1 | /* Function log vectorized with AVX2. |
2 | Copyright (C) 2014-2024 Free Software Foundation, Inc. |
3 | This file is part of the GNU C Library. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <sysdep.h> |
20 | #include "svml_d_log_data.h" |
21 | |
22 | .section .text.avx2, "ax" , @progbits |
23 | ENTRY (_ZGVdN4v_log_avx2) |
24 | /* ALGORITHM DESCRIPTION: |
25 | |
26 | log(x) = -log(Rcp) + log(Rcp*x), |
27 | where Rcp ~ 1/x (accuracy ~9 bits, obtained by rounding |
28 | HW approximation to 1+9 mantissa bits) |
29 | |
30 | Reduced argument R=Rcp*x-1 is used to approximate log(1+R) as polynomial |
31 | |
32 | log(Rcp) = exponent_Rcp*log(2) + log(mantissa_Rcp) |
33 | -log(mantissa_Rcp) is obtained from a lookup table, |
34 | accessed by a 9-bit index |
35 | */ |
36 | pushq %rbp |
37 | cfi_adjust_cfa_offset (8) |
38 | cfi_rel_offset (%rbp, 0) |
39 | movq %rsp, %rbp |
40 | cfi_def_cfa_register (%rbp) |
41 | andq $-64, %rsp |
42 | subq $448, %rsp |
43 | movq __svml_dlog_data@GOTPCREL(%rip), %rax |
44 | vmovdqa %ymm0, %ymm5 |
45 | |
46 | /* isolate exponent bits */ |
47 | vpsrlq $20, %ymm5, %ymm0 |
48 | |
49 | /* preserve mantissa, set input exponent to 2^(-10) */ |
50 | vandpd _ExpMask(%rax), %ymm5, %ymm6 |
51 | vorpd _Two10(%rax), %ymm6, %ymm4 |
52 | |
53 | /* reciprocal approximation good to at least 11 bits */ |
54 | vcvtpd2ps %ymm4, %xmm7 |
55 | vrcpps %xmm7, %xmm1 |
56 | vcmplt_oqpd _MinNorm(%rax), %ymm5, %ymm7 |
57 | vcvtps2pd %xmm1, %ymm3 |
58 | vcmpnle_uqpd _MaxNorm(%rax), %ymm5, %ymm1 |
59 | vextracti128 $1, %ymm0, %xmm2 |
60 | vshufps $221, %xmm2, %xmm0, %xmm6 |
61 | |
62 | /* round reciprocal to nearest integer, will have 1+9 mantissa bits */ |
63 | vroundpd $0, %ymm3, %ymm2 |
64 | |
65 | /* convert biased exponent to DP format */ |
66 | vcvtdq2pd %xmm6, %ymm0 |
67 | |
68 | /* combine and get argument value range mask */ |
69 | vorpd %ymm1, %ymm7, %ymm3 |
70 | vmovupd _One(%rax), %ymm1 |
71 | vmovmskpd %ymm3, %ecx |
72 | |
73 | /* calculate index for table lookup */ |
74 | vpsrlq $40, %ymm2, %ymm3 |
75 | |
76 | /* argument reduction started: R = Mantissa*Rcp - 1 */ |
77 | vfmsub213pd %ymm1, %ymm2, %ymm4 |
78 | vcmpgt_oqpd _Threshold(%rax), %ymm2, %ymm2 |
79 | vpcmpeqd %ymm6, %ymm6, %ymm6 |
80 | vxorpd %ymm1, %ymm1, %ymm1 |
81 | vgatherqpd %ymm6, _LogRcp_lookup(%rax,%ymm3), %ymm1 |
82 | |
83 | /* exponent*log(2.0) */ |
84 | vmovupd _poly_coeff_1(%rax), %ymm6 |
85 | vmulpd %ymm4, %ymm4, %ymm3 |
86 | |
87 | /* polynomial computation */ |
88 | vfmadd213pd _poly_coeff_2(%rax), %ymm4, %ymm6 |
89 | vandpd _Bias(%rax), %ymm2, %ymm7 |
90 | vorpd _Bias1(%rax), %ymm7, %ymm2 |
91 | |
92 | /* |
93 | Table stores -log(0.5*mantissa) for larger mantissas, |
94 | adjust exponent accordingly |
95 | */ |
96 | vsubpd %ymm2, %ymm0, %ymm0 |
97 | vmovupd _poly_coeff_3(%rax), %ymm2 |
98 | vfmadd213pd _poly_coeff_4(%rax), %ymm4, %ymm2 |
99 | vfmadd213pd %ymm2, %ymm3, %ymm6 |
100 | |
101 | /* |
102 | reconstruction: |
103 | (exponent*log(2)) + (LogRcp + (R+poly)) |
104 | */ |
105 | vfmadd213pd %ymm4, %ymm3, %ymm6 |
106 | vaddpd %ymm1, %ymm6, %ymm4 |
107 | vfmadd132pd _L2(%rax), %ymm4, %ymm0 |
108 | testl %ecx, %ecx |
109 | jne .LBL_1_3 |
110 | |
111 | .LBL_1_2: |
112 | cfi_remember_state |
113 | movq %rbp, %rsp |
114 | cfi_def_cfa_register (%rsp) |
115 | popq %rbp |
116 | cfi_adjust_cfa_offset (-8) |
117 | cfi_restore (%rbp) |
118 | ret |
119 | |
120 | .LBL_1_3: |
121 | cfi_restore_state |
122 | vmovupd %ymm5, 320(%rsp) |
123 | vmovupd %ymm0, 384(%rsp) |
124 | je .LBL_1_2 |
125 | |
126 | xorb %dl, %dl |
127 | xorl %eax, %eax |
128 | vmovups %ymm8, 224(%rsp) |
129 | vmovups %ymm9, 192(%rsp) |
130 | vmovups %ymm10, 160(%rsp) |
131 | vmovups %ymm11, 128(%rsp) |
132 | vmovups %ymm12, 96(%rsp) |
133 | vmovups %ymm13, 64(%rsp) |
134 | vmovups %ymm14, 32(%rsp) |
135 | vmovups %ymm15, (%rsp) |
136 | movq %rsi, 264(%rsp) |
137 | movq %rdi, 256(%rsp) |
138 | movq %r12, 296(%rsp) |
139 | cfi_offset_rel_rsp (12, 296) |
140 | movb %dl, %r12b |
141 | movq %r13, 288(%rsp) |
142 | cfi_offset_rel_rsp (13, 288) |
143 | movl %ecx, %r13d |
144 | movq %r14, 280(%rsp) |
145 | cfi_offset_rel_rsp (14, 280) |
146 | movl %eax, %r14d |
147 | movq %r15, 272(%rsp) |
148 | cfi_offset_rel_rsp (15, 272) |
149 | cfi_remember_state |
150 | |
151 | .LBL_1_6: |
152 | btl %r14d, %r13d |
153 | jc .LBL_1_12 |
154 | |
155 | .LBL_1_7: |
156 | lea 1(%r14), %esi |
157 | btl %esi, %r13d |
158 | jc .LBL_1_10 |
159 | |
160 | .LBL_1_8: |
161 | incb %r12b |
162 | addl $2, %r14d |
163 | cmpb $16, %r12b |
164 | jb .LBL_1_6 |
165 | |
166 | vmovups 224(%rsp), %ymm8 |
167 | vmovups 192(%rsp), %ymm9 |
168 | vmovups 160(%rsp), %ymm10 |
169 | vmovups 128(%rsp), %ymm11 |
170 | vmovups 96(%rsp), %ymm12 |
171 | vmovups 64(%rsp), %ymm13 |
172 | vmovups 32(%rsp), %ymm14 |
173 | vmovups (%rsp), %ymm15 |
174 | vmovupd 384(%rsp), %ymm0 |
175 | movq 264(%rsp), %rsi |
176 | movq 256(%rsp), %rdi |
177 | movq 296(%rsp), %r12 |
178 | cfi_restore (%r12) |
179 | movq 288(%rsp), %r13 |
180 | cfi_restore (%r13) |
181 | movq 280(%rsp), %r14 |
182 | cfi_restore (%r14) |
183 | movq 272(%rsp), %r15 |
184 | cfi_restore (%r15) |
185 | jmp .LBL_1_2 |
186 | |
187 | .LBL_1_10: |
188 | cfi_restore_state |
189 | movzbl %r12b, %r15d |
190 | shlq $4, %r15 |
191 | vmovsd 328(%rsp,%r15), %xmm0 |
192 | vzeroupper |
193 | |
194 | call JUMPTARGET(log) |
195 | |
196 | vmovsd %xmm0, 392(%rsp,%r15) |
197 | jmp .LBL_1_8 |
198 | |
199 | .LBL_1_12: |
200 | movzbl %r12b, %r15d |
201 | shlq $4, %r15 |
202 | vmovsd 320(%rsp,%r15), %xmm0 |
203 | vzeroupper |
204 | |
205 | call JUMPTARGET(log) |
206 | |
207 | vmovsd %xmm0, 384(%rsp,%r15) |
208 | jmp .LBL_1_7 |
209 | |
210 | END (_ZGVdN4v_log_avx2) |
211 | |