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* [glibc] x86: Improve svml_s_atanhf4_core_sse4.S
@ 2022-06-09 20:38 Noah Goldstein
0 siblings, 0 replies; only message in thread
From: Noah Goldstein @ 2022-06-09 20:38 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=fe1915d4f6dd5db92ce9d0be47c9d4e04f95946c
commit fe1915d4f6dd5db92ce9d0be47c9d4e04f95946c
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Thu Jun 9 09:58:31 2022 -0700
x86: Improve svml_s_atanhf4_core_sse4.S
Improvements are:
1. Reduce code size (-62 bytes).
2. Remove redundant move instructions.
3. Slightly improve instruction selection/scheduling where
possible.
4. Prefer registers which get short instruction encoding.
5. Reduce rodata usage (-16 bytes).
The throughput improvement is not significant as the port 0 bottleneck
is unavoidable.
Function, New Time, Old Time, New / Old
_ZGVbN4v_atanhf, 8.821, 8.903, 0.991
Diff:
---
.../fpu/multiarch/svml_s_atanhf4_core_sse4.S | 378 +++++++++------------
1 file changed, 169 insertions(+), 209 deletions(-)
diff --git a/sysdeps/x86_64/fpu/multiarch/svml_s_atanhf4_core_sse4.S b/sysdeps/x86_64/fpu/multiarch/svml_s_atanhf4_core_sse4.S
index 2d3ad2617f..37200b3601 100644
--- a/sysdeps/x86_64/fpu/multiarch/svml_s_atanhf4_core_sse4.S
+++ b/sysdeps/x86_64/fpu/multiarch/svml_s_atanhf4_core_sse4.S
@@ -30,96 +30,80 @@
*
*/
-/* Offsets for data table __svml_satanh_data_internal
- */
-#define SgnMask 0
-#define sOne 16
-#define sPoly 32
-#define iBrkValue 160
-#define iOffExpoMask 176
-#define sHalf 192
-#define sSign 208
-#define sTopMask12 224
-#define TinyRange 240
-#define sLn2 256
+/* Offsets for data table __svml_satanh_data_internal_avx512. Ordered
+ by use in the function. On cold-starts this might help the
+ prefetcher. Possibly a better idea is to interleave start/end so
+ that the prefetcher is less likely to detect a stream and pull
+ irrelivant lines into cache. */
+#define sOne 0
+#define SgnMask 16
+#define sTopMask12 32
+#define iBrkValue 48
+#define iOffExpoMask 64
+#define sPoly 80
+#define sLn2 208
+#define TinyRange 224
#include <sysdep.h>
+#define ATANHF_DATA(x) ((x)+__svml_satanh_data_internal)
.section .text.sse4, "ax", @progbits
ENTRY(_ZGVbN4v_atanhf_sse4)
- subq $72, %rsp
- cfi_def_cfa_offset(80)
movaps %xmm0, %xmm5
/* Load constants including One = 1 */
- movups sOne+__svml_satanh_data_internal(%rip), %xmm4
+ movups ATANHF_DATA(sOne)(%rip), %xmm4
movaps %xmm5, %xmm3
/* Strip off the sign, so treat X as positive until right at the end */
- movups SgnMask+__svml_satanh_data_internal(%rip), %xmm7
- movaps %xmm4, %xmm8
- andps %xmm5, %xmm7
+ movups ATANHF_DATA(SgnMask)(%rip), %xmm1
+ movaps %xmm4, %xmm2
+ andps %xmm1, %xmm0
movaps %xmm4, %xmm10
- movups sTopMask12+__svml_satanh_data_internal(%rip), %xmm11
+ movups ATANHF_DATA(sTopMask12)(%rip), %xmm11
movaps %xmm4, %xmm14
movaps %xmm11, %xmm9
+
/*
* Compute V = 2 * X trivially, and UHi + U_lo = 1 - X in two pieces,
* the upper part UHi being <= 12 bits long. Then we have
* atanh(X) = 1/2 * log((1 + X) / (1 - X)) = 1/2 * log1p(V / (UHi + ULo)).
*/
- movaps %xmm7, %xmm12
+ movaps %xmm0, %xmm6
+ mulps %xmm5, %xmm3
+ subps %xmm0, %xmm2
+ addps %xmm0, %xmm6
+ subps %xmm2, %xmm10
+ addps %xmm5, %xmm3
+ subps %xmm0, %xmm10
+ andps %xmm2, %xmm9
+
/*
* Check whether |X| < 1, in which case we use the main function.
* Otherwise set the rangemask so that the callout will get used.
* Note that this will also use the callout for NaNs since not(NaN < 1).
*/
- movaps %xmm7, %xmm6
- movaps %xmm7, %xmm2
- cmpnltps %xmm4, %xmm6
- cmpltps TinyRange+__svml_satanh_data_internal(%rip), %xmm2
- mulps %xmm5, %xmm3
- subps %xmm7, %xmm8
- addps %xmm7, %xmm12
- movmskps %xmm6, %edx
- subps %xmm8, %xmm10
- addps %xmm5, %xmm3
- subps %xmm7, %xmm10
- andps %xmm8, %xmm9
+ rcpps %xmm9, %xmm7
+ subps %xmm9, %xmm2
+ andps %xmm11, %xmm7
- /*
- * Now we feed into the log1p code, using H in place of _VARG1 and
- * later incorporating L into the reduced argument.
- * compute 1+x as high, low parts
- */
- movaps %xmm4, %xmm7
-
- /*
- * Now compute R = 1/(UHi+ULo) * (1 - E) and the error term E
- * The first FMR is exact (we force R to 12 bits just in case it
- * isn't already, to make absolutely sure), and since E is ~ 2^-12,
- * the rounding error in the other one is acceptable.
- */
- rcpps %xmm9, %xmm15
- subps %xmm9, %xmm8
- andps %xmm11, %xmm15
/*
* Split V as well into upper 12 bits and lower part, so that we can get
* a preliminary quotient estimate without rounding error.
*/
- andps %xmm12, %xmm11
- mulps %xmm15, %xmm9
- addps %xmm8, %xmm10
- subps %xmm11, %xmm12
+ andps %xmm6, %xmm11
+ mulps %xmm7, %xmm9
+ addps %xmm2, %xmm10
+ subps %xmm11, %xmm6
/* Hence get initial quotient estimate QHi + QLo = R * VHi + R * VLo */
- mulps %xmm15, %xmm11
- mulps %xmm15, %xmm10
+ mulps %xmm7, %xmm11
+ mulps %xmm7, %xmm10
subps %xmm9, %xmm14
- mulps %xmm12, %xmm15
+ mulps %xmm6, %xmm7
subps %xmm10, %xmm14
/* Compute D = E + E^2 */
@@ -127,8 +111,8 @@ ENTRY(_ZGVbN4v_atanhf_sse4)
movaps %xmm4, %xmm8
mulps %xmm14, %xmm13
- /* reduction: compute r, n */
- movdqu iBrkValue+__svml_satanh_data_internal(%rip), %xmm9
+ /* reduction: compute r,n */
+ movdqu ATANHF_DATA(iBrkValue)(%rip), %xmm9
addps %xmm13, %xmm14
/*
@@ -136,168 +120,149 @@ ENTRY(_ZGVbN4v_atanhf_sse4)
* = R * (VHi + VLo) * (1 + D)
* = QHi + (QHi * D + QLo + QLo * D)
*/
- movaps %xmm14, %xmm0
- mulps %xmm15, %xmm14
- mulps %xmm11, %xmm0
- addps %xmm14, %xmm15
- movdqu iOffExpoMask+__svml_satanh_data_internal(%rip), %xmm12
+ movaps %xmm14, %xmm2
+ mulps %xmm7, %xmm14
+ mulps %xmm11, %xmm2
+ addps %xmm14, %xmm7
+ movdqu ATANHF_DATA(iOffExpoMask)(%rip), %xmm12
movaps %xmm4, %xmm14
/* Record the sign for eventual reincorporation. */
- movups sSign+__svml_satanh_data_internal(%rip), %xmm1
- addps %xmm15, %xmm0
+ addps %xmm7, %xmm2
+
/*
* Now finally accumulate the high and low parts of the
* argument to log1p, H + L, with a final compensated summation.
*/
- movaps %xmm0, %xmm6
- andps %xmm5, %xmm1
-
+ movaps %xmm2, %xmm6
+ andnps %xmm5, %xmm1
+ movaps %xmm4, %xmm7
/* Or the sign bit in with the tiny result to handle atanh(-0) correctly */
- orps %xmm1, %xmm3
addps %xmm11, %xmm6
maxps %xmm6, %xmm7
minps %xmm6, %xmm8
subps %xmm6, %xmm11
movaps %xmm7, %xmm10
- andps %xmm2, %xmm3
addps %xmm8, %xmm10
- addps %xmm11, %xmm0
+ addps %xmm11, %xmm2
subps %xmm10, %xmm7
psubd %xmm9, %xmm10
- addps %xmm7, %xmm8
+ addps %xmm8, %xmm7
pand %xmm10, %xmm12
psrad $23, %xmm10
cvtdq2ps %xmm10, %xmm13
- addps %xmm8, %xmm0
+ addps %xmm7, %xmm2
/* final reconstruction */
- mulps sLn2+__svml_satanh_data_internal(%rip), %xmm13
pslld $23, %xmm10
paddd %xmm9, %xmm12
psubd %xmm10, %xmm14
/* polynomial evaluation */
subps %xmm4, %xmm12
- mulps %xmm0, %xmm14
- movups sPoly+112+__svml_satanh_data_internal(%rip), %xmm0
- addps %xmm12, %xmm14
- mulps %xmm14, %xmm0
+ mulps %xmm14, %xmm2
+ movups ATANHF_DATA(sPoly+0)(%rip), %xmm7
+ addps %xmm12, %xmm2
+ mulps %xmm2, %xmm7
+
/* Finally, halve the result and reincorporate the sign */
- movups sHalf+__svml_satanh_data_internal(%rip), %xmm4
- pxor %xmm1, %xmm4
- addps sPoly+96+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+80+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+64+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+48+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+32+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+16+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- addps sPoly+__svml_satanh_data_internal(%rip), %xmm0
- mulps %xmm14, %xmm0
- mulps %xmm14, %xmm0
- addps %xmm0, %xmm14
- movaps %xmm2, %xmm0
- addps %xmm13, %xmm14
- mulps %xmm14, %xmm4
- andnps %xmm4, %xmm0
- orps %xmm3, %xmm0
- testl %edx, %edx
+ addps ATANHF_DATA(sPoly+16)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ addps ATANHF_DATA(sPoly+32)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ addps ATANHF_DATA(sPoly+48)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ addps ATANHF_DATA(sPoly+64)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ addps ATANHF_DATA(sPoly+80)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ addps ATANHF_DATA(sPoly+96)(%rip), %xmm7
+ mulps %xmm2, %xmm7
+ movaps ATANHF_DATA(sPoly+112)(%rip), %xmm6
+ addps %xmm6, %xmm7
+ mulps %xmm2, %xmm7
+ mulps %xmm2, %xmm7
+ mulps ATANHF_DATA(sLn2)(%rip), %xmm13
+ /* We can build `sHalf` with `sPoly & sOne`. */
+ andps %xmm4, %xmm6
+ orps %xmm1, %xmm3
+ xorps %xmm6, %xmm1
- /* Go to special inputs processing branch */
- jne L(SPECIAL_VALUES_BRANCH)
- # LOE rbx rbp r12 r13 r14 r15 edx xmm0 xmm5
+ addps %xmm2, %xmm7
+ addps %xmm13, %xmm7
+ mulps %xmm7, %xmm1
- /* Restore registers
- * and exit the function
- */
+ /* Finish check of NaNs. */
+ cmpleps %xmm0, %xmm4
+ movmskps %xmm4, %edx
+ cmpltps ATANHF_DATA(TinyRange)(%rip), %xmm0
-L(EXIT):
- addq $72, %rsp
- cfi_def_cfa_offset(8)
+ andps %xmm0, %xmm3
+ andnps %xmm1, %xmm0
+ orps %xmm3, %xmm0
+
+ testl %edx, %edx
+ /* Go to special inputs processing branch. */
+ jne L(SPECIAL_VALUES_BRANCH)
+ # LOE rbx rbp r12 r13 r14 r15 xmm0
+ /* No registers to restore on fast path. */
ret
- cfi_def_cfa_offset(80)
- /* Branch to process
- * special inputs
- */
+ /* Cold case. edx has 1s where there was a special value that
+ needs to be handled by a atanhf call. Optimize for code size
+ more so than speed here. */
L(SPECIAL_VALUES_BRANCH):
- movups %xmm5, 32(%rsp)
- movups %xmm0, 48(%rsp)
- # LOE rbx rbp r12 r13 r14 r15 edx
-
- xorl %eax, %eax
- movq %r12, 16(%rsp)
- cfi_offset(12, -64)
- movl %eax, %r12d
- movq %r13, 8(%rsp)
- cfi_offset(13, -72)
- movl %edx, %r13d
- movq %r14, (%rsp)
- cfi_offset(14, -80)
- # LOE rbx rbp r15 r12d r13d
-
- /* Range mask
- * bits check
- */
-
-L(RANGEMASK_CHECK):
- btl %r12d, %r13d
-
- /* Call scalar math function */
- jc L(SCALAR_MATH_CALL)
- # LOE rbx rbp r15 r12d r13d
-
- /* Special inputs
- * processing loop
- */
-
+ # LOE rbx rdx rbp r12 r13 r14 r15 xmm0 xmm5
+ /* Stack coming in 16-byte aligned. Set 8-byte misaligned so on
+ call entry will be 16-byte aligned. */
+ subq $56, %rsp
+ cfi_def_cfa_offset(64)
+ movups %xmm0, 24(%rsp)
+ movups %xmm5, 40(%rsp)
+
+ /* Use rbx/rbp for callee save registers as they get short
+ encoding for many instructions (as compared with r12/r13). */
+ movq %rbx, (%rsp)
+ cfi_offset(rbx, -64)
+ movq %rbp, 8(%rsp)
+ cfi_offset(rbp, -56)
+ /* edx has 1s where there was a special value that needs to be handled
+ by a tanhf call. */
+ movl %edx, %ebx
L(SPECIAL_VALUES_LOOP):
- incl %r12d
- cmpl $4, %r12d
-
- /* Check bits in range mask */
- jl L(RANGEMASK_CHECK)
- # LOE rbx rbp r15 r12d r13d
-
- movq 16(%rsp), %r12
- cfi_restore(12)
- movq 8(%rsp), %r13
- cfi_restore(13)
- movq (%rsp), %r14
- cfi_restore(14)
- movups 48(%rsp), %xmm0
-
- /* Go to exit */
- jmp L(EXIT)
- cfi_offset(12, -64)
- cfi_offset(13, -72)
- cfi_offset(14, -80)
- # LOE rbx rbp r12 r13 r14 r15 xmm0
-
- /* Scalar math fucntion call
- * to process special input
- */
-
-L(SCALAR_MATH_CALL):
- movl %r12d, %r14d
- movss 32(%rsp, %r14, 4), %xmm0
+ # LOE rbx rbp r12 r13 r14 r15
+ /* use rbp as index for special value that is saved across calls to
+ tanhf. We technically don't need a callee save register here as offset
+ to rsp is always [0, 12] so we can restore rsp by realigning to 64.
+ Essentially the tradeoff is 1 extra save/restore vs 2 extra instructions
+ in the loop. */
+ xorl %ebp, %ebp
+ bsfl %ebx, %ebp
+
+ /* Scalar math fucntion call to process special input. */
+ movss 40(%rsp, %rbp, 4), %xmm0
call atanhf@PLT
- # LOE rbx rbp r14 r15 r12d r13d xmm0
-
- movss %xmm0, 48(%rsp, %r14, 4)
-
- /* Process special inputs in loop */
- jmp L(SPECIAL_VALUES_LOOP)
- # LOE rbx rbp r15 r12d r13d
+ /* No good way to avoid the store-forwarding fault this will cause on
+ return. `lfence` avoids the SF fault but at greater cost as it
+ serialized stack/callee save restoration. */
+ movss %xmm0, 24(%rsp, %rbp, 4)
+
+ leal -1(%rbx), %eax
+ andl %eax, %ebx
+ jnz L(SPECIAL_VALUES_LOOP)
+ # LOE r12 r13 r14 r15
+ /* All results have been written to 24(%rsp). */
+ movups 24(%rsp), %xmm0
+ movq (%rsp), %rbx
+ cfi_restore(rbx)
+ movq 8(%rsp), %rbp
+ cfi_restore(rbp)
+ addq $56, %rsp
+ cfi_def_cfa_offset(8)
+ ret
END(_ZGVbN4v_atanhf_sse4)
.section .rodata, "a"
@@ -305,56 +270,51 @@ END(_ZGVbN4v_atanhf_sse4)
#ifdef __svml_satanh_data_internal_typedef
typedef unsigned int VUINT32;
-typedef struct {
- __declspec(align(16)) VUINT32 SgnMask[4][1];
+typedef struct{
__declspec(align(16)) VUINT32 sOne[4][1];
- __declspec(align(16)) VUINT32 sPoly[8][4][1];
+ __declspec(align(16)) VUINT32 SgnMask[4][1];
+ __declspec(align(16)) VUINT32 sTopMask12[4][1];
__declspec(align(16)) VUINT32 iBrkValue[4][1];
__declspec(align(16)) VUINT32 iOffExpoMask[4][1];
- __declspec(align(16)) VUINT32 sHalf[4][1];
- __declspec(align(16)) VUINT32 sSign[4][1];
- __declspec(align(16)) VUINT32 sTopMask12[4][1];
- __declspec(align(16)) VUINT32 TinyRange[4][1];
+ __declspec(align(16)) VUINT32 sPoly[8][4][1];
__declspec(align(16)) VUINT32 sLn2[4][1];
+ __declspec(align(16)) VUINT32 TinyRange[4][1];
} __svml_satanh_data_internal;
#endif
+
__svml_satanh_data_internal:
- /* SgnMask */
- .long 0x7fffffff, 0x7fffffff, 0x7fffffff, 0x7fffffff
/* sOne = SP 1.0 */
.align 16
.long 0x3f800000, 0x3f800000, 0x3f800000, 0x3f800000
- /* sPoly[] = SP polynomial */
+ /* SgnMask */
+ .long 0x7fffffff, 0x7fffffff, 0x7fffffff, 0x7fffffff
+ /* sTopMask12 */
.align 16
- .long 0xbf000000, 0xbf000000, 0xbf000000, 0xbf000000 /* -5.0000000000000000000000000e-01 P0 */
- .long 0x3eaaaa94, 0x3eaaaa94, 0x3eaaaa94, 0x3eaaaa94 /* 3.3333265781402587890625000e-01 P1 */
- .long 0xbe80058e, 0xbe80058e, 0xbe80058e, 0xbe80058e /* -2.5004237890243530273437500e-01 P2 */
- .long 0x3e4ce190, 0x3e4ce190, 0x3e4ce190, 0x3e4ce190 /* 2.0007920265197753906250000e-01 P3 */
- .long 0xbe28ad37, 0xbe28ad37, 0xbe28ad37, 0xbe28ad37 /* -1.6472326219081878662109375e-01 P4 */
- .long 0x3e0fcb12, 0x3e0fcb12, 0x3e0fcb12, 0x3e0fcb12 /* 1.4042308926582336425781250e-01 P5 */
- .long 0xbe1ad9e3, 0xbe1ad9e3, 0xbe1ad9e3, 0xbe1ad9e3 /* -1.5122179687023162841796875e-01 P6 */
- .long 0x3e0d84ed, 0x3e0d84ed, 0x3e0d84ed, 0x3e0d84ed /* 1.3820238411426544189453125e-01 P7 */
+ .long 0xFFFFF000, 0xFFFFF000, 0xFFFFF000, 0xFFFFF000
/* iBrkValue = SP 2/3 */
.align 16
.long 0x3f2aaaab, 0x3f2aaaab, 0x3f2aaaab, 0x3f2aaaab
- /* iOffExpoMask = SP significand mask */
+ /* iOffExpoMask = SP significand mask ==*/
.align 16
.long 0x007fffff, 0x007fffff, 0x007fffff, 0x007fffff
- /* sHalf */
- .align 16
- .long 0x3F000000, 0x3F000000, 0x3F000000, 0x3F000000
- /* sSign */
+
+ /* sPoly[] = SP polynomial */
.align 16
- .long 0x80000000, 0x80000000, 0x80000000, 0x80000000
- /* sTopMask12 */
+ .long 0x3e0d84ed, 0x3e0d84ed, 0x3e0d84ed, 0x3e0d84ed /* 1.3820238411426544189453125e-01 P7 */
+ .long 0xbe1ad9e3, 0xbe1ad9e3, 0xbe1ad9e3, 0xbe1ad9e3 /* -1.5122179687023162841796875e-01 P6 */
+ .long 0x3e0fcb12, 0x3e0fcb12, 0x3e0fcb12, 0x3e0fcb12 /* 1.4042308926582336425781250e-01 P5 */
+ .long 0xbe28ad37, 0xbe28ad37, 0xbe28ad37, 0xbe28ad37 /* -1.6472326219081878662109375e-01 P4 */
+ .long 0x3e4ce190, 0x3e4ce190, 0x3e4ce190, 0x3e4ce190 /* 2.0007920265197753906250000e-01 P3 */
+ .long 0xbe80058e, 0xbe80058e, 0xbe80058e, 0xbe80058e /* -2.5004237890243530273437500e-01 P2 */
+ .long 0x3eaaaa94, 0x3eaaaa94, 0x3eaaaa94, 0x3eaaaa94 /* 3.3333265781402587890625000e-01 P1 */
+ .long 0xbf000000, 0xbf000000, 0xbf000000, 0xbf000000 /* -5.0000000000000000000000000e-01 P0 */
+
+ /* sLn2 = SP ln(2) */
.align 16
- .long 0xFFFFF000, 0xFFFFF000, 0xFFFFF000, 0xFFFFF000
+ .long 0x3f317218, 0x3f317218, 0x3f317218, 0x3f317218
/* TinyRange */
.align 16
.long 0x0C000000, 0x0C000000, 0x0C000000, 0x0C000000
- /* sLn2 = SP ln(2) */
- .align 16
- .long 0x3f317218, 0x3f317218, 0x3f317218, 0x3f317218
.align 16
.type __svml_satanh_data_internal, @object
.size __svml_satanh_data_internal, .-__svml_satanh_data_internal
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