comparison src/zlib-1.2.8/contrib/amd64/amd64-match.S @ 43:5ea0608b923f

Current zlib source

+/*
+ * match.S -- optimized version of longest_match()
+ * based on the similar work by Gilles Vollant, and Brian Raiter, written 1998
+ *
+ * This is free software; you can redistribute it and/or modify it
+ * under the terms of the BSD License. Use by owners of Che Guevarra
+ * parafernalia is prohibited, where possible, and highly discouraged
+ * elsewhere.
+ */
+
+#ifndef NO_UNDERLINE
+#	define	match_init	_match_init
+#	define	longest_match	_longest_match
+#endif
+
+#define	scanend		ebx
+#define	scanendw	bx
+#define	chainlenwmask	edx /* high word: current chain len low word: s->wmask */
+#define	curmatch	rsi
+#define	curmatchd	esi
+#define	windowbestlen	r8
+#define	scanalign	r9
+#define	scanalignd	r9d
+#define	window		r10
+#define	bestlen		r11
+#define	bestlend	r11d
+#define	scanstart	r12d
+#define	scanstartw	r12w
+#define scan		r13
+#define nicematch	r14d
+#define	limit		r15
+#define	limitd		r15d
+#define prev		rcx
+
+/*
+ * The 258 is a "magic number, not a parameter -- changing it
+ * breaks the hell loose
+ */
+#define	MAX_MATCH	(258)
+#define	MIN_MATCH	(3)
+#define	MIN_LOOKAHEAD	(MAX_MATCH + MIN_MATCH + 1)
+#define	MAX_MATCH_8	((MAX_MATCH + 7) & ~7)
+
+/* stack frame offsets */
+#define	LocalVarsSize	(112)
+#define _chainlenwmask	( 8-LocalVarsSize)(%rsp)
+#define _windowbestlen	(16-LocalVarsSize)(%rsp)
+#define save_r14        (24-LocalVarsSize)(%rsp)
+#define save_rsi        (32-LocalVarsSize)(%rsp)
+#define save_rbx        (40-LocalVarsSize)(%rsp)
+#define save_r12        (56-LocalVarsSize)(%rsp)
+#define save_r13        (64-LocalVarsSize)(%rsp)
+#define save_r15        (80-LocalVarsSize)(%rsp)
+
+
+.globl	match_init, longest_match
+
+/*
+ * On AMD64 the first argument of a function (in our case -- the pointer to
+ * deflate_state structure) is passed in %rdi, hence our offsets below are
+ * all off of that.
+ */
+
+/* you can check the structure offset by running
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "deflate.h"
+
+void print_depl()
+{
+deflate_state ds;
+deflate_state *s=&ds;
+printf("size pointer=%u\n",(int)sizeof(void*));
+
+printf("#define dsWSize         (%3u)(%%rdi)\n",(int)(((char*)&(s->w_size))-((char*)s)));
+printf("#define dsWMask         (%3u)(%%rdi)\n",(int)(((char*)&(s->w_mask))-((char*)s)));
+printf("#define dsWindow        (%3u)(%%rdi)\n",(int)(((char*)&(s->window))-((char*)s)));
+printf("#define dsPrev          (%3u)(%%rdi)\n",(int)(((char*)&(s->prev))-((char*)s)));
+printf("#define dsMatchLen      (%3u)(%%rdi)\n",(int)(((char*)&(s->match_length))-((char*)s)));
+printf("#define dsPrevMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_match))-((char*)s)));
+printf("#define dsStrStart      (%3u)(%%rdi)\n",(int)(((char*)&(s->strstart))-((char*)s)));
+printf("#define dsMatchStart    (%3u)(%%rdi)\n",(int)(((char*)&(s->match_start))-((char*)s)));
+printf("#define dsLookahead     (%3u)(%%rdi)\n",(int)(((char*)&(s->lookahead))-((char*)s)));
+printf("#define dsPrevLen       (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_length))-((char*)s)));
+printf("#define dsMaxChainLen   (%3u)(%%rdi)\n",(int)(((char*)&(s->max_chain_length))-((char*)s)));
+printf("#define dsGoodMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->good_match))-((char*)s)));
+printf("#define dsNiceMatch     (%3u)(%%rdi)\n",(int)(((char*)&(s->nice_match))-((char*)s)));
+}
+
+*/
+
+
+/*
+  to compile for XCode 3.2 on MacOSX x86_64
+  - run "gcc -g -c -DXCODE_MAC_X64_STRUCTURE amd64-match.S"
+ */
+
+
+#ifndef CURRENT_LINX_XCODE_MAC_X64_STRUCTURE
+#define dsWSize		( 68)(%rdi)
+#define dsWMask		( 76)(%rdi)
+#define dsWindow	( 80)(%rdi)
+#define dsPrev		( 96)(%rdi)
+#define dsMatchLen	(144)(%rdi)
+#define dsPrevMatch	(148)(%rdi)
+#define dsStrStart	(156)(%rdi)
+#define dsMatchStart	(160)(%rdi)
+#define dsLookahead	(164)(%rdi)
+#define dsPrevLen	(168)(%rdi)
+#define dsMaxChainLen	(172)(%rdi)
+#define dsGoodMatch	(188)(%rdi)
+#define dsNiceMatch	(192)(%rdi)
+
+#else 
+
+#ifndef STRUCT_OFFSET
+#	define STRUCT_OFFSET	(0)
+#endif
+
+
+#define dsWSize		( 56 + STRUCT_OFFSET)(%rdi)
+#define dsWMask		( 64 + STRUCT_OFFSET)(%rdi)
+#define dsWindow	( 72 + STRUCT_OFFSET)(%rdi)
+#define dsPrev		( 88 + STRUCT_OFFSET)(%rdi)
+#define dsMatchLen	(136 + STRUCT_OFFSET)(%rdi)
+#define dsPrevMatch	(140 + STRUCT_OFFSET)(%rdi)
+#define dsStrStart	(148 + STRUCT_OFFSET)(%rdi)
+#define dsMatchStart	(152 + STRUCT_OFFSET)(%rdi)
+#define dsLookahead	(156 + STRUCT_OFFSET)(%rdi)
+#define dsPrevLen	(160 + STRUCT_OFFSET)(%rdi)
+#define dsMaxChainLen	(164 + STRUCT_OFFSET)(%rdi)
+#define dsGoodMatch	(180 + STRUCT_OFFSET)(%rdi)
+#define dsNiceMatch	(184 + STRUCT_OFFSET)(%rdi)
+
+#endif
+
+
+
+
+.text
+
+/* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */
+
+longest_match:
+/*
+ * Retrieve the function arguments. %curmatch will hold cur_match
+ * throughout the entire function (passed via rsi on amd64).
+ * rdi will hold the pointer to the deflate_state (first arg on amd64)
+ */
+		mov     %rsi, save_rsi
+		mov     %rbx, save_rbx
+		mov	%r12, save_r12
+		mov     %r13, save_r13
+		mov     %r14, save_r14
+		mov     %r15, save_r15
+
+/* uInt wmask = s->w_mask;						*/
+/* unsigned chain_length = s->max_chain_length;				*/
+/* if (s->prev_length >= s->good_match) {				*/
+/*     chain_length >>= 2;						*/
+/* }									*/
+
+		movl	dsPrevLen, %eax
+		movl	dsGoodMatch, %ebx
+		cmpl	%ebx, %eax
+		movl	dsWMask, %eax
+		movl	dsMaxChainLen, %chainlenwmask
+		jl	LastMatchGood
+		shrl	$2, %chainlenwmask
+LastMatchGood:
+
+/* chainlen is decremented once beforehand so that the function can	*/
+/* use the sign flag instead of the zero flag for the exit test.	*/
+/* It is then shifted into the high word, to make room for the wmask	*/
+/* value, which it will always accompany.				*/
+
+		decl	%chainlenwmask
+		shll	$16, %chainlenwmask
+		orl	%eax, %chainlenwmask
+
+/* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;	*/
+
+		movl	dsNiceMatch, %eax
+		movl	dsLookahead, %ebx
+		cmpl	%eax, %ebx
+		jl	LookaheadLess
+		movl	%eax, %ebx
+LookaheadLess:	movl	%ebx, %nicematch
+
+/* register Bytef *scan = s->window + s->strstart;			*/
+
+		mov	dsWindow, %window
+		movl	dsStrStart, %limitd
+		lea	(%limit, %window), %scan
+
+/* Determine how many bytes the scan ptr is off from being		*/
+/* dword-aligned.							*/
+
+		mov	%scan, %scanalign
+		negl	%scanalignd
+		andl	$3, %scanalignd
+
+/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ?			*/
+/*     s->strstart - (IPos)MAX_DIST(s) : NIL;				*/
+
+		movl	dsWSize, %eax
+		subl	$MIN_LOOKAHEAD, %eax
+		xorl	%ecx, %ecx
+		subl	%eax, %limitd
+		cmovng	%ecx, %limitd
+
+/* int best_len = s->prev_length;					*/
+
+		movl	dsPrevLen, %bestlend
+
+/* Store the sum of s->window + best_len in %windowbestlen locally, and in memory.	*/
+
+		lea	(%window, %bestlen), %windowbestlen
+		mov	%windowbestlen, _windowbestlen
+
+/* register ush scan_start = *(ushf*)scan;				*/
+/* register ush scan_end   = *(ushf*)(scan+best_len-1);			*/
+/* Posf *prev = s->prev;						*/
+
+		movzwl	(%scan), %scanstart
+		movzwl	-1(%scan, %bestlen), %scanend
+		mov	dsPrev, %prev
+
+/* Jump into the main loop.						*/
+
+		movl	%chainlenwmask, _chainlenwmask
+		jmp	LoopEntry
+
+.balign 16
+
+/* do {
+ *     match = s->window + cur_match;
+ *     if (*(ushf*)(match+best_len-1) != scan_end ||
+ *         *(ushf*)match != scan_start) continue;
+ *     [...]
+ * } while ((cur_match = prev[cur_match & wmask]) > limit
+ *          && --chain_length != 0);
+ *
+ * Here is the inner loop of the function. The function will spend the
+ * majority of its time in this loop, and majority of that time will
+ * be spent in the first ten instructions.
+ */
+LookupLoop:
+		andl	%chainlenwmask, %curmatchd
+		movzwl	(%prev, %curmatch, 2), %curmatchd
+		cmpl	%limitd, %curmatchd
+		jbe	LeaveNow
+		subl	$0x00010000, %chainlenwmask
+		js	LeaveNow
+LoopEntry:	cmpw	-1(%windowbestlen, %curmatch), %scanendw
+		jne	LookupLoop
+		cmpw	%scanstartw, (%window, %curmatch)
+		jne	LookupLoop
+
+/* Store the current value of chainlen.					*/
+		movl	%chainlenwmask, _chainlenwmask
+
+/* %scan is the string under scrutiny, and %prev to the string we	*/
+/* are hoping to match it up with. In actuality, %esi and %edi are	*/
+/* both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and %edx is	*/
+/* initialized to -(MAX_MATCH_8 - scanalign).				*/
+
+		mov	$(-MAX_MATCH_8), %rdx
+		lea	(%curmatch, %window), %windowbestlen
+		lea	MAX_MATCH_8(%windowbestlen, %scanalign), %windowbestlen
+		lea	MAX_MATCH_8(%scan, %scanalign), %prev
+
+/* the prefetching below makes very little difference... */
+		prefetcht1	(%windowbestlen, %rdx)
+		prefetcht1	(%prev, %rdx)
+
+/*
+ * Test the strings for equality, 8 bytes at a time. At the end,
+ * adjust %rdx so that it is offset to the exact byte that mismatched.
+ *
+ * It should be confessed that this loop usually does not represent
+ * much of the total running time. Replacing it with a more
+ * straightforward "rep cmpsb" would not drastically degrade
+ * performance -- unrolling it, for example, makes no difference.
+ */
+
+#undef USE_SSE	/* works, but is 6-7% slower, than non-SSE... */
+
+LoopCmps:
+#ifdef USE_SSE
+		/* Preload the SSE registers */
+		movdqu	  (%windowbestlen, %rdx), %xmm1
+		movdqu	  (%prev, %rdx), %xmm2
+		pcmpeqb	%xmm2, %xmm1
+		movdqu	16(%windowbestlen, %rdx), %xmm3
+		movdqu	16(%prev, %rdx), %xmm4
+		pcmpeqb	%xmm4, %xmm3
+		movdqu	32(%windowbestlen, %rdx), %xmm5
+		movdqu	32(%prev, %rdx), %xmm6
+		pcmpeqb	%xmm6, %xmm5
+		movdqu	48(%windowbestlen, %rdx), %xmm7
+		movdqu	48(%prev, %rdx), %xmm8
+		pcmpeqb	%xmm8, %xmm7
+
+		/* Check the comparisions' results */
+		pmovmskb %xmm1, %rax
+		notw	%ax
+		bsfw	%ax, %ax
+		jnz	LeaveLoopCmps
+		
+		/* this is the only iteration of the loop with a possibility of having
+		   incremented rdx by 0x108 (each loop iteration add 16*4 = 0x40 
+		   and (0x40*4)+8=0x108 */
+		add	$8, %rdx
+		jz LenMaximum
+		add	$8, %rdx
+
+		
+		pmovmskb %xmm3, %rax
+		notw	%ax
+		bsfw	%ax, %ax
+		jnz	LeaveLoopCmps
+		
+		
+		add	$16, %rdx
+
+
+		pmovmskb %xmm5, %rax
+		notw	%ax
+		bsfw	%ax, %ax
+		jnz	LeaveLoopCmps
+		
+		add	$16, %rdx
+
+
+		pmovmskb %xmm7, %rax
+		notw	%ax
+		bsfw	%ax, %ax
+		jnz	LeaveLoopCmps
+		
+		add	$16, %rdx
+		
+		jmp	LoopCmps
+LeaveLoopCmps:	add	%rax, %rdx
+#else
+		mov	(%windowbestlen, %rdx), %rax
+		xor	(%prev, %rdx), %rax
+		jnz	LeaveLoopCmps
+		
+		mov	8(%windowbestlen, %rdx), %rax
+		xor	8(%prev, %rdx), %rax
+		jnz	LeaveLoopCmps8
+
+		mov	16(%windowbestlen, %rdx), %rax
+		xor	16(%prev, %rdx), %rax
+		jnz	LeaveLoopCmps16
+				
+		add	$24, %rdx
+		jnz	LoopCmps
+		jmp	LenMaximum
+#	if 0
+/*
+ * This three-liner is tantalizingly simple, but bsf is a slow instruction,
+ * and the complicated alternative down below is quite a bit faster. Sad...
+ */
+
+LeaveLoopCmps:	bsf	%rax, %rax /* find the first non-zero bit */
+		shrl	$3, %eax /* divide by 8 to get the byte */
+		add	%rax, %rdx
+#	else
+LeaveLoopCmps16:
+		add	$8, %rdx
+LeaveLoopCmps8:
+		add	$8, %rdx
+LeaveLoopCmps:	testl   $0xFFFFFFFF, %eax /* Check the first 4 bytes */
+		jnz     Check16
+		add     $4, %rdx
+		shr     $32, %rax
+Check16:        testw   $0xFFFF, %ax
+		jnz     LenLower
+		add	$2, %rdx
+		shrl	$16, %eax
+LenLower:	subb	$1, %al
+		adc	$0, %rdx
+#	endif
+#endif
+
+/* Calculate the length of the match. If it is longer than MAX_MATCH,	*/
+/* then automatically accept it as the best possible match and leave.	*/
+
+		lea	(%prev, %rdx), %rax
+		sub	%scan, %rax
+		cmpl	$MAX_MATCH, %eax
+		jge	LenMaximum
+
+/* If the length of the match is not longer than the best match we	*/
+/* have so far, then forget it and return to the lookup loop.		*/
+
+		cmpl	%bestlend, %eax
+		jg	LongerMatch
+		mov	_windowbestlen, %windowbestlen
+		mov	dsPrev, %prev
+		movl	_chainlenwmask, %edx
+		jmp	LookupLoop
+
+/*         s->match_start = cur_match;					*/
+/*         best_len = len;						*/
+/*         if (len >= nice_match) break;				*/
+/*         scan_end = *(ushf*)(scan+best_len-1);			*/
+
+LongerMatch:
+		movl	%eax, %bestlend
+		movl	%curmatchd, dsMatchStart
+		cmpl	%nicematch, %eax
+		jge	LeaveNow
+
+		lea	(%window, %bestlen), %windowbestlen
+		mov	%windowbestlen, _windowbestlen
+
+		movzwl	-1(%scan, %rax), %scanend
+		mov	dsPrev, %prev
+		movl	_chainlenwmask, %chainlenwmask
+		jmp	LookupLoop
+
+/* Accept the current string, with the maximum possible length.		*/
+
+LenMaximum:
+		movl	$MAX_MATCH, %bestlend
+		movl	%curmatchd, dsMatchStart
+
+/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len;		*/
+/* return s->lookahead;							*/
+
+LeaveNow:
+		movl	dsLookahead, %eax
+		cmpl	%eax, %bestlend
+		cmovngl	%bestlend, %eax
+LookaheadRet:
+
+/* Restore the registers and return from whence we came.			*/
+
+	mov	save_rsi, %rsi
+	mov	save_rbx, %rbx
+	mov	save_r12, %r12
+	mov	save_r13, %r13
+	mov	save_r14, %r14
+	mov	save_r15, %r15
+
+	ret
+
+match_init:	ret