RC4 tune-up for AMD64. Performance improvement of 2.22x is measured for

linux-x86_64 target.

crypto/rc4/asm/rc4-amd64.pl

+#!/usr/bin/env perl
+#
+# ====================================================================
+# Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
+# project. Rights for redistribution and usage in source and binary
+# forms are granted according to the OpenSSL license.
+# ====================================================================
+#
+# 2.22x RC4 tune-up:-) It should be noted though that my hand [as in
+# "hand-coded assembler"] doesn't stand for the whole improvement
+# coefficient. It turned out that eliminating RC4_CHAR from config
+# line results in ~40% improvement (yes, even for C implementation).
+# Presumably it has everything to do with AMD cache architecture and
+# RAW or whatever penalties. Once again! The module *requires* config
+# line *without* RC4_CHAR! As for coding "secret," I bet on partial
+# register arithmetics. For example instead 'inc %r8; and $255,%r8'
+# I simply 'inc %r8b'. Even though optimization manual discourages
+# to operate on partial registers, it turned out to be the best bet.
+# At least for AMD... How IA32E would perform remains to be seen...
+
+$output=shift;
+
+$win64=1 if ($output =~ /win64.[s|asm]/);
+
+open STDOUT,">$output" || die "can't open $output: $!";
+
+if (defined($win64)) {
+    $dat="%rcx";	# arg1
+    $len="%rdx";	# arg2
+    $inp="%rsi";	# r8, arg3 moves here
+    $out="%rdi";	# r9, arg4 moves here
+} else {
+    $dat="%rdi";	# arg1
+    $len="%rsi";	# arg2
+    $inp="%rdx";	# arg3
+    $out="%rcx";	# arg4
+}
+
+$XX="%r10";
+$TX="%r8";
+$YY="%r11";
+$TY="%r9";
+
+sub PTR() {
+    my $ret=shift;
+    if (defined($win64)) {
+	$ret =~ s/\[([\S]+)\+([\S]+)\]/[$2+$1]/g; # [%rN+%rM*4]->[%rM*4+%rN]
+    } else {
+	$ret =~ s/[\+\*]/,/g;		# [%rN+%rM*4]->[%rN,%rM,4]
+	$ret =~ s/\[([^\]]+)\]/($1)/g;	# [%rN]->(%rN)
+    }
+    $ret;
+}
+
+$code=<<___ if (!defined($win64));
+.text
+
+.globl	RC4
+.type	RC4,\@function
+.align	16
+RC4:	or	$len,$len
+	jne	.Lentry
+	.byte	0xF3,0xC3	# repz ret, 2-byte ret
+.Lentry:
+___
+$code=<<___ if (defined($win64));
+TEXT	SEGMENT
+PUBLIC	RC4
+ALIGN	16
+RC4	PROC NEAR
+	or	$len,$len
+	jne	.Lentry
+	DB	F3h,C3h		; repz ret, 2-byte ret
+.Lentry:
+	push	%edi
+	push	%esi
+	sub	\$40,%esp
+	mov	%r8,$inp
+	mov	%r9,$out
+___
+$code.=<<___;
+	add	\$8,$dat
+	movl	`&PTR("DWORD-8[$dat]")`,$XX#d
+	movl	`&PTR("DWORD-4[$dat]")`,$YY#d
+	test	\$-8,$len
+	jz	.Lloop1
+.align	16
+.Lloop8:
+	movq	`&PTR("QWORD[$inp]")`,%rax
+
+	inc	$XX#b
+	movl	`&PTR("DWORD[$dat+$XX*4]")`,$TX#d
+	add	$TX#b,$YY#b
+	movl	`&PTR("DWORD[$dat+$YY*4]")`,$TY#d
+	movl	$TX#d,`&PTR("DWORD[$dat+$YY*4]")`
+	movl	$TY#d,`&PTR("DWORD[$dat+$XX*4]")`
+	add	$TY#b,$TX#b
+	inc	$XX#b
+	movl	`&PTR("DWORD[$dat+$TX*4]")`,$TY#d
+	xor	$TY,%rax
+___
+for ($i=1;$i<=6;$i++) {
+$code.=<<___;
+	movl	`&PTR("DWORD[$dat+$XX*4]")`,$TX#d
+	add	$TX#b,$YY#b
+	movl	`&PTR("DWORD[$dat+$YY*4]")`,$TY#d
+	movl	$TX#d,`&PTR("DWORD[$dat+$YY*4]")`
+	movl	$TY#d,`&PTR("DWORD[$dat+$XX*4]")`
+	add	$TY#b,$TX#b
+	movl	`&PTR("DWORD[$dat+$TX*4]")`,$TY#d
+	shl	\$`8*$i`,$TY
+	inc	$XX#b
+	xor	$TY,%rax
+___
+}
+$code.=<<___;
+	movl	`&PTR("DWORD[$dat+$XX*4]")`,$TX#d
+	add	$TX#b,$YY#b
+	movl	`&PTR("DWORD[$dat+$YY*4]")`,$TY#d
+	movl	$TX#d,`&PTR("DWORD[$dat+$YY*4]")`
+	movl	$TY#d,`&PTR("DWORD[$dat+$XX*4]")`
+	sub	\$8,$len
+	add	$TY#b,$TX#b
+	add	\$8,$out
+	movl	`&PTR("DWORD[$dat+$TX*4]")`,$TY#d
+	shl	\$56,$TY
+	add	\$8,$inp
+	xor	$TY,%rax
+
+	mov	%rax,`&PTR("QWORD-8[$out]")`
+
+	test	\$-8,$len
+	jnz	.Lloop8
+	cmp	\$0,$len
+	jne	.Lloop1
+.Lexit:
+	movl	$XX#d,`&PTR("DWORD-8[$dat]")`
+	movl	$YY#d,`&PTR("DWORD-4[$dat]")`
+___
+$code.=<<___ if (defined($win64));
+	add	\$40,%esp
+	pop	%esi
+	pop	%edi
+	DB	F3h,C3h		; retz ret, 2-byte ret
+___
+$code.=<<___ if (!defined($win64));
+	.byte	0xF3,0xC3	# repz ret, 2-byte ret
+___
+$code.=<<___;
+.align	16
+.Lloop1:
+	movzb	`&PTR("BYTE[$inp]")`,%rax
+	inc	$XX#b
+	nop
+	movl	`&PTR("DWORD[$dat+$XX*4]")`,$TX#d
+	add	$TX#b,$YY#b
+	movl	`&PTR("DWORD[$dat+$YY*4]")`,$TY#d
+	movl	$TX#d,`&PTR("DWORD[$dat+$YY*4]")`
+	movl	$TY#d,`&PTR("DWORD[$dat+$XX*4]")`
+	add	$TY#b,$TX#b
+	movl	`&PTR("DWORD[$dat+$TX*4]")`,$TY#d
+	xor	$TY,%rax
+	inc	$inp
+	movb	%al,`&PTR("BYTE[$out]")`
+	inc	$out
+	dec	$len
+	jnz	.Lloop1
+	jmp	.Lexit
+___
+if (defined($win64)) {
+    $code.="RC4	ENDP\n";
+} else {
+    $code.=".size	RC4,.-RC4\n"
+}
+
+$code =~ s/#([bwd])/$1/gm;
+$code =~ s/\`([^\`]*)\`/eval $1/gem;
+
+if (defined($win64)) {
+    $code =~ s/\.align/ALIGN/gm;
+    $code =~ s/[\$%]//gm;
+    $code =~ s/\.L/\$L/gm;
+    $code =~ s/([\w]+)([\s]+)([\S]+),([\S]+)/$1$2$4,$3/gm;
+    $code =~ s/([QD]*WORD|BYTE)/$1 PTR /gm;
+    $code =~ s/(mov[z]*)[bwlq]/$1/gm;
+} else {
+    $code =~ s/[QD]*WORD|BYTE//gm;
+}
+print $code;