+45% RC4 performance boost on Intel EM64T core. Unrolled loop providing
[openssl.git] / crypto / rc4 / asm / rc4-586.pl
1 #!/usr/local/bin/perl
2
3 # At some point it became apparent that the original SSLeay RC4
4 # assembler implementation performs suboptimaly on latest IA-32
5 # microarchitectures. After re-tuning performance has changed as
6 # following:
7 #
8 # Pentium       +0%
9 # Pentium III   +17%
10 # AMD           +52%(*)
11 # P4            +180%(**)
12 #
13 # (*)   This number is actually a trade-off:-) It's possible to
14 #       achieve +72%, but at the cost of -48% off PIII performance.
15 #       In other words code performing further 13% faster on AMD
16 #       would perform almost 2 times slower on Intel PIII...
17 #       For reference! This code delivers ~80% of rc4-amd64.pl
18 #       performance on the same Opteron machine.
19 # (**)  This number requires compressed key schedule set up by
20 #       RC4_set_key and therefore doesn't apply to 0.9.7 [option for
21 #       compressed key schedule is implemented in 0.9.8 and later,
22 #       see commentary section in rc4_skey.c for further details].
23 #
24 #                                       <appro@fy.chalmers.se>
25
26 push(@INC,"perlasm","../../perlasm");
27 require "x86asm.pl";
28
29 &asm_init($ARGV[0],"rc4-586.pl");
30
31 $x="eax";
32 $y="ebx";
33 $tx="ecx";
34 $ty="edx";
35 $in="esi";
36 $out="edi";
37 $d="ebp";
38
39 &RC4("RC4");
40
41 &asm_finish();
42
43 sub RC4_loop
44         {
45         local($n,$p,$char)=@_;
46
47         &comment("Round $n");
48
49         if ($char)
50                 {
51                 if ($p >= 0)
52                         {
53                          &mov($ty,      &swtmp(2));
54                         &cmp($ty,       $in);
55                          &jbe(&label("finished"));
56                         &inc($in);
57                         }
58                 else
59                         {
60                         &add($ty,       8);
61                          &inc($in);
62                         &cmp($ty,       $in);
63                          &jb(&label("finished"));
64                         &mov(&swtmp(2), $ty);
65                         }
66                 }
67         # Moved out
68         # &mov( $tx,            &DWP(0,$d,$x,4)) if $p < 0;
69
70         &add(   &LB($y),        &LB($tx));
71         &mov(   $ty,            &DWP(0,$d,$y,4));
72          # XXX
73         &mov(   &DWP(0,$d,$x,4),$ty);
74          &add(  $ty,            $tx);
75         &mov(   &DWP(0,$d,$y,4),$tx);
76          &and(  $ty,            0xff);
77          &inc(  &LB($x));                       # NEXT ROUND
78         &mov(   $tx,            &DWP(0,$d,$x,4)) if $p < 1; # NEXT ROUND
79          &mov(  $ty,            &DWP(0,$d,$ty,4));
80
81         if (!$char)
82                 {
83                 #moved up into last round
84                 if ($p >= 1)
85                         {
86                         &add(   $out,   8)
87                         }
88                 &movb(  &BP($n,"esp","",0),     &LB($ty));
89                 }
90         else
91                 {
92                 # Note in+=8 has occured
93                 &movb(  &HB($ty),       &BP(-1,$in,"",0));
94                  # XXX
95                 &xorb(&LB($ty),         &HB($ty));
96                  # XXX
97                 &movb(&BP($n,$out,"",0),&LB($ty));
98                 }
99         }
100
101
102 sub RC4
103         {
104         local($name)=@_;
105
106         &function_begin_B($name,"");
107
108         &mov($ty,&wparam(1));           # len
109         &cmp($ty,0);
110         &jne(&label("proceed"));
111         &ret();
112         &set_label("proceed");
113
114         &comment("");
115
116         &push("ebp");
117          &push("ebx");
118         &push("esi");
119          &xor(  $x,     $x);            # avoid partial register stalls
120         &push("edi");
121          &xor(  $y,     $y);            # avoid partial register stalls
122         &mov(   $d,     &wparam(0));    # key
123          &mov(  $in,    &wparam(2));
124
125         &movb(  &LB($x),        &BP(0,$d,"",1));
126          &movb( &LB($y),        &BP(4,$d,"",1));
127
128         &mov(   $out,   &wparam(3));
129          &inc(  &LB($x));
130
131         &stack_push(3); # 3 temp variables
132          &add(  $d,     8);
133
134         # detect compressed schedule, see commentary section in rc4_skey.c...
135         # in 0.9.7 context ~50 bytes below RC4_CHAR label remain redundant,
136         # as compressed key schedule is set up in 0.9.8 and later.
137         &cmp(&DWP(256,$d),-1);
138         &je(&label("RC4_CHAR"));
139
140          &lea(  $ty,    &DWP(-8,$ty,$in));
141
142         # check for 0 length input
143
144          &mov(  &swtmp(2),      $ty);   # this is now address to exit at
145         &mov(   $tx,    &DWP(0,$d,$x,4));
146
147          &cmp(  $ty,    $in);
148         &jb(    &label("end")); # less than 8 bytes
149
150         &set_label("start");
151
152         # filling DELAY SLOT
153         &add(   $in,    8);
154
155         &RC4_loop(0,-1,0);
156         &RC4_loop(1,0,0);
157         &RC4_loop(2,0,0);
158         &RC4_loop(3,0,0);
159         &RC4_loop(4,0,0);
160         &RC4_loop(5,0,0);
161         &RC4_loop(6,0,0);
162         &RC4_loop(7,1,0);
163         
164         &comment("apply the cipher text");
165         # xor the cipher data with input
166
167         #&add(  $out,   8); #moved up into last round
168
169         &mov(   $tx,    &swtmp(0));
170          &mov(  $ty,    &DWP(-8,$in,"",0));
171         &xor(   $tx,    $ty);
172          &mov(  $ty,    &DWP(-4,$in,"",0)); 
173         &mov(   &DWP(-8,$out,"",0),     $tx);
174          &mov(  $tx,    &swtmp(1));
175         &xor(   $tx,    $ty);
176          &mov(  $ty,    &swtmp(2));     # load end ptr;
177         &mov(   &DWP(-4,$out,"",0),     $tx);
178          &mov(  $tx,            &DWP(0,$d,$x,4));
179         &cmp($in,       $ty);
180          &jbe(&label("start"));
181
182         &set_label("end");
183
184         # There is quite a bit of extra crap in RC4_loop() for this
185         # first round
186         &RC4_loop(0,-1,1);
187         &RC4_loop(1,0,1);
188         &RC4_loop(2,0,1);
189         &RC4_loop(3,0,1);
190         &RC4_loop(4,0,1);
191         &RC4_loop(5,0,1);
192         &RC4_loop(6,1,1);
193
194         &jmp(&label("finished"));
195
196         &align(16);
197         # this is essentially Intel P4 specific codepath, see rc4_skey.c,
198         # and is engaged in 0.9.8 and later context...
199         &set_label("RC4_CHAR");
200
201         &lea    ($ty,&DWP(0,$in,$ty));
202         &mov    (&swtmp(2),$ty);
203
204         # strangely enough unrolled loop performs over 20% slower...
205         &set_label("RC4_CHAR_loop");
206                 &movz   ($tx,&BP(0,$d,$x));
207                 &add    (&LB($y),&LB($tx));
208                 &movz   ($ty,&BP(0,$d,$y));
209                 &movb   (&BP(0,$d,$y),&LB($tx));
210                 &movb   (&BP(0,$d,$x),&LB($ty));
211                 &add    (&LB($ty),&LB($tx));
212                 &movz   ($ty,&BP(0,$d,$ty));
213                 &xorb   (&LB($ty),&BP(0,$in));
214                 &movb   (&BP(0,$out),&LB($ty));
215                 &inc    (&LB($x));
216                 &inc    ($in);
217                 &inc    ($out);
218                 &cmp    ($in,&swtmp(2));
219         &jb     (&label("RC4_CHAR_loop"));
220
221         &set_label("finished");
222         &dec(   $x);
223          &stack_pop(3);
224         &movb(  &BP(-4,$d,"",0),&LB($y));
225          &movb( &BP(-8,$d,"",0),&LB($x));
226
227         &function_end($name);
228         }
229