Commit 6ec27475 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by David S. Miller
Browse files

sparc64: simple microoptimizations for atomic functions 



Simple microoptimizations for sparc64 atomic functions:
Save one instruction by using a delay slot.
Use %g1 instead of %g7, because %g1 is written earlier.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9b3bb86a

arch/sparc/lib/atomic_64.S

+8 −12
Original line number Diff line number Diff line
@@ -52,10 +52,9 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */ 
	cas	[%o1], %g1, %g7

	cmp	%g1, %g7

	bne,pn	%icc, 2f

	 add	%g7, %o0, %g7

	sra	%g7, 0, %o0

	 add	%g1, %o0, %g1

	retl

	 nop

	 sra	%g1, 0, %o0

2:	BACKOFF_SPIN(%o2, %o3, 1b)

	.size	atomic_add_ret, .-atomic_add_ret
@@ -68,10 +67,9 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */ 
	cas	[%o1], %g1, %g7

	cmp	%g1, %g7

	bne,pn	%icc, 2f

	 sub	%g7, %o0, %g7

	sra	%g7, 0, %o0

	 sub	%g1, %o0, %g1

	retl

	 nop

	 sra	%g1, 0, %o0

2:	BACKOFF_SPIN(%o2, %o3, 1b)

	.size	atomic_sub_ret, .-atomic_sub_ret
@@ -114,10 +112,9 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */ 
	casx	[%o1], %g1, %g7

	cmp	%g1, %g7

	bne,pn	%xcc, 2f

	 add	%g7, %o0, %g7

	mov	%g7, %o0

	retl

	 nop

	retl

	 add	%g1, %o0, %o0

2:	BACKOFF_SPIN(%o2, %o3, 1b)

	.size	atomic64_add_ret, .-atomic64_add_ret
@@ -130,9 +127,8 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */ 
	casx	[%o1], %g1, %g7

	cmp	%g1, %g7

	bne,pn	%xcc, 2f

	 sub	%g7, %o0, %g7

	mov	%g7, %o0

	retl

	 nop

	retl

	 sub	%g1, %o0, %o0

2:	BACKOFF_SPIN(%o2, %o3, 1b)

	.size	atomic64_sub_ret, .-atomic64_sub_ret

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