_ARCH___FLS

#define __fls(word) generic___fls(word)

#endif



#endif /* _ASM_GENERIC_BITOPS___FLS_H_ */

include/asm-generic/bitops/ffs.h

+6 −2
Original line number Diff line number Diff line
@@ -3,14 +3,14 @@ 
#define _ASM_GENERIC_BITOPS_FFS_H_



/**

 * ffs - find first bit set

 * generic_ffs - find first bit set

 * @x: the word to search

 *

 * This is defined the same way as

 * the libc and compiler builtin ffs routines, therefore

 * differs in spirit from ffz (man ffs).

 */

static inline int ffs(int x)

static inline int generic_ffs(int x)

{

	int r = 1;
@@ -39,4 +39,8 @@ static inline int ffs(int x) 
	return r;

}



#ifndef __HAVE_ARCH_FFS

#define ffs(x) generic_ffs(x)

#endif



#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */

include/asm-generic/bitops/fls.h

+6 −2
Original line number Diff line number Diff line
@@ -3,14 +3,14 @@ 
#define _ASM_GENERIC_BITOPS_FLS_H_



/**

 * fls - find last (most-significant) bit set

 * generic_fls - find last (most-significant) bit set

 * @x: the word to search

 *

 * This is defined the same way as ffs.

 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.

 */



static __always_inline int fls(unsigned int x)

static __always_inline int generic_fls(unsigned int x)

{

	int r = 32;
@@ -39,4 +39,8 @@ static __always_inline int fls(unsigned int x) 
	return r;

}



#ifndef __HAVE_ARCH_FLS

#define fls(x) generic_fls(x)

#endif



#endif /* _ASM_GENERIC_BITOPS_FLS_H_ */