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openssl/crypto/bn/asm/x86-mont.pl
Andy Polyakov 48d2335d73 Non-SSE2 path to bn_mul_mont. But it's disabled, because it currently 
doesn't give performance improvement.
2006-11-27 14:59:35 +00:00

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#!/usr/bin/env perl
# ====================================================================
# Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
# project. The module is, however, dual licensed under OpenSSL and
# CRYPTOGAMS licenses depending on where you obtain it. For further
# details see http://www.openssl.org/~appro/cryptogams/.
# ====================================================================
# October 2005
#
# This is a "teaser" code, as it can be improved in several ways...
# First of all non-SSE2 path should be implemented (yes, for now it
# performs Montgomery multiplication/convolution only on SSE2-capable
# CPUs such as P4, others fall down to original code). Then inner loop
# can be unrolled and modulo-scheduled to improve ILP and possibly
# moved to 128-bit XMM register bank (though it would require input
# rearrangement and/or increase bus bandwidth utilization). Dedicated
# squaring procedure should give further performance improvement...
# Yet, for being draft, the code improves rsa512 *sign* benchmark by
# 110%(!), rsa1024 one - by 70% and rsa4096 - by 20%:-)
push(@INC,"perlasm","../../perlasm");
require "x86asm.pl";
&asm_init($ARGV[0],$0);
$sse2=0;
for (@ARGV) { $sse2=1 if (/-DOPENSSL_IA32_SSE2/); }
&external_label("OPENSSL_ia32cap_P") if ($sse2);
&function_begin("bn_mul_mont",$sse2?"EXTRN\t_OPENSSL_ia32cap_P:DWORD":"");
$i="edx";
$j="ecx";
$ap="esi";
$rp="edi"; $bp="edi"; # overlapping variables!!!
$np="ebp";
$num="ebx";
$_rp=&DWP(4*0,"esp"); # stack top layout
$_ap=&DWP(4*1,"esp");
$_bp=&DWP(4*2,"esp");
$_np=&DWP(4*3,"esp");
$_n0=&DWP(4*4,"esp");
$_num=&DWP(4*5,"esp");
$_sp=&DWP(4*6,"esp");
$_bpend=&DWP(4*7,"esp");
$frame=32; # size of above frame rounded up to 16n
&xor ("eax","eax");
&mov ("edi",&wparam(5)); # int num
&cmp ("edi",3);
&jb (&label("just_leave"));
################################# load argument block...
&mov ("eax",&wparam(0)); # BN_ULONG *rp
&mov ("ebx",&wparam(1)); # const BN_ULONG *ap
&mov ("ecx",&wparam(2)); # const BN_ULONG *bp
&mov ("edx",&wparam(3)); # const BN_ULONG *np
&mov ("esi",&wparam(4)); # const BN_ULONG *n0
#&mov ("edi",&wparam(5)); # int num
&mov ("ebp","esp"); # saved stack pointer!
&add ("edi",2); # extra two words on top of tp
&neg ("edi");
&lea ("esp",&DWP(-$frame,"esp","edi",4)); # alloca($frame+4*(num+2))
&neg ("edi");
&and ("esp",-4096); # minimize TLB utilization
&mov ("esi",&DWP(0,"esi")); # pull n0[0]
&mov ($_rp,"eax"); # ... save a copy of argument block
&mov ($_ap,"ebx");
&mov ($_bp,"ecx");
&mov ($_np,"edx");
&mov ($_n0,"esi");
&lea ($num,&DWP(-2,"edi")); # num is restored to its original value
#&mov ($_num,$num); # redundant as $num is not reused
&mov ($_sp,"ebp"); # saved stack pointer!
if($sse2) {
$acc0="mm0"; # mmx register bank layout
$acc1="mm1";
$car0="mm2";
$car1="mm3";
$mul0="mm4";
$mul1="mm5";
$temp="mm6";
$mask="mm7";
&picmeup("eax","OPENSSL_ia32cap_P");
&bt (&DWP(0,"eax"),26);
&jnc (&label("non_sse2"));
&mov ("eax",-1);
&movd ($mask,"eax"); # mask 32 lower bits
&mov ($ap,$_ap); # load input pointers
&mov ($bp,$_bp);
&mov ($np,$_np);
&xor ($i,$i); # i=0
&xor ($j,$j); # j=0
&movd ($mul0,&DWP(0,$bp)); # bp[0]
&movd ($mul1,&DWP(0,$ap)); # ap[0]
&movd ($car1,&DWP(0,$np)); # np[0]
&pmuludq($mul1,$mul0); # ap[0]*bp[0]
&movq ($car0,$mul1);
&movq ($acc0,$mul1); # I wish movd worked for
&pand ($acc0,$mask); # inter-register transfers
&pmuludq($mul1,$_n0); # *=n0
&pmuludq($car1,$mul1); # "t[0]"*np[0]*n0
&paddq ($car1,$acc0);
&psrlq ($car0,32);
&psrlq ($car1,32);
&inc ($j); # j++
&set_label("1st");
&movd ($acc0,&DWP(0,$ap,$j,4)); # ap[j]
&movd ($acc1,&DWP(0,$np,$j,4)); # np[j]
&pmuludq($acc0,$mul0); # ap[j]*bp[0]
&pmuludq($acc1,$mul1); # np[j]*m1
&paddq ($car0,$acc0); # +=c0
&movq ($acc0,$car0);
&pand ($acc0,$mask);
&paddq ($car1,$acc1); # +=c1
&paddq ($car1,$acc0); # +=ap[j]*bp[0];
&movd (&DWP($frame-4,"esp",$j,4),$car1); # tp[j-1]=
&psrlq ($car0,32);
&psrlq ($car1,32);
&lea ($j,&DWP(1,$j));
&cmp ($j,$num);
&jl (&label("1st"));
&paddq ($car1,$car0);
&movq (&DWP($frame-4,"esp",$num,4),$car1);
&inc ($i); # i++
&set_label("outer");
&xor ($j,$j); # j=0
&movd ($mul0,&DWP(0,$bp,$i,4)); # bp[i]
&movd ($mul1,&DWP(0,$ap)); # ap[0]
&movd ($temp,&DWP($frame,"esp")); # tp[0]
&movd ($car1,&DWP(0,$np)); # np[0]
&pmuludq($mul1,$mul0); # ap[0]*bp[i]
&paddq ($mul1,$temp); # +=tp[0]
&movq ($acc0,$mul1);
&movq ($car0,$mul1);
&pand ($acc0,$mask);
&pmuludq($mul1,$_n0); # *=n0
&pmuludq($car1,$mul1);
&paddq ($car1,$acc0);
&psrlq ($car0,32);
&psrlq ($car1,32);
&inc ($j); # j++
&set_label("inner");
&movd ($acc0,&DWP(0,$ap,$j,4)); # ap[j]
&movd ($acc1,&DWP(0,$np,$j,4)); # np[j]
&movd ($temp,&DWP($frame,"esp",$j,4));# tp[j]
&pmuludq($acc0,$mul0); # ap[j]*bp[i]
&pmuludq($acc1,$mul1); # np[j]*m1
&paddq ($car0,$temp); # +=tp[j]
&paddq ($car0,$acc0); # +=c0
&movq ($acc0,$car0);
&pand ($acc0,$mask);
&paddq ($car1,$acc1); # +=c1
&paddq ($car1,$acc0); # +=ap[j]*bp[i]+tp[j]
&movd (&DWP($frame-4,"esp",$j,4),$car1); # tp[j-1]=
&psrlq ($car0,32);
&psrlq ($car1,32);
&lea ($j,&DWP(1,$j)); # j++
&cmp ($j,$num);
&jl (&label("inner"));
&movd ($temp,&DWP($frame,"esp",$num,4));
&paddq ($car1,$car0);
&paddq ($car1,$temp);
&movq (&DWP($frame-4,"esp",$num,4),$car1);
&lea ($i,&DWP(1,$i)); # i++
&cmp ($i,$num);
&jl (&label("outer"));
&emms (); # done with mmx bank
&jmp (&label("common_tail"));
&set_label("non_sse2",16);
}
if (1) {
&mov ("esp",$_sp);
&xor ("eax","eax"); # signal "not fast enough [yet]"
&jmp (&label("just_leave"));
# The code below gives ~15% improvement on 512-bit benchmark
# *only*:-( On all other key lengths it's slower for up to 20%.
# This is because the original code path holds down the overall
# amount of multiplications by ~25% by deploying bn_sqr_words.
# In other words, for the code below to be competitive,
# dedicated squaring procedure is a must...
} else {
$inp="esi"; # integer path uses these registers differently
$word="edi";
$carry="ebp";
&sub ($num,1); # non-SSE2 path uses num-1
&mov ($inp,$_ap);
&mov ($word,$_bp);
&lea ("eax",&DWP(4,$word,$num,4)); # &bp[num]
&mov ($word,&DWP(0,$word)); # bp[0]
&mov ($_bpend,"eax");
&xor ($j,$j);
&xor ("edx","edx");
&set_label("mull",16);
&mov ("eax",&DWP(0,$inp,$j,4)); # ap[j]
&mov ($carry,"edx");
&mul ($word); # ap[j]*bp[0]
&lea ($j,&DWP(1,$j));
&add ("eax",$carry);
&adc ("edx",0);
&mov (&DWP($frame-4,"esp",$j,4),"eax"); # tp[j]=
&cmp ($j,$num);
&jb (&label("mull"));
&mov ("eax",&DWP(0,$inp,$num,4)); # ap[num-1]
&mov ($carry,"edx");
&mul ($word); # ap[num-1]*bp[0]
&add ("eax",$carry);
&adc ("edx",0);
&mov ($word,$_n0);
&mov ($inp,$_np);
&imul ($word,&DWP($frame,"esp")); # n0*tp[0]
&mov (&DWP($frame,"esp",$num,4),"eax"); # tp[num-1]=
&xor ($j,$j);
&mov (&DWP($frame+4,"esp",$num,4),"edx"); # tp[num]=
&mov (&DWP($frame+8,"esp",$num,4),$j); # tp[num+1]=
&mov ("eax",&DWP(0,$inp)); # np[0]
&mul ($word); # np[0]*m
&add ("eax",&DWP($frame,"esp")); # +=tp[0]
&adc ("edx",0);
&mov ($j,1);
&jmp (&label("2ndmadd"));
&set_label("1stmadd",16);
&mov ("eax",&DWP(0,$inp,$j,4)); # ap[j]
&mov ($carry,"edx");
&mul ($word); # ap[j]*bp[i]
&lea ($j,&DWP(1,$j));
&add ("eax",&DWP($frame-4,"esp",$j,4)); # +=tp[j]
&adc ("edx",0);
&add ("eax",$carry);
&adc ("edx",0);
&mov (&DWP($frame-4,"esp",$j,4),"eax"); # tp[j]=
&cmp ($j,$num);
&jb (&label("1stmadd"));
&mov ("eax",&DWP(0,$inp,$num,4)); # ap[num-1]
&mov ($carry,"edx");
&mul ($word); # ap[num-1]*bp[i]
&add ("eax",&DWP($frame,"esp",$num,4)); # +=tp[num-1]
&adc ("edx",0);
&add ("eax",$carry);
&adc ("edx",0);
&mov ($word,$_n0);
&mov ($inp,$_np);
&imul ($word,&DWP($frame,"esp")); # n0*tp[0]
&xor ($j,$j);
&add ("edx",&DWP($frame+4,"esp",$num,4)); # carry+=tp[num]
&mov (&DWP($frame,"esp",$num,4),"eax"); # tp[num-1]=
&adc ($j,0);
&mov (&DWP($frame+4,"esp",$num,4),"edx"); # tp[num]=
&mov (&DWP($frame+8,"esp",$num,4),$j); # tp[num+1]=
&mov ("eax",&DWP(0,$inp)); # np[0]
&mul ($word); # np[0]*m
&add ("eax",&DWP($frame,"esp")); # +=tp[0]
&adc ("edx",0);
&mov ($j,1);
&set_label("2ndmadd",16);
&mov ("eax",&DWP(0,$inp,$j,4)); # np[j]
&mov ($carry,"edx");
&mul ($word); # np[j]*m
&lea ($j,&DWP(1,$j));
&add ("eax",&DWP($frame-4,"esp",$j,4)); # +=tp[j]
&adc ("edx",0);
&add ("eax",$carry);
&adc ("edx",0);
&mov (&DWP($frame-8,"esp",$j,4),"eax"); # tp[j-1]=
&cmp ($j,$num);
&jb (&label("2ndmadd"));
&mov ("eax",&DWP(0,$inp,$num,4)); # np[num-1]
&mov ($carry,"edx");
&mul ($word); # np[num-1]*m
&add ("eax",&DWP($frame,"esp",$num,4)); # +=tp[num-1]
&adc ("edx",0);
&add ("eax",$carry);
&adc ("edx",0);
&mov (&DWP($frame-4,"esp",$num,4),"eax"); # tp[num-2]=
&xor ("eax","eax");
&add ("edx",&DWP($frame+4,"esp",$num,4)); # carry+=tp[num]
&adc ("eax",&DWP($frame+8,"esp",$num,4)); # +=tp[num+1]
&mov (&DWP($frame,"esp",$num,4),"edx"); # tp[num-1]=
&mov (&DWP($frame+4,"esp",$num,4),"eax"); # tp[num]=
&mov ($carry,$_bp); # &bp[i]
&add ($carry,4);
&cmp ($carry,$_bpend);
&je (&label("x86done"));
&mov ($word,&DWP(0,$carry)); # bp[i]
&mov ($inp,$_ap);
&mov ($_bp,$carry); # &bp[++i]
&xor ($j,$j);
&xor ("edx","edx");
&jmp (&label("1stmadd"));
&set_label("x86done",16);
&mov ($np,$_np); # make adjustments for tail processing
&add ($num,1);
}
&set_label("common_tail",16);
&mov ("esi",&DWP($frame,"esp",$num,4));# load upmost overflow bit
&mov ($rp,$_rp); # load result pointer
# [$ap and $bp are zapped]
&xor ($i,$i); # i=0
&lea ($j,&DWP(-1,$num)); # j=num-1
&cmp ("esi",0); # clears CF unconditionally
&jnz (&label("sub"));
&mov ("eax",&DWP($frame,"esp",$j,4));
&cmp ("eax",&DWP(0,$np,$j,4)); # tp[num-1]-np[num-1]?
&jae (&label("sub")); # if taken CF is cleared
&set_label("copy",16);
&mov ("eax",&DWP($frame,"esp",$j,4));
&mov (&DWP(0,$rp,$j,4),"eax"); # rp[i]=tp[i]
&mov (&DWP($frame,"esp",$j,4),$j); # zap temporary vector
&dec ($j);
&jge (&label("copy"));
&jmp (&label("exit"));
&set_label("sub",16);
&mov ("eax",&DWP($frame,"esp",$i,4));
&sbb ("eax",&DWP(0,$np,$i,4));
&mov (&DWP(0,$rp,$i,4),"eax"); # rp[i]=tp[i]-np[i]
&lea ($i,&DWP(1,$i)); # i++
&dec ($j); # doesn't affect CF!
&jge (&label("sub"));
&lea ($j,&DWP(-1,$num)); # j=num-1
&sbb ("esi",0); # esi holds upmost overflow bit
&jc (&label("copy"));
&set_label("zap",16);
&mov (&DWP($frame,"esp",$j,4),$i); # zap temporary vector
&dec ($j);
&jge (&label("zap"));
&set_label("exit",4);
&mov ("esp",$_sp); # pull saved stack pointer
&mov ("eax",1);
&set_label("just_leave");
&function_end("bn_mul_mont");
&asm_finish();
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