source/libs/gmp/gmp-src/mpn/x86/k6/cross.pl

   1 #! /usr/bin/perl
   2
   3 # Copyright 2000, 2001 Free Software Foundation, Inc.
   4 #
   5 #  This file is part of the GNU MP Library.
   6 #
   7 #  The GNU MP Library is free software; you can redistribute it and/or modify
   8 #  it under the terms of either:
   9 #
  10 #    * the GNU Lesser General Public License as published by the Free
  11 #      Software Foundation; either version 3 of the License, or (at your
  12 #      option) any later version.
  13 #
  14 #  or
  15 #
  16 #    * the GNU General Public License as published by the Free Software
  17 #      Foundation; either version 2 of the License, or (at your option) any
  18 #      later version.
  19 #
  20 #  or both in parallel, as here.
  21 #
  22 #  The GNU MP Library is distributed in the hope that it will be useful, but
  23 #  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24 #  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  25 #  for more details.
  26 #
  27 #  You should have received copies of the GNU General Public License and the
  28 #  GNU Lesser General Public License along with the GNU MP Library.  If not,
  29 #  see https://www.gnu.org/licenses/.
  30
  31
  32 # Usage: cross.pl [filename.o]...
  33 #
  34 # Produce an annotated disassembly of the given object files, indicating
  35 # certain code alignment and addressing mode problems afflicting K6 chips.
  36 # "ZZ" is used on all annotations, so this can be searched for.
  37 #
  38 # With no arguments, all .o files corresponding to .asm files are processed.
  39 # This is good in the mpn object directory of a k6*-*-* build.
  40 #
  41 # Code alignments of 8 bytes or more are handled.  When 32 is used, cache
  42 # line boundaries will fall in at offsets 0x20,0x40,etc and problems are
  43 # flagged at those locations.  When 16 is used, the line boundaries can also
  44 # fall at offsets 0x10,0x30,0x50,etc, depending where the file is loaded, so
  45 # problems are identified there too.  Likewise when 8 byte alignment is used
  46 # problems are flagged additionally at 0x08,0x18,0x28,etc.
  47 #
  48 # Usually 32 byte alignment is used for k6 routines, but less is certainly
  49 # possible if through good luck, or a little tweaking, cache line crossing
  50 # problems can be avoided at the extra locations.
  51 #
  52 # Bugs:
  53 #
  54 # Instructions without mod/rm bytes or which are already vector decoded are
  55 # unaffected by cache line boundary crossing, but not all of these have yet
  56 # been put in as exceptions.  All that occur in practice in GMP are present
  57 # though.
  58 #
  59 # There's no messages for using the vector decoded addressing mode (%esi),
  60 # but that's easy to avoid when coding.
  61 #
  62 # Future:
  63 #
  64 # Warn about jump targets that are poorly aligned (less than 2 instructions
  65 # before a cache line boundary).
  66
  67 use strict;
  68
  69 sub disassemble {
  70     my ($file) = @_;
  71     my ($addr,$b1,$b2,$b3, $prefix,$opcode,$modrm);
  72     my $align;
  73
  74     open (IN, "objdump -Srfh $file |")
  75         || die "Cannot open pipe from objdump\n";
  76     while (<IN>) {
  77         print;
  78
  79         if (/^[ \t]*[0-9]+[ \t]+\.text[ \t]/ && /2\*\*([0-9]+)$/) {
  80             $align = 1 << $1;
  81             if ($align < 8) {
  82                 print "ZZ cross.pl cannot handle alignment < 2**3\n";
  83                 $align = 8
  84             }
  85         }
  86
  87         if (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)[ \t]+([0-9a-f]+)[ \t]+([0-9a-f]+)/) {
  88             ($addr,$b1,$b2,$b3) = ($1,$2,$3,$4);
  89
  90         } elsif (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)[ \t]+([0-9a-f]+)/) {
  91             ($addr,$b1,$b2,$b3) = ($1,$2,$3,'');
  92
  93         } elsif (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)/) {
  94             ($addr,$b1,$b2,$b3) = ($1,$2,'','');
  95
  96         } else {
  97             next;
  98         }
  99
 100         if ($b1 =~ /0f/) {
 101             $prefix = $b1;
 102             $opcode = $b2;
 103             $modrm = $b3;
 104         } else {
 105             $prefix = '';
 106             $opcode = $b1;
 107             $modrm = $b2;
 108         }
 109
 110         # modrm of the form 00-xxx-100 with an 0F prefix is the problem case
 111         # for K6 and pre-CXT K6-2
 112         if ($prefix =~ /0f/
 113             && $opcode !~ /^8/         # jcond disp32
 114             && $modrm =~ /^[0-3][4c]/) {
 115             print "ZZ ($file) >3 bytes to determine instruction length [K6]\n";
 116         }
 117
 118         # with just an opcode, starting 1f mod 20h
 119         if (($align==32 && $addr =~ /[13579bdf]f$/
 120              || $align==16 && $addr =~ /f$/
 121              || $align==8 && $addr =~ /[7f]$/)
 122             && $prefix !~ /0f/
 123             && $opcode !~ /1[012345]/ # adc
 124             && $opcode !~ /1[89abcd]/ # sbb
 125             && $opcode !~ /^4/        # inc/dec reg
 126             && $opcode !~ /^5/        # push/pop reg
 127             && $opcode !~ /68/        # push $imm32
 128             && $opcode !~ /^7/        # jcond disp8
 129             && $opcode !~ /a[89]/     # test+imm
 130             && $opcode !~ /a[a-f]/    # stos/lods/scas
 131             && $opcode !~ /b8/        # movl $imm32,%eax
 132             && $opcode !~ /d[0123]/   # rcl
 133             && $opcode !~ /e[0123]/   # loop/loopz/loopnz/jcxz
 134             && $opcode !~ /e8/        # call disp32
 135             && $opcode !~ /e[9b]/     # jmp disp32/disp8
 136             && $opcode !~ /f[89abcd]/ # clc,stc,cli,sti,cld,std
 137             && !($opcode =~ /f[67]/          # grp 1
 138                  && $modrm =~ /^[2367abef]/) # mul, imul, div, idiv
 139             && $modrm !~ /^$/) {
 140             print "ZZ ($file) opcode/modrm cross 32-byte boundary\n";
 141         }
 142
 143         # with an 0F prefix, anything starting at 1f mod 20h
 144         if (($align==32 && $addr =~ /[13579bdf][f]$/
 145              || $align==16 && $addr =~ /f$/
 146              || $align==8 && $addr =~ /[7f]$/)
 147             && $prefix =~ /0f/
 148             && $opcode !~ /af/        # imul
 149             && $opcode !~ /a[45]/     # shldl
 150             && $opcode !~ /a[cd]/     # shrdl
 151             ) {
 152             print "ZZ ($file) prefix/opcode cross 32-byte boundary\n";
 153         }
 154
 155         # with an 0F prefix, anything with mod/rm starting at 1e mod 20h
 156         if (($align==32 && $addr =~ /[13579bdf][e]$/
 157              || $align==16 && $addr =~ /[e]$/
 158              || $align==8 && $addr =~ /[6e]$/)
 159             && $prefix =~ /0f/
 160              && $opcode !~ /^8/        # jcond disp32
 161              && $opcode !~ /af/        # imull reg,reg
 162              && $opcode !~ /a[45]/     # shldl
 163              && $opcode !~ /a[cd]/     # shrdl
 164             && $modrm !~ /^$/) {
 165             print "ZZ ($file) prefix/opcode/modrm cross 32-byte boundary\n";
 166         }
 167     }
 168     close IN || die "Error from objdump (or objdump not available)\n";
 169 }
 170
 171
 172 my @files;
 173 if ($#ARGV >= 0) {
 174     @files = @ARGV;
 175 } else {
 176     @files = glob "*.asm";
 177     map {s/.asm/.o/} @files;
 178 }
 179
 180 foreach (@files)  {
 181     disassemble($_);
 182 }