#!/usr/bin/env perl
# ====================================================================
# [Re]written by Andy Polyakov <appro@openssl.org> 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/.
# ====================================================================
# "[Re]written" was achieved in two major overhauls. In 2004 BODY_*
# functions were re-implemented to address P4 performance issue [see
# commentary below], and in 2006 the rest was rewritten in order to
# gain freedom to liberate licensing terms.
# January, September 2004.
#
# It was noted that Intel IA-32 C compiler generates code which
# performs ~30% *faster* on P4 CPU than original *hand-coded*
# SHA1 assembler implementation. To address this problem (and
# prove that humans are still better than machines:-), the
# original code was overhauled, which resulted in following
# performance changes:
#
# compared with original compared with Intel cc
# assembler impl. generated code
# Pentium -16% +48%
# PIII/AMD +8% +16%
# P4 +85%(!) +45%
#
# As you can see Pentium came out as looser:-( Yet I reckoned that
# improvement on P4 outweights the loss and incorporate this
# re-tuned code to 0.9.7 and later.
# ----------------------------------------------------------------
# <appro@fy.chalmers.se>
# August 2009.
#
# George Spelvin has tipped that F_40_59(b,c,d) can be rewritten as
# '(c&d) + (b&(c^d))', which allows to accumulate partial results
# and lighten "pressure" on scratch registers. This resulted in
# >12% performance improvement on contemporary AMD cores (with no
# degradation on other CPUs:-). Also, the code was revised to maximize
# "distance" between instructions producing input to 'lea' instruction
# and the 'lea' instruction itself, which is essential for Intel Atom
# core and resulted in ~15% improvement.
# October 2010.
#
# Add SSSE3, Supplemental[!] SSE3, implementation. The idea behind it
# is to offload message schedule denoted by Wt in NIST specification,
# or Xupdate in OpenSSL source, to SIMD unit. The idea is not novel,
# and in SSE2 context was first explored by Dean Gaudet in 2004, see
# http://arctic.org/~dean/crypto/sha1.html. Since then several things
# have changed that made it interesting again:
#
# a) XMM units became faster and wider;
# b) instruction set became more versatile;
# c) an important observation was made by Max Locktykhin, which made
# it possible to reduce amount of instructions required to perform
# the operation in question, for further details see
# http://software.intel.com/en-us/articles/improving-the-performance-of-the-secure-hash-algorithm-1/.
# April 2011.
#
# Add AVX code path, probably most controversial... The thing is that
# switch to AVX alone improves performance by as little as 4% in
# comparison to SSSE3 code path. But below result doesn't look like
# 4% improvement... Trouble is that Sandy Bridge decodes 'ro[rl]' as
# pair of �-ops, and it's the additional �-ops, two per round, that
# make it run slower than Core2 and Westmere. But 'sh[rl]d' is decoded
# as single �-op by Sandy Bridge and it's replacing 'ro[rl]' with
# equivalent 'sh[rl]d' that is responsible for the impressive 5.1
# cycles per processed byte. But 'sh[rl]d' is not something that used
# to be fast, nor does it appear to be fast in upcoming Bulldozer
# [according to its optimization manual]. Which is why AVX code path
# is guarded by *both* AVX and synthetic bit denoting Intel CPUs.
# One can argue that it's unfair to AMD, but without 'sh[rl]d' it
# makes no sense to keep the AVX code path. If somebody feels that
# strongly, it's probably more appropriate to discuss possibility of
# using vector rotate XOP on AMD...
######################################################################
# Current performance is summarized in following table. Numbers are
# CPU clock cycles spent to process single byte (less is better).
#
# x86 SSSE3 AVX
# Pentium 15.7 -
# PIII 11.5 -
# P4 10.6 -
# AMD K8 7.1 -
# Core2 7.3 6.0/+22% -
# Atom 12.5 9.3(*)/+35% -
# Westmere 7.3 5.5/+33% -
# Sandy Bridge 8.8 6.2/+40% 5.1(**)/+73%
# Ivy Bridge 7.2 4.8/+51% 4.7(**)/+53%
# Haswell 6.5 4.3/+51% 4.1(**)/+58%
# Bulldozer 11.6 6.0/+92%
# VIA Nano 10.6 7.5/+41%
#
# (*) Loop is 1056 instructions long and expected result is ~8.25.
# It remains mystery [to me] why ILP is limited to 1.7.
#
# (**) As per above comment, the result is for AVX *plus* sh[rl]d.
$0 =~ m/(.*[\/\\])[^\/\\]+$/; $dir=$1;
push(@INC,"${dir}","${dir}../../perlasm");
require "x86asm.pl";
&asm_init($ARGV[0],"sha1-586.pl",$ARGV[$#ARGV] eq