Commit f46ccdb8 authored by Heiko Carstens's avatar Heiko Carstens Committed by Alexander Gordeev
Browse files

s390/bitops: Cleanup __flogr() 



The flogr() inline assembly has no side effects and generates the same
output if the input does not change. Therefore remove the volatile
qualifier to allow the compiler to optimize the inline assembly away,
if possible.

Also remove the superfluous '\n' which makes the inline assembly appear
larger than it is according to compiler heuristics (number of lines).

Furthermore change the return type of flogr() to unsigned long and add the
const attribute to the function.

This reduces the kernel image size by 994 bytes (defconfig, gcc 15.2.0).

Suggested-by: default avatarJuergen Christ <jchrist@linux.ibm.com>
Reviewed-by: default avatarJuergen Christ <jchrist@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent 79161603

arch/s390/include/asm/bitops.h

+3 −4
Original line number Diff line number Diff line
@@ -130,7 +130,7 @@ static inline bool test_bit_inv(unsigned long nr, 
 * where the most significant bit has bit number 0.

 * If no bit is set this function returns 64.

 */

static __always_inline unsigned char __flogr(unsigned long word)

static __always_inline __attribute_const__ unsigned long __flogr(unsigned long word)

{

	unsigned long bit;
@@ -167,8 +167,7 @@ static __always_inline unsigned char __flogr(unsigned long word) 
		union register_pair rp __uninitialized;



		rp.even = word;

		asm volatile(

			"       flogr   %[rp],%[rp]\n"

		asm("flogr	%[rp],%[rp]"

		    : [rp] "+d" (rp.pair) : : "cc");

		bit = rp.even;

		/*