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, 223 insertions, 0 deletions

diff --git a/sysdeps/x86_64/fpu/multiarch/svml_s_log2f4_core_sse4.S b/sysdeps/x86_64/fpu/multiarch/svml_s_log2f4_core_sse4.S
new file mode 100644
index 0000000000..a45ea919f4
--- /dev/null
+++ b/sysdeps/x86_64/fpu/multiarch/svml_s_log2f4_core_sse4.S
@@ -0,0 +1,223 @@
+/* Function log2f vectorized with SSE4.
+   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_slog2_data_internal
+ */
+#define MinNorm                       	0
+#define MaxNorm                       	16
+#define iBrkValue                     	32
+#define iOffExpoMask                  	48
+#define One                           	64
+#define sPoly                         	80
+
+#include <sysdep.h>
+
+        .text
+	.section .text.sse4,"ax",@progbits
+ENTRY(_ZGVbN4v_log2f_sse4)
+        subq      $72, %rsp
+        cfi_def_cfa_offset(80)
+        movaps    %xmm0, %xmm1
+
+/* reduction: compute r,n */
+        movdqu    iBrkValue+__svml_slog2_data_internal(%rip), %xmm2
+        movaps    %xmm0, %xmm4
+        movdqu    iOffExpoMask+__svml_slog2_data_internal(%rip), %xmm10
+        psubd     %xmm2, %xmm1
+        pand      %xmm1, %xmm10
+        movaps    %xmm0, %xmm3
+        paddd     %xmm2, %xmm10
+        psrad     $23, %xmm1
+        movups    sPoly+__svml_slog2_data_internal(%rip), %xmm5
+        movups    sPoly+32+__svml_slog2_data_internal(%rip), %xmm6
+        movups    sPoly+64+__svml_slog2_data_internal(%rip), %xmm7
+        movups    sPoly+96+__svml_slog2_data_internal(%rip), %xmm9
+        cmpltps   MinNorm+__svml_slog2_data_internal(%rip), %xmm4
+        cmpnleps  MaxNorm+__svml_slog2_data_internal(%rip), %xmm3
+        cvtdq2ps  %xmm1, %xmm1
+        subps     One+__svml_slog2_data_internal(%rip), %xmm10
+        mulps     %xmm10, %xmm5
+        movaps    %xmm10, %xmm8
+        mulps     %xmm10, %xmm6
+        mulps     %xmm10, %xmm8
+        addps     sPoly+16+__svml_slog2_data_internal(%rip), %xmm5
+        mulps     %xmm10, %xmm7
+        addps     sPoly+48+__svml_slog2_data_internal(%rip), %xmm6
+        mulps     %xmm10, %xmm9
+        mulps     %xmm8, %xmm5
+        addps     sPoly+80+__svml_slog2_data_internal(%rip), %xmm7
+        addps     sPoly+112+__svml_slog2_data_internal(%rip), %xmm9
+        addps     %xmm5, %xmm6
+        mulps     %xmm8, %xmm6
+        orps      %xmm3, %xmm4
+
+/* combine and get argument value range mask */
+        movmskps  %xmm4, %edx
+        addps     %xmm6, %xmm7
+        mulps     %xmm7, %xmm8
+        addps     %xmm8, %xmm9
+        mulps     %xmm10, %xmm9
+        addps     sPoly+128+__svml_slog2_data_internal(%rip), %xmm9
+        mulps     %xmm9, %xmm10
+        addps     %xmm10, %xmm1
+        testl     %edx, %edx
+
+/* Go to special inputs processing branch */
+        jne       L(SPECIAL_VALUES_BRANCH)
+                                # LOE rbx rbp r12 r13 r14 r15 edx xmm0 xmm1
+
+/* Restore registers
+ * and exit the function
+ */
+
+L(EXIT):
+        movaps    %xmm1, %xmm0
+        addq      $72, %rsp
+        cfi_def_cfa_offset(8)
+        ret
+        cfi_def_cfa_offset(80)
+
+/* Branch to process
+ * special inputs
+ */
+
+L(SPECIAL_VALUES_BRANCH):
+        movups    %xmm0, 32(%rsp)
+        movups    %xmm1, 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
+ */
+
+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), %xmm1
+
+/* 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 xmm1
+
+/* Scalar math fucntion call
+ * to process special input
+ */
+
+L(SCALAR_MATH_CALL):
+        movl      %r12d, %r14d
+        movss     32(%rsp,%r14,4), %xmm0
+        call      log2f@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
+END(_ZGVbN4v_log2f_sse4)
+
+        .section .rodata, "a"
+        .align 16
+
+#ifdef __svml_slog2_data_internal_typedef
+typedef unsigned int VUINT32;
+typedef struct {
+        __declspec(align(16)) VUINT32 MinNorm[4][1];
+        __declspec(align(16)) VUINT32 MaxNorm[4][1];
+        __declspec(align(16)) VUINT32 iBrkValue[4][1];
+        __declspec(align(16)) VUINT32 iOffExpoMask[4][1];
+        __declspec(align(16)) VUINT32 One[4][1];
+        __declspec(align(16)) VUINT32 sPoly[9][4][1];
+} __svml_slog2_data_internal;
+#endif
+__svml_slog2_data_internal:
+        /*== MinNorm ==*/
+        .long 0x00800000, 0x00800000, 0x00800000, 0x00800000
+        /*== MaxNorm ==*/
+        .align 16
+        .long 0x7f7fffff, 0x7f7fffff, 0x7f7fffff, 0x7f7fffff
+        /*== iBrkValue = SP 2/3 ==*/
+        .align 16
+        .long 0x3f2aaaab, 0x3f2aaaab, 0x3f2aaaab, 0x3f2aaaab
+        /*== iOffExpoMask = SP significand mask ==*/
+        .align 16
+        .long 0x007fffff, 0x007fffff, 0x007fffff, 0x007fffff
+        /*== sOne = SP 1.0 ==*/
+        .align 16
+        .long 0x3f800000, 0x3f800000, 0x3f800000, 0x3f800000
+        /*== spoly[9] ==*/
+        .align 16
+        .long 0x3e554012, 0x3e554012, 0x3e554012, 0x3e554012 /* coeff9 */
+        .long 0xbe638E14, 0xbe638E14, 0xbe638E14, 0xbe638E14 /* coeff8 */
+        .long 0x3e4D660B, 0x3e4D660B, 0x3e4D660B, 0x3e4D660B /* coeff7 */
+        .long 0xbe727824, 0xbe727824, 0xbe727824, 0xbe727824 /* coeff6 */
+        .long 0x3e93DD07, 0x3e93DD07, 0x3e93DD07, 0x3e93DD07 /* coeff5 */
+        .long 0xbeB8B969, 0xbeB8B969, 0xbeB8B969, 0xbeB8B969 /* coeff4 */
+        .long 0x3eF637C0, 0x3eF637C0, 0x3eF637C0, 0x3eF637C0 /* coeff3 */
+        .long 0xbf38AA2B, 0xbf38AA2B, 0xbf38AA2B, 0xbf38AA2B /* coeff2 */
+        .long 0x3fB8AA3B, 0x3fB8AA3B, 0x3fB8AA3B, 0x3fB8AA3B /* coeff1 */
+        .align 16
+        .type	__svml_slog2_data_internal,@object
+        .size	__svml_slog2_data_internal,.-__svml_slog2_data_internal