1 | /* Function log vectorized with SSE4. |
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.sse4, "ax" , @progbits |
23 | ENTRY (_ZGVbN2v_log_sse4) |
24 | /* |
25 | ALGORITHM DESCRIPTION: |
26 | |
27 | log(x) = -log(Rcp) + log(Rcp*x), |
28 | where Rcp ~ 1/x (accuracy ~9 bits, obtained by rounding |
29 | HW approximation to 1+9 mantissa bits) |
30 | |
31 | Reduced argument R=Rcp*x-1 is used to approximate log(1+R) as polynomial |
32 | |
33 | log(Rcp) = exponent_Rcp*log(2) + log(mantissa_Rcp) |
34 | -log(mantissa_Rcp) is obtained from a lookup table, |
35 | accessed by a 9-bit index |
36 | */ |
37 | pushq %rbp |
38 | cfi_adjust_cfa_offset (8) |
39 | cfi_rel_offset (%rbp, 0) |
40 | movq %rsp, %rbp |
41 | cfi_def_cfa_register (%rbp) |
42 | andq $-64, %rsp |
43 | subq $320, %rsp |
44 | movaps %xmm0, %xmm6 |
45 | movq __svml_dlog_data@GOTPCREL(%rip), %r8 |
46 | movaps %xmm6, %xmm3 |
47 | movaps %xmm6, %xmm2 |
48 | |
49 | /* isolate exponent bits */ |
50 | movaps %xmm6, %xmm1 |
51 | psrlq $20, %xmm1 |
52 | movups _ExpMask(%r8), %xmm5 |
53 | |
54 | /* preserve mantissa, set input exponent to 2^(-10) */ |
55 | andps %xmm6, %xmm5 |
56 | orps _Two10(%r8), %xmm5 |
57 | |
58 | /* reciprocal approximation good to at least 11 bits */ |
59 | cvtpd2ps %xmm5, %xmm7 |
60 | cmpltpd _MinNorm(%r8), %xmm3 |
61 | cmpnlepd _MaxNorm(%r8), %xmm2 |
62 | movlhps %xmm7, %xmm7 |
63 | |
64 | /* combine and get argument value range mask */ |
65 | orps %xmm2, %xmm3 |
66 | rcpps %xmm7, %xmm0 |
67 | movmskpd %xmm3, %eax |
68 | movups _HalfMask(%r8), %xmm2 |
69 | |
70 | /* argument reduction started: R = Mantissa*Rcp - 1 */ |
71 | andps %xmm5, %xmm2 |
72 | cvtps2pd %xmm0, %xmm4 |
73 | subpd %xmm2, %xmm5 |
74 | |
75 | /* round reciprocal to nearest integer, will have 1+9 mantissa bits */ |
76 | roundpd $0, %xmm4, %xmm4 |
77 | mulpd %xmm4, %xmm2 |
78 | mulpd %xmm4, %xmm5 |
79 | subpd _One(%r8), %xmm2 |
80 | addpd %xmm2, %xmm5 |
81 | movups _Threshold(%r8), %xmm2 |
82 | |
83 | /* calculate index for table lookup */ |
84 | movaps %xmm4, %xmm3 |
85 | cmpltpd %xmm4, %xmm2 |
86 | pshufd $221, %xmm1, %xmm7 |
87 | psrlq $40, %xmm3 |
88 | |
89 | /* convert biased exponent to DP format */ |
90 | cvtdq2pd %xmm7, %xmm0 |
91 | movd %xmm3, %edx |
92 | movups _poly_coeff_1(%r8), %xmm4 |
93 | |
94 | /* polynomial computation */ |
95 | mulpd %xmm5, %xmm4 |
96 | andps _Bias(%r8), %xmm2 |
97 | orps _Bias1(%r8), %xmm2 |
98 | |
99 | /* |
100 | Table stores -log(0.5*mantissa) for larger mantissas, |
101 | adjust exponent accordingly |
102 | */ |
103 | subpd %xmm2, %xmm0 |
104 | addpd _poly_coeff_2(%r8), %xmm4 |
105 | |
106 | /* exponent*log(2.0) */ |
107 | mulpd _L2(%r8), %xmm0 |
108 | movaps %xmm5, %xmm2 |
109 | mulpd %xmm5, %xmm2 |
110 | movups _poly_coeff_3(%r8), %xmm7 |
111 | mulpd %xmm5, %xmm7 |
112 | mulpd %xmm2, %xmm4 |
113 | addpd _poly_coeff_4(%r8), %xmm7 |
114 | addpd %xmm4, %xmm7 |
115 | mulpd %xmm7, %xmm2 |
116 | movslq %edx, %rdx |
117 | pextrd $2, %xmm3, %ecx |
118 | |
119 | /* |
120 | reconstruction: |
121 | (exponent*log(2)) + (LogRcp + (R+poly)) |
122 | */ |
123 | addpd %xmm2, %xmm5 |
124 | movslq %ecx, %rcx |
125 | movsd _LogRcp_lookup(%r8,%rdx), %xmm1 |
126 | movhpd _LogRcp_lookup(%r8,%rcx), %xmm1 |
127 | addpd %xmm5, %xmm1 |
128 | addpd %xmm1, %xmm0 |
129 | testl %eax, %eax |
130 | jne .LBL_1_3 |
131 | |
132 | .LBL_1_2: |
133 | cfi_remember_state |
134 | movq %rbp, %rsp |
135 | cfi_def_cfa_register (%rsp) |
136 | popq %rbp |
137 | cfi_adjust_cfa_offset (-8) |
138 | cfi_restore (%rbp) |
139 | ret |
140 | |
141 | .LBL_1_3: |
142 | cfi_restore_state |
143 | movups %xmm6, 192(%rsp) |
144 | movups %xmm0, 256(%rsp) |
145 | je .LBL_1_2 |
146 | |
147 | xorb %cl, %cl |
148 | xorl %edx, %edx |
149 | movups %xmm8, 112(%rsp) |
150 | movups %xmm9, 96(%rsp) |
151 | movups %xmm10, 80(%rsp) |
152 | movups %xmm11, 64(%rsp) |
153 | movups %xmm12, 48(%rsp) |
154 | movups %xmm13, 32(%rsp) |
155 | movups %xmm14, 16(%rsp) |
156 | movups %xmm15, (%rsp) |
157 | movq %rsi, 136(%rsp) |
158 | movq %rdi, 128(%rsp) |
159 | movq %r12, 168(%rsp) |
160 | cfi_offset_rel_rsp (12, 168) |
161 | movb %cl, %r12b |
162 | movq %r13, 160(%rsp) |
163 | cfi_offset_rel_rsp (13, 160) |
164 | movl %eax, %r13d |
165 | movq %r14, 152(%rsp) |
166 | cfi_offset_rel_rsp (14, 152) |
167 | movl %edx, %r14d |
168 | movq %r15, 144(%rsp) |
169 | cfi_offset_rel_rsp (15, 144) |
170 | cfi_remember_state |
171 | |
172 | .LBL_1_6: |
173 | btl %r14d, %r13d |
174 | jc .LBL_1_12 |
175 | |
176 | .LBL_1_7: |
177 | lea 1(%r14), %esi |
178 | btl %esi, %r13d |
179 | jc .LBL_1_10 |
180 | |
181 | .LBL_1_8: |
182 | incb %r12b |
183 | addl $2, %r14d |
184 | cmpb $16, %r12b |
185 | jb .LBL_1_6 |
186 | |
187 | movups 112(%rsp), %xmm8 |
188 | movups 96(%rsp), %xmm9 |
189 | movups 80(%rsp), %xmm10 |
190 | movups 64(%rsp), %xmm11 |
191 | movups 48(%rsp), %xmm12 |
192 | movups 32(%rsp), %xmm13 |
193 | movups 16(%rsp), %xmm14 |
194 | movups (%rsp), %xmm15 |
195 | movq 136(%rsp), %rsi |
196 | movq 128(%rsp), %rdi |
197 | movq 168(%rsp), %r12 |
198 | cfi_restore (%r12) |
199 | movq 160(%rsp), %r13 |
200 | cfi_restore (%r13) |
201 | movq 152(%rsp), %r14 |
202 | cfi_restore (%r14) |
203 | movq 144(%rsp), %r15 |
204 | cfi_restore (%r15) |
205 | movups 256(%rsp), %xmm0 |
206 | jmp .LBL_1_2 |
207 | |
208 | .LBL_1_10: |
209 | cfi_restore_state |
210 | movzbl %r12b, %r15d |
211 | shlq $4, %r15 |
212 | movsd 200(%rsp,%r15), %xmm0 |
213 | |
214 | call JUMPTARGET(log) |
215 | |
216 | movsd %xmm0, 264(%rsp,%r15) |
217 | jmp .LBL_1_8 |
218 | |
219 | .LBL_1_12: |
220 | movzbl %r12b, %r15d |
221 | shlq $4, %r15 |
222 | movsd 192(%rsp,%r15), %xmm0 |
223 | |
224 | call JUMPTARGET(log) |
225 | |
226 | movsd %xmm0, 256(%rsp,%r15) |
227 | jmp .LBL_1_7 |
228 | |
229 | END (_ZGVbN2v_log_sse4) |
230 | |