linux_dsm_epyc7002/arch/sparc/lib/NG4memset.S
Babu Moger 0ae2d26ffe arch/sparc: Avoid DCTI Couples
Avoid un-intended DCTI Couples. Use of DCTI couples is deprecated.
Also address the "Programming Note" for optimal performance.

Here is the complete text from Oracle SPARC Architecture Specs.

6.3.4.7 DCTI Couples
"A delayed control transfer instruction (DCTI) in the delay slot of
another DCTI is referred to as a “DCTI couple”. The use of DCTI couples
is deprecated in the Oracle SPARC Architecture; no new software should
place a DCTI in the delay slot of another DCTI, because on future Oracle
SPARC Architecture implementations DCTI couples may execute either
slowly or differently than the programmer assumes it will.

SPARC V8 and SPARC V9 Compatibility Note
The SPARC V8 architecture left behavior undefined for a DCTI couple. The
SPARC V9 architecture defined behavior in that case, but as of
UltraSPARC Architecture 2005, use of DCTI couples was deprecated.
Software should not expect high performance from DCTI couples, and
performance of DCTI couples should be expected to decline further in
future processors.

Programming Note
As noted in TABLE 6-5 on page 115, an annulled branch-always
(branch-always with a = 1) instruction is not architecturally a DCTI.
However, since not all implementations make that distinction, for
optimal performance, a DCTI should not be placed in the instruction word
immediately following an annulled branch-always instruction (BA,A or
BPA,A)."

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Reviewed-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-27 21:51:40 -07:00

107 lines
2.2 KiB
ArmAsm

/* NG4memset.S: Niagara-4 optimized memset/bzero.
*
* Copyright (C) 2012 David S. Miller (davem@davemloft.net)
*/
#include <asm/asi.h>
.register %g2, #scratch
.register %g3, #scratch
.text
.align 32
.globl NG4memset
NG4memset:
andcc %o1, 0xff, %o4
be,pt %icc, 1f
mov %o2, %o1
sllx %o4, 8, %g1
or %g1, %o4, %o2
sllx %o2, 16, %g1
or %g1, %o2, %o2
sllx %o2, 32, %g1
ba,pt %icc, 1f
or %g1, %o2, %o4
.size NG4memset,.-NG4memset
.align 32
.globl NG4bzero
NG4bzero:
clr %o4
1: cmp %o1, 16
ble %icc, .Ltiny
mov %o0, %o3
sub %g0, %o0, %g1
and %g1, 0x7, %g1
brz,pt %g1, .Laligned8
sub %o1, %g1, %o1
1: stb %o4, [%o0 + 0x00]
subcc %g1, 1, %g1
bne,pt %icc, 1b
add %o0, 1, %o0
.Laligned8:
cmp %o1, 64 + (64 - 8)
ble .Lmedium
sub %g0, %o0, %g1
andcc %g1, (64 - 1), %g1
brz,pn %g1, .Laligned64
sub %o1, %g1, %o1
1: stx %o4, [%o0 + 0x00]
subcc %g1, 8, %g1
bne,pt %icc, 1b
add %o0, 0x8, %o0
.Laligned64:
andn %o1, 64 - 1, %g1
sub %o1, %g1, %o1
brnz,pn %o4, .Lnon_bzero_loop
mov 0x20, %g2
1: stxa %o4, [%o0 + %g0] ASI_BLK_INIT_QUAD_LDD_P
subcc %g1, 0x40, %g1
stxa %o4, [%o0 + %g2] ASI_BLK_INIT_QUAD_LDD_P
bne,pt %icc, 1b
add %o0, 0x40, %o0
.Lpostloop:
cmp %o1, 8
bl,pn %icc, .Ltiny
membar #StoreStore|#StoreLoad
.Lmedium:
andn %o1, 0x7, %g1
sub %o1, %g1, %o1
1: stx %o4, [%o0 + 0x00]
subcc %g1, 0x8, %g1
bne,pt %icc, 1b
add %o0, 0x08, %o0
andcc %o1, 0x4, %g1
be,pt %icc, .Ltiny
sub %o1, %g1, %o1
stw %o4, [%o0 + 0x00]
add %o0, 0x4, %o0
.Ltiny:
cmp %o1, 0
be,pn %icc, .Lexit
1: subcc %o1, 1, %o1
stb %o4, [%o0 + 0x00]
bne,pt %icc, 1b
add %o0, 1, %o0
.Lexit:
retl
mov %o3, %o0
.Lnon_bzero_loop:
mov 0x08, %g3
mov 0x28, %o5
1: stxa %o4, [%o0 + %g0] ASI_BLK_INIT_QUAD_LDD_P
subcc %g1, 0x40, %g1
stxa %o4, [%o0 + %g2] ASI_BLK_INIT_QUAD_LDD_P
stxa %o4, [%o0 + %g3] ASI_BLK_INIT_QUAD_LDD_P
stxa %o4, [%o0 + %o5] ASI_BLK_INIT_QUAD_LDD_P
add %o0, 0x10, %o0
stxa %o4, [%o0 + %g0] ASI_BLK_INIT_QUAD_LDD_P
stxa %o4, [%o0 + %g2] ASI_BLK_INIT_QUAD_LDD_P
stxa %o4, [%o0 + %g3] ASI_BLK_INIT_QUAD_LDD_P
stxa %o4, [%o0 + %o5] ASI_BLK_INIT_QUAD_LDD_P
bne,pt %icc, 1b
add %o0, 0x30, %o0
ba,a,pt %icc, .Lpostloop
nop
.size NG4bzero,.-NG4bzero