x86-64: Add vector log2/log2f implementation to libmvec

Implement vectorized log2/log2f containing SSE, AVX, AVX2 and
AVX512 versions for libmvec as per vector ABI.  It also contains
accuracy and ABI tests for vector log2/log2f with regenerated ulps.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

1 files changed, 293 insertions, 0 deletions

diff --git a/sysdeps/x86_64/fpu/multiarch/svml_d_log28_core_avx512.S b/sysdeps/x86_64/fpu/multiarch/svml_d_log28_core_avx512.S
new file mode 100644
index 0000000000..211a78f315
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/svml_d_log28_core_avx512.S
@@ -0,0 +1,293 @@
+/* Function log2 vectorized with AVX-512.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   https://www.gnu.org/licenses/.  */
+
+/*
+ * ALGORITHM DESCRIPTION:
+ *
+ *    Get short reciprocal approximation Rcp ~ 1/mantissa(x)
+ *    R = Rcp*x - 1.0
+ *    log2(x) = k - log2(Rcp) + poly_approximation(R)
+ *       log2(Rcp) is tabulated
+ *
+ *
+ */
+
+/* Offsets for data table __svml_dlog2_data_internal_avx512
+ */
+#define Log_tbl                       	0
+#define One                           	128
+#define C075                          	192
+#define poly_coeff9                   	256
+#define poly_coeff8                   	320
+#define poly_coeff7                   	384
+#define poly_coeff6                   	448
+#define poly_coeff5                   	512
+#define poly_coeff4                   	576
+#define poly_coeff3                   	640
+#define poly_coeff2                   	704
+#define poly_coeff1                   	768
+
+#include <sysdep.h>
+
+        .text
+	.section .text.evex512,"ax",@progbits
+ENTRY(_ZGVeN8v_log2_skx)
+        pushq     %rbp
+        cfi_def_cfa_offset(16)
+        movq      %rsp, %rbp
+        cfi_def_cfa(6, 16)
+        cfi_offset(6, -16)
+        andq      $-64, %rsp
+        subq      $192, %rsp
+        vmovaps   %zmm0, %zmm7
+        vgetmantpd $8, {sae}, %zmm7, %zmm6
+        vmovups   One+__svml_dlog2_data_internal_avx512(%rip), %zmm2
+        vmovups   poly_coeff5+__svml_dlog2_data_internal_avx512(%rip), %zmm12
+        vmovups   poly_coeff3+__svml_dlog2_data_internal_avx512(%rip), %zmm13
+
+/* Start polynomial evaluation */
+        vmovups   poly_coeff9+__svml_dlog2_data_internal_avx512(%rip), %zmm10
+        vmovups   poly_coeff8+__svml_dlog2_data_internal_avx512(%rip), %zmm0
+        vmovups   poly_coeff7+__svml_dlog2_data_internal_avx512(%rip), %zmm11
+        vmovups   poly_coeff6+__svml_dlog2_data_internal_avx512(%rip), %zmm14
+
+/* Prepare exponent correction: DblRcp<0.75? */
+        vmovups   C075+__svml_dlog2_data_internal_avx512(%rip), %zmm1
+
+/* Table lookup */
+        vmovups   __svml_dlog2_data_internal_avx512(%rip), %zmm4
+
+/* GetExp(x) */
+        vgetexppd {sae}, %zmm7, %zmm5
+
+/* DblRcp ~ 1/Mantissa */
+        vrcp14pd  %zmm6, %zmm8
+
+/* x<=0? */
+        vfpclasspd $94, %zmm7, %k0
+
+/* round DblRcp to 4 fractional bits (RN mode, no Precision exception) */
+        vrndscalepd $88, {sae}, %zmm8, %zmm3
+        vmovups   poly_coeff4+__svml_dlog2_data_internal_avx512(%rip), %zmm8
+        kmovw     %k0, %edx
+
+/* Reduced argument: R = DblRcp*Mantissa - 1 */
+        vfmsub213pd {rn-sae}, %zmm2, %zmm3, %zmm6
+        vcmppd    $17, {sae}, %zmm1, %zmm3, %k1
+        vfmadd231pd {rn-sae}, %zmm6, %zmm12, %zmm8
+        vmovups   poly_coeff2+__svml_dlog2_data_internal_avx512(%rip), %zmm12
+        vfmadd231pd {rn-sae}, %zmm6, %zmm10, %zmm0
+        vfmadd231pd {rn-sae}, %zmm6, %zmm11, %zmm14
+        vmovups   poly_coeff1+__svml_dlog2_data_internal_avx512(%rip), %zmm1
+
+/* R^2 */
+        vmulpd    {rn-sae}, %zmm6, %zmm6, %zmm15
+        vfmadd231pd {rn-sae}, %zmm6, %zmm13, %zmm12
+
+/* Prepare table index */
+        vpsrlq    $48, %zmm3, %zmm9
+
+/* add 1 to Expon if DblRcp<0.75 */
+        vaddpd    {rn-sae}, %zmm2, %zmm5, %zmm5{%k1}
+        vmulpd    {rn-sae}, %zmm15, %zmm15, %zmm13
+        vfmadd213pd {rn-sae}, %zmm14, %zmm15, %zmm0
+        vfmadd213pd {rn-sae}, %zmm12, %zmm15, %zmm8
+        vpermt2pd Log_tbl+64+__svml_dlog2_data_internal_avx512(%rip), %zmm9, %zmm4
+
+/* polynomial */
+        vfmadd213pd {rn-sae}, %zmm8, %zmm13, %zmm0
+        vfmadd213pd {rn-sae}, %zmm1, %zmm6, %zmm0
+        vfmadd213pd {rn-sae}, %zmm4, %zmm0, %zmm6
+        vaddpd    {rn-sae}, %zmm6, %zmm5, %zmm0
+        testl     %edx, %edx
+
+/* Go to special inputs processing branch */
+        jne       L(SPECIAL_VALUES_BRANCH)
+                                # LOE rbx r12 r13 r14 r15 edx zmm0 zmm7
+
+/* Restore registers
+ * and exit the function
+ */
+
+L(EXIT):
+        movq      %rbp, %rsp
+        popq      %rbp
+        cfi_def_cfa(7, 8)
+        cfi_restore(6)
+        ret
+        cfi_def_cfa(6, 16)
+        cfi_offset(6, -16)
+
+/* Branch to process
+ * special inputs
+ */
+
+L(SPECIAL_VALUES_BRANCH):
+        vmovups   %zmm7, 64(%rsp)
+        vmovups   %zmm0, 128(%rsp)
+                                # LOE rbx r12 r13 r14 r15 edx zmm0
+
+        xorl      %eax, %eax
+                                # LOE rbx r12 r13 r14 r15 eax edx
+
+        vzeroupper
+        movq      %r12, 16(%rsp)
+        /*  DW_CFA_expression: r12 (r12) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -176; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0c, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x50, 0xff, 0xff, 0xff, 0x22
+        movl      %eax, %r12d
+        movq      %r13, 8(%rsp)
+        /*  DW_CFA_expression: r13 (r13) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -184; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0d, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x48, 0xff, 0xff, 0xff, 0x22
+        movl      %edx, %r13d
+        movq      %r14, (%rsp)
+        /*  DW_CFA_expression: r14 (r14) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -192; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0e, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x40, 0xff, 0xff, 0xff, 0x22
+                                # LOE rbx r15 r12d r13d
+
+/* Range mask
+ * bits check
+ */
+
+L(RANGEMASK_CHECK):
+        btl       %r12d, %r13d
+
+/* Call scalar math function */
+        jc        L(SCALAR_MATH_CALL)
+                                # LOE rbx r15 r12d r13d
+
+/* Special inputs
+ * processing loop
+ */
+
+L(SPECIAL_VALUES_LOOP):
+        incl      %r12d
+        cmpl      $8, %r12d
+
+/* Check bits in range mask */
+        jl        L(RANGEMASK_CHECK)
+                                # LOE rbx r15 r12d r13d
+
+        movq      16(%rsp), %r12
+        cfi_restore(12)
+        movq      8(%rsp), %r13
+        cfi_restore(13)
+        movq      (%rsp), %r14
+        cfi_restore(14)
+        vmovups   128(%rsp), %zmm0
+
+/* Go to exit */
+        jmp       L(EXIT)
+        /*  DW_CFA_expression: r12 (r12) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -176; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0c, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x50, 0xff, 0xff, 0xff, 0x22
+        /*  DW_CFA_expression: r13 (r13) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -184; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0d, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x48, 0xff, 0xff, 0xff, 0x22
+        /*  DW_CFA_expression: r14 (r14) (DW_OP_lit8; DW_OP_minus; DW_OP_const4s: -64; DW_OP_and; DW_OP_const4s: -192; DW_OP_plus)  */
+        .cfi_escape 0x10, 0x0e, 0x0e, 0x38, 0x1c, 0x0d, 0xc0, 0xff, 0xff, 0xff, 0x1a, 0x0d, 0x40, 0xff, 0xff, 0xff, 0x22
+                                # LOE rbx r12 r13 r14 r15 zmm0
+
+/* Scalar math fucntion call
+ * to process special input
+ */
+
+L(SCALAR_MATH_CALL):
+        movl      %r12d, %r14d
+        movsd     64(%rsp,%r14,8), %xmm0
+        call      log2@PLT
+                                # LOE rbx r14 r15 r12d r13d xmm0
+
+        movsd     %xmm0, 128(%rsp,%r14,8)
+
+/* Process special inputs in loop */
+        jmp       L(SPECIAL_VALUES_LOOP)
+                                # LOE rbx r15 r12d r13d
+END(_ZGVeN8v_log2_skx)
+
+        .section .rodata, "a"
+        .align 64
+
+#ifdef __svml_dlog2_data_internal_avx512_typedef
+typedef unsigned int VUINT32;
+typedef struct {
+        __declspec(align(64)) VUINT32 Log_tbl[16][2];
+        __declspec(align(64)) VUINT32 One[8][2];
+        __declspec(align(64)) VUINT32 C075[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff9[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff8[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff7[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff6[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff5[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff4[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff3[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff2[8][2];
+        __declspec(align(64)) VUINT32 poly_coeff1[8][2];
+   } __svml_dlog2_data_internal_avx512;
+#endif
+__svml_dlog2_data_internal_avx512:
+        /*== Log_tbl ==*/
+        .quad 0x0000000000000000
+        .quad 0xbfb663f6fac91316
+        .quad 0xbfc5c01a39fbd688
+        .quad 0xbfcfbc16b902680a
+        .quad 0xbfd49a784bcd1b8b
+        .quad 0xbfd91bba891f1709
+        .quad 0xbfdd6753e032ea0f
+        .quad 0xbfe0c10500d63aa6
+        .quad 0x3fda8ff971810a5e
+        .quad 0x3fd6cb0f6865c8ea
+        .quad 0x3fd32bfee370ee68
+        .quad 0x3fcf5fd8a9063e35
+        .quad 0x3fc8a8980abfbd32
+        .quad 0x3fc22dadc2ab3497
+        .quad 0x3fb7d60496cfbb4c
+        .quad 0x3fa77394c9d958d5
+        /*== One ==*/
+        .align 64
+        .quad 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000, 0x3ff0000000000000
+        /*== C075 0.75 ==*/
+        .align 64
+        .quad 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000, 0x3fe8000000000000
+        /*== poly_coeff9 ==*/
+        .align 64
+        .quad 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12, 0x3fc4904bda0e1d12
+        /*== poly_coeff8 ==*/
+        .align 64
+        .quad 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce, 0xbfc71fb84deb5cce
+        /*== poly_coeff7 ==*/
+        .align 64
+        .quad 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613, 0x3fca617351818613
+        /*== poly_coeff6 ==*/
+        .align 64
+        .quad 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c, 0xbfcec707e4e3144c
+        /*== poly_coeff5 ==*/
+        .align 64
+        .quad 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a, 0x3fd2776c5114d91a
+        /*== poly_coeff4 ==*/
+        .align 64
+        .quad 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d, 0xbfd71547653d0f8d
+        /*== poly_coeff3 ==*/
+        .align 64
+        .quad 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f, 0x3fdec709dc3a029f
+        /*== poly_coeff2 ==*/
+        .align 64
+        .quad 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4, 0xbfe71547652b82d4
+        /*== poly_coeff1 ==*/
+        .align 64
+        .quad 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe, 0x3ff71547652b82fe
+        .align 64
+        .type	__svml_dlog2_data_internal_avx512,@object
+        .size	__svml_dlog2_data_internal_avx512,.-__svml_dlog2_data_internal_avx512