1 files changed, 85 insertions, 29 deletions

diff --git a/src/lib/libcrypto/rc4/asm/rc4-586.pl b/src/lib/libcrypto/rc4/asm/rc4-586.pl
index 7ef889e5a1..d6e98f0811 100644
--- a/src/lib/libcrypto/rc4/asm/rc4-586.pl
+++ b/src/lib/libcrypto/rc4/asm/rc4-586.pl
@@ -1,16 +1,37 @@
 #!/usr/local/bin/perl
 
-# define for pentium pro friendly version
+# At some point it became apparent that the original SSLeay RC4
+# assembler implementation performs suboptimaly on latest IA-32
+# microarchitectures. After re-tuning performance has changed as
+# following:
+#
+# Pentium       +0%
+# Pentium III   +17%
+# AMD           +52%(*)
+# P4            +180%(**)
+#
+# (*)   This number is actually a trade-off:-) It's possible to
+#       achieve +72%, but at the cost of -48% off PIII performance.
+#       In other words code performing further 13% faster on AMD
+#       would perform almost 2 times slower on Intel PIII...
+#       For reference! This code delivers ~80% of rc4-amd64.pl
+#       performance on the same Opteron machine.
+# (**)  This number requires compressed key schedule set up by
+#       RC4_set_key and therefore doesn't apply to 0.9.7 [option for
+#       compressed key schedule is implemented in 0.9.8 and later,
+#       see commentary section in rc4_skey.c for further details].
+#
+#                                       <appro@fy.chalmers.se>
 
 push(@INC,"perlasm","../../perlasm");
 require "x86asm.pl";
 
 &asm_init($ARGV[0],"rc4-586.pl");
 
-$tx="eax";
-$ty="ebx";
-$x="ecx";
-$y="edx";
+$x="eax";
+$y="ebx";
+$tx="ecx";
+$ty="edx";
 $in="esi";
 $out="edi";
 $d="ebp";
@@ -31,7 +52,7 @@ sub RC4_loop
                         {
                          &mov($ty,      &swtmp(2));
                         &cmp($ty,       $in);
-                         &jle(&label("finished"));
+                         &jbe(&label("finished"));
                         &inc($in);
                         }
                 else
@@ -39,27 +60,23 @@ sub RC4_loop
                         &add($ty,       8);
                          &inc($in);
                         &cmp($ty,       $in);
-                         &jl(&label("finished"));
+                         &jb(&label("finished"));
                         &mov(&swtmp(2), $ty);
                         }
                 }
         # Moved out
         # &mov( $tx,            &DWP(0,$d,$x,4)) if $p < 0;
 
-         &add(  $y,             $tx);
-        &and(   $y,             0xff);
-         &inc(  $x);                    # NEXT ROUND 
+        &add(   &LB($y),        &LB($tx));
         &mov(   $ty,            &DWP(0,$d,$y,4));
          # XXX
-        &mov(   &DWP(-4,$d,$x,4),$ty);                  # AGI
+        &mov(   &DWP(0,$d,$x,4),$ty);
          &add(  $ty,            $tx);
-        &and(   $x,             0xff);  # NEXT ROUND
-         &and(  $ty,            0xff);
         &mov(   &DWP(0,$d,$y,4),$tx);
-         &nop();
-        &mov(   $ty,            &DWP(0,$d,$ty,4));
-         &mov(  $tx,            &DWP(0,$d,$x,4)) if $p < 1; # NEXT ROUND
-         # XXX
+         &and(  $ty,            0xff);
+         &inc(  &LB($x));                       # NEXT ROUND
+        &mov(   $tx,            &DWP(0,$d,$x,4)) if $p < 1; # NEXT ROUND
+         &mov(  $ty,            &DWP(0,$d,$ty,4));
 
         if (!$char)
                 {
@@ -88,35 +105,47 @@ sub RC4
 
         &function_begin_B($name,"");
 
+        &mov($ty,&wparam(1));           # len
+        &cmp($ty,0);
+        &jne(&label("proceed"));
+        &ret();
+        &set_label("proceed");
+
         &comment("");
 
         &push("ebp");
          &push("ebx");
-        &mov(   $d,     &wparam(0));    # key
-         &mov(  $ty,    &wparam(1));    # num
         &push("esi");
-         &push("edi");
+         &xor(  $x,     $x);            # avoid partial register stalls
+        &push("edi");
+         &xor(  $y,     $y);            # avoid partial register stalls
+        &mov(   $d,     &wparam(0));    # key
+         &mov(  $in,    &wparam(2));
 
-        &mov(   $x,     &DWP(0,$d,"",1));
-         &mov(  $y,     &DWP(4,$d,"",1));
+        &movb(  &LB($x),        &BP(0,$d,"",1));
+         &movb( &LB($y),        &BP(4,$d,"",1));
 
-        &mov(   $in,    &wparam(2));
-         &inc(  $x);
+        &mov(   $out,   &wparam(3));
+         &inc(  &LB($x));
 
         &stack_push(3); # 3 temp variables
          &add(  $d,     8);
-        &and(   $x,             0xff);
+
+        # detect compressed schedule, see commentary section in rc4_skey.c...
+        # in 0.9.7 context ~50 bytes below RC4_CHAR label remain redundant,
+        # as compressed key schedule is set up in 0.9.8 and later.
+        &cmp(&DWP(256,$d),-1);
+        &je(&label("RC4_CHAR"));
 
          &lea(  $ty,    &DWP(-8,$ty,$in));
 
         # check for 0 length input
 
-        &mov(   $out,   &wparam(3));
          &mov(  &swtmp(2),      $ty);   # this is now address to exit at
         &mov(   $tx,    &DWP(0,$d,$x,4));
 
          &cmp(  $ty,    $in);
-        &jl(    &label("end")); # less than 8 bytes
+        &jb(    &label("end")); # less than 8 bytes
 
         &set_label("start");
 
@@ -148,7 +177,7 @@ sub RC4
         &mov(   &DWP(-4,$out,"",0),     $tx);
          &mov(  $tx,            &DWP(0,$d,$x,4));
         &cmp($in,       $ty);
-         &jle(&label("start"));
+         &jbe(&label("start"));
 
         &set_label("end");
 
@@ -162,10 +191,37 @@ sub RC4
         &RC4_loop(5,0,1);
         &RC4_loop(6,1,1);
 
+        &jmp(&label("finished"));
+
+        &align(16);
+        # this is essentially Intel P4 specific codepath, see rc4_skey.c,
+        # and is engaged in 0.9.8 and later context...
+        &set_label("RC4_CHAR");
+
+        &lea    ($ty,&DWP(0,$in,$ty));
+        &mov    (&swtmp(2),$ty);
+
+        # strangely enough unrolled loop performs over 20% slower...
+        &set_label("RC4_CHAR_loop");
+                &movz   ($tx,&BP(0,$d,$x));
+                &add    (&LB($y),&LB($tx));
+                &movz   ($ty,&BP(0,$d,$y));
+                &movb   (&BP(0,$d,$y),&LB($tx));
+                &movb   (&BP(0,$d,$x),&LB($ty));
+                &add    (&LB($ty),&LB($tx));
+                &movz   ($ty,&BP(0,$d,$ty));
+                &xorb   (&LB($ty),&BP(0,$in));
+                &movb   (&BP(0,$out),&LB($ty));
+                &inc    (&LB($x));
+                &inc    ($in);
+                &inc    ($out);
+                &cmp    ($in,&swtmp(2));
+        &jb     (&label("RC4_CHAR_loop"));
+
         &set_label("finished");
         &dec(   $x);
          &stack_pop(3);
-        &mov(   &DWP(-4,$d,"",0),$y);
+        &movb(  &BP(-4,$d,"",0),&LB($y));
          &movb( &BP(-8,$d,"",0),&LB($x));
 
         &function_end($name);