linux/arch/alpha/lib/ev6-memset.S
Richard Henderson a47e5bb576 alpha: Eliminate compiler warning from memset macro
Compiling with GCC 4.8 yields several instances of

crypto/vmac.c: In function ‘vmac_final’:
crypto/vmac.c:616:9: warning: value computed is not used [-Wunused-value]
  memset(&mac, 0, sizeof(vmac_t));
         ^
arch/alpha/include/asm/string.h:31:25: note: in definition of macro ‘memset’
     ? __builtin_memset((s),0,(n))          \
                         ^
Converting the macro to an inline function eliminates this problem.

However, doing only that causes problems with the GCC 3.x series.  The
inline function cannot be named "memset", as otherwise we wind up with
recursion via __builtin_memset.  Solve this by adjusting the symbols
such that __memset is the inline, and ___memset is the real function.

Signed-off-by: Richard Henderson <rth@twiddle.net>
2013-11-16 16:33:09 -08:00

600 lines
16 KiB
ArmAsm

/*
* arch/alpha/lib/ev6-memset.S
*
* This is an efficient (and relatively small) implementation of the C library
* "memset()" function for the 21264 implementation of Alpha.
*
* 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
*
* Much of the information about 21264 scheduling/coding comes from:
* Compiler Writer's Guide for the Alpha 21264
* abbreviated as 'CWG' in other comments here
* ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
* Scheduling notation:
* E - either cluster
* U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
* L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
* The algorithm for the leading and trailing quadwords remains the same,
* however the loop has been unrolled to enable better memory throughput,
* and the code has been replicated for each of the entry points: __memset
* and __memsetw to permit better scheduling to eliminate the stalling
* encountered during the mask replication.
* A future enhancement might be to put in a byte store loop for really
* small (say < 32 bytes) memset()s. Whether or not that change would be
* a win in the kernel would depend upon the contextual usage.
* WARNING: Maintaining this is going to be more work than the above version,
* as fixes will need to be made in multiple places. The performance gain
* is worth it.
*/
.set noat
.set noreorder
.text
.globl memset
.globl __memset
.globl ___memset
.globl __memsetw
.globl __constant_c_memset
.ent ___memset
.align 5
___memset:
.frame $30,0,$26,0
.prologue 0
/*
* Serious stalling happens. The only way to mitigate this is to
* undertake a major re-write to interleave the constant materialization
* with other parts of the fall-through code. This is important, even
* though it makes maintenance tougher.
* Do this later.
*/
and $17,255,$1 # E : 00000000000000ch
insbl $17,1,$2 # U : 000000000000ch00
bis $16,$16,$0 # E : return value
ble $18,end_b # U : zero length requested?
addq $18,$16,$6 # E : max address to write to
bis $1,$2,$17 # E : 000000000000chch
insbl $1,2,$3 # U : 0000000000ch0000
insbl $1,3,$4 # U : 00000000ch000000
or $3,$4,$3 # E : 00000000chch0000
inswl $17,4,$5 # U : 0000chch00000000
xor $16,$6,$1 # E : will complete write be within one quadword?
inswl $17,6,$2 # U : chch000000000000
or $17,$3,$17 # E : 00000000chchchch
or $2,$5,$2 # E : chchchch00000000
bic $1,7,$1 # E : fit within a single quadword?
and $16,7,$3 # E : Target addr misalignment
or $17,$2,$17 # E : chchchchchchchch
beq $1,within_quad_b # U :
nop # E :
beq $3,aligned_b # U : target is 0mod8
/*
* Target address is misaligned, and won't fit within a quadword
*/
ldq_u $4,0($16) # L : Fetch first partial
bis $16,$16,$5 # E : Save the address
insql $17,$16,$2 # U : Insert new bytes
subq $3,8,$3 # E : Invert (for addressing uses)
addq $18,$3,$18 # E : $18 is new count ($3 is negative)
mskql $4,$16,$4 # U : clear relevant parts of the quad
subq $16,$3,$16 # E : $16 is new aligned destination
bis $2,$4,$1 # E : Final bytes
nop
stq_u $1,0($5) # L : Store result
nop
nop
.align 4
aligned_b:
/*
* We are now guaranteed to be quad aligned, with at least
* one partial quad to write.
*/
sra $18,3,$3 # U : Number of remaining quads to write
and $18,7,$18 # E : Number of trailing bytes to write
bis $16,$16,$5 # E : Save dest address
beq $3,no_quad_b # U : tail stuff only
/*
* it's worth the effort to unroll this and use wh64 if possible
* Lifted a bunch of code from clear_user.S
* At this point, entry values are:
* $16 Current destination address
* $5 A copy of $16
* $6 The max quadword address to write to
* $18 Number trailer bytes
* $3 Number quads to write
*/
and $16, 0x3f, $2 # E : Forward work (only useful for unrolled loop)
subq $3, 16, $4 # E : Only try to unroll if > 128 bytes
subq $2, 0x40, $1 # E : bias counter (aligning stuff 0mod64)
blt $4, loop_b # U :
/*
* We know we've got at least 16 quads, minimum of one trip
* through unrolled loop. Do a quad at a time to get us 0mod64
* aligned.
*/
nop # E :
nop # E :
nop # E :
beq $1, $bigalign_b # U :
$alignmod64_b:
stq $17, 0($5) # L :
subq $3, 1, $3 # E : For consistency later
addq $1, 8, $1 # E : Increment towards zero for alignment
addq $5, 8, $4 # E : Initial wh64 address (filler instruction)
nop
nop
addq $5, 8, $5 # E : Inc address
blt $1, $alignmod64_b # U :
$bigalign_b:
/*
* $3 - number quads left to go
* $5 - target address (aligned 0mod64)
* $17 - mask of stuff to store
* Scratch registers available: $7, $2, $4, $1
* we know that we'll be taking a minimum of one trip through
* CWG Section 3.7.6: do not expect a sustained store rate of > 1/cycle
* Assumes the wh64 needs to be for 2 trips through the loop in the future
* The wh64 is issued on for the starting destination address for trip +2
* through the loop, and if there are less than two trips left, the target
* address will be for the current trip.
*/
$do_wh64_b:
wh64 ($4) # L1 : memory subsystem write hint
subq $3, 24, $2 # E : For determining future wh64 addresses
stq $17, 0($5) # L :
nop # E :
addq $5, 128, $4 # E : speculative target of next wh64
stq $17, 8($5) # L :
stq $17, 16($5) # L :
addq $5, 64, $7 # E : Fallback address for wh64 (== next trip addr)
stq $17, 24($5) # L :
stq $17, 32($5) # L :
cmovlt $2, $7, $4 # E : Latency 2, extra mapping cycle
nop
stq $17, 40($5) # L :
stq $17, 48($5) # L :
subq $3, 16, $2 # E : Repeat the loop at least once more?
nop
stq $17, 56($5) # L :
addq $5, 64, $5 # E :
subq $3, 8, $3 # E :
bge $2, $do_wh64_b # U :
nop
nop
nop
beq $3, no_quad_b # U : Might have finished already
.align 4
/*
* Simple loop for trailing quadwords, or for small amounts
* of data (where we can't use an unrolled loop and wh64)
*/
loop_b:
stq $17,0($5) # L :
subq $3,1,$3 # E : Decrement number quads left
addq $5,8,$5 # E : Inc address
bne $3,loop_b # U : more?
no_quad_b:
/*
* Write 0..7 trailing bytes.
*/
nop # E :
beq $18,end_b # U : All done?
ldq $7,0($5) # L :
mskqh $7,$6,$2 # U : Mask final quad
insqh $17,$6,$4 # U : New bits
bis $2,$4,$1 # E : Put it all together
stq $1,0($5) # L : And back to memory
ret $31,($26),1 # L0 :
within_quad_b:
ldq_u $1,0($16) # L :
insql $17,$16,$2 # U : New bits
mskql $1,$16,$4 # U : Clear old
bis $2,$4,$2 # E : New result
mskql $2,$6,$4 # U :
mskqh $1,$6,$2 # U :
bis $2,$4,$1 # E :
stq_u $1,0($16) # L :
end_b:
nop
nop
nop
ret $31,($26),1 # L0 :
.end ___memset
/*
* This is the original body of code, prior to replication and
* rescheduling. Leave it here, as there may be calls to this
* entry point.
*/
.align 4
.ent __constant_c_memset
__constant_c_memset:
.frame $30,0,$26,0
.prologue 0
addq $18,$16,$6 # E : max address to write to
bis $16,$16,$0 # E : return value
xor $16,$6,$1 # E : will complete write be within one quadword?
ble $18,end # U : zero length requested?
bic $1,7,$1 # E : fit within a single quadword
beq $1,within_one_quad # U :
and $16,7,$3 # E : Target addr misalignment
beq $3,aligned # U : target is 0mod8
/*
* Target address is misaligned, and won't fit within a quadword
*/
ldq_u $4,0($16) # L : Fetch first partial
bis $16,$16,$5 # E : Save the address
insql $17,$16,$2 # U : Insert new bytes
subq $3,8,$3 # E : Invert (for addressing uses)
addq $18,$3,$18 # E : $18 is new count ($3 is negative)
mskql $4,$16,$4 # U : clear relevant parts of the quad
subq $16,$3,$16 # E : $16 is new aligned destination
bis $2,$4,$1 # E : Final bytes
nop
stq_u $1,0($5) # L : Store result
nop
nop
.align 4
aligned:
/*
* We are now guaranteed to be quad aligned, with at least
* one partial quad to write.
*/
sra $18,3,$3 # U : Number of remaining quads to write
and $18,7,$18 # E : Number of trailing bytes to write
bis $16,$16,$5 # E : Save dest address
beq $3,no_quad # U : tail stuff only
/*
* it's worth the effort to unroll this and use wh64 if possible
* Lifted a bunch of code from clear_user.S
* At this point, entry values are:
* $16 Current destination address
* $5 A copy of $16
* $6 The max quadword address to write to
* $18 Number trailer bytes
* $3 Number quads to write
*/
and $16, 0x3f, $2 # E : Forward work (only useful for unrolled loop)
subq $3, 16, $4 # E : Only try to unroll if > 128 bytes
subq $2, 0x40, $1 # E : bias counter (aligning stuff 0mod64)
blt $4, loop # U :
/*
* We know we've got at least 16 quads, minimum of one trip
* through unrolled loop. Do a quad at a time to get us 0mod64
* aligned.
*/
nop # E :
nop # E :
nop # E :
beq $1, $bigalign # U :
$alignmod64:
stq $17, 0($5) # L :
subq $3, 1, $3 # E : For consistency later
addq $1, 8, $1 # E : Increment towards zero for alignment
addq $5, 8, $4 # E : Initial wh64 address (filler instruction)
nop
nop
addq $5, 8, $5 # E : Inc address
blt $1, $alignmod64 # U :
$bigalign:
/*
* $3 - number quads left to go
* $5 - target address (aligned 0mod64)
* $17 - mask of stuff to store
* Scratch registers available: $7, $2, $4, $1
* we know that we'll be taking a minimum of one trip through
* CWG Section 3.7.6: do not expect a sustained store rate of > 1/cycle
* Assumes the wh64 needs to be for 2 trips through the loop in the future
* The wh64 is issued on for the starting destination address for trip +2
* through the loop, and if there are less than two trips left, the target
* address will be for the current trip.
*/
$do_wh64:
wh64 ($4) # L1 : memory subsystem write hint
subq $3, 24, $2 # E : For determining future wh64 addresses
stq $17, 0($5) # L :
nop # E :
addq $5, 128, $4 # E : speculative target of next wh64
stq $17, 8($5) # L :
stq $17, 16($5) # L :
addq $5, 64, $7 # E : Fallback address for wh64 (== next trip addr)
stq $17, 24($5) # L :
stq $17, 32($5) # L :
cmovlt $2, $7, $4 # E : Latency 2, extra mapping cycle
nop
stq $17, 40($5) # L :
stq $17, 48($5) # L :
subq $3, 16, $2 # E : Repeat the loop at least once more?
nop
stq $17, 56($5) # L :
addq $5, 64, $5 # E :
subq $3, 8, $3 # E :
bge $2, $do_wh64 # U :
nop
nop
nop
beq $3, no_quad # U : Might have finished already
.align 4
/*
* Simple loop for trailing quadwords, or for small amounts
* of data (where we can't use an unrolled loop and wh64)
*/
loop:
stq $17,0($5) # L :
subq $3,1,$3 # E : Decrement number quads left
addq $5,8,$5 # E : Inc address
bne $3,loop # U : more?
no_quad:
/*
* Write 0..7 trailing bytes.
*/
nop # E :
beq $18,end # U : All done?
ldq $7,0($5) # L :
mskqh $7,$6,$2 # U : Mask final quad
insqh $17,$6,$4 # U : New bits
bis $2,$4,$1 # E : Put it all together
stq $1,0($5) # L : And back to memory
ret $31,($26),1 # L0 :
within_one_quad:
ldq_u $1,0($16) # L :
insql $17,$16,$2 # U : New bits
mskql $1,$16,$4 # U : Clear old
bis $2,$4,$2 # E : New result
mskql $2,$6,$4 # U :
mskqh $1,$6,$2 # U :
bis $2,$4,$1 # E :
stq_u $1,0($16) # L :
end:
nop
nop
nop
ret $31,($26),1 # L0 :
.end __constant_c_memset
/*
* This is a replicant of the __constant_c_memset code, rescheduled
* to mask stalls. Note that entry point names also had to change
*/
.align 5
.ent __memsetw
__memsetw:
.frame $30,0,$26,0
.prologue 0
inswl $17,0,$5 # U : 000000000000c1c2
inswl $17,2,$2 # U : 00000000c1c20000
bis $16,$16,$0 # E : return value
addq $18,$16,$6 # E : max address to write to
ble $18, end_w # U : zero length requested?
inswl $17,4,$3 # U : 0000c1c200000000
inswl $17,6,$4 # U : c1c2000000000000
xor $16,$6,$1 # E : will complete write be within one quadword?
or $2,$5,$2 # E : 00000000c1c2c1c2
or $3,$4,$17 # E : c1c2c1c200000000
bic $1,7,$1 # E : fit within a single quadword
and $16,7,$3 # E : Target addr misalignment
or $17,$2,$17 # E : c1c2c1c2c1c2c1c2
beq $1,within_quad_w # U :
nop
beq $3,aligned_w # U : target is 0mod8
/*
* Target address is misaligned, and won't fit within a quadword
*/
ldq_u $4,0($16) # L : Fetch first partial
bis $16,$16,$5 # E : Save the address
insql $17,$16,$2 # U : Insert new bytes
subq $3,8,$3 # E : Invert (for addressing uses)
addq $18,$3,$18 # E : $18 is new count ($3 is negative)
mskql $4,$16,$4 # U : clear relevant parts of the quad
subq $16,$3,$16 # E : $16 is new aligned destination
bis $2,$4,$1 # E : Final bytes
nop
stq_u $1,0($5) # L : Store result
nop
nop
.align 4
aligned_w:
/*
* We are now guaranteed to be quad aligned, with at least
* one partial quad to write.
*/
sra $18,3,$3 # U : Number of remaining quads to write
and $18,7,$18 # E : Number of trailing bytes to write
bis $16,$16,$5 # E : Save dest address
beq $3,no_quad_w # U : tail stuff only
/*
* it's worth the effort to unroll this and use wh64 if possible
* Lifted a bunch of code from clear_user.S
* At this point, entry values are:
* $16 Current destination address
* $5 A copy of $16
* $6 The max quadword address to write to
* $18 Number trailer bytes
* $3 Number quads to write
*/
and $16, 0x3f, $2 # E : Forward work (only useful for unrolled loop)
subq $3, 16, $4 # E : Only try to unroll if > 128 bytes
subq $2, 0x40, $1 # E : bias counter (aligning stuff 0mod64)
blt $4, loop_w # U :
/*
* We know we've got at least 16 quads, minimum of one trip
* through unrolled loop. Do a quad at a time to get us 0mod64
* aligned.
*/
nop # E :
nop # E :
nop # E :
beq $1, $bigalign_w # U :
$alignmod64_w:
stq $17, 0($5) # L :
subq $3, 1, $3 # E : For consistency later
addq $1, 8, $1 # E : Increment towards zero for alignment
addq $5, 8, $4 # E : Initial wh64 address (filler instruction)
nop
nop
addq $5, 8, $5 # E : Inc address
blt $1, $alignmod64_w # U :
$bigalign_w:
/*
* $3 - number quads left to go
* $5 - target address (aligned 0mod64)
* $17 - mask of stuff to store
* Scratch registers available: $7, $2, $4, $1
* we know that we'll be taking a minimum of one trip through
* CWG Section 3.7.6: do not expect a sustained store rate of > 1/cycle
* Assumes the wh64 needs to be for 2 trips through the loop in the future
* The wh64 is issued on for the starting destination address for trip +2
* through the loop, and if there are less than two trips left, the target
* address will be for the current trip.
*/
$do_wh64_w:
wh64 ($4) # L1 : memory subsystem write hint
subq $3, 24, $2 # E : For determining future wh64 addresses
stq $17, 0($5) # L :
nop # E :
addq $5, 128, $4 # E : speculative target of next wh64
stq $17, 8($5) # L :
stq $17, 16($5) # L :
addq $5, 64, $7 # E : Fallback address for wh64 (== next trip addr)
stq $17, 24($5) # L :
stq $17, 32($5) # L :
cmovlt $2, $7, $4 # E : Latency 2, extra mapping cycle
nop
stq $17, 40($5) # L :
stq $17, 48($5) # L :
subq $3, 16, $2 # E : Repeat the loop at least once more?
nop
stq $17, 56($5) # L :
addq $5, 64, $5 # E :
subq $3, 8, $3 # E :
bge $2, $do_wh64_w # U :
nop
nop
nop
beq $3, no_quad_w # U : Might have finished already
.align 4
/*
* Simple loop for trailing quadwords, or for small amounts
* of data (where we can't use an unrolled loop and wh64)
*/
loop_w:
stq $17,0($5) # L :
subq $3,1,$3 # E : Decrement number quads left
addq $5,8,$5 # E : Inc address
bne $3,loop_w # U : more?
no_quad_w:
/*
* Write 0..7 trailing bytes.
*/
nop # E :
beq $18,end_w # U : All done?
ldq $7,0($5) # L :
mskqh $7,$6,$2 # U : Mask final quad
insqh $17,$6,$4 # U : New bits
bis $2,$4,$1 # E : Put it all together
stq $1,0($5) # L : And back to memory
ret $31,($26),1 # L0 :
within_quad_w:
ldq_u $1,0($16) # L :
insql $17,$16,$2 # U : New bits
mskql $1,$16,$4 # U : Clear old
bis $2,$4,$2 # E : New result
mskql $2,$6,$4 # U :
mskqh $1,$6,$2 # U :
bis $2,$4,$1 # E :
stq_u $1,0($16) # L :
end_w:
nop
nop
nop
ret $31,($26),1 # L0 :
.end __memsetw
memset = ___memset
__memset = ___memset