1 | \input texinfo @c -*- texinfo -*-
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2 | @c %**start of header
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3 | @setfilename tcc-doc.info
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4 | @settitle Tiny C Compiler Reference Documentation
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5 | @dircategory Software development
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6 | @direntry
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7 | * TCC: (tcc-doc). The Tiny C Compiler.
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8 | @end direntry
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9 | @c %**end of header
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10 |
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11 | @include config.texi
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12 |
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13 | @iftex
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14 | @titlepage
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15 | @afourpaper
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16 | @sp 7
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17 | @center @titlefont{Tiny C Compiler Reference Documentation}
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18 | @sp 3
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19 | @end titlepage
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20 | @headings double
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21 | @end iftex
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22 |
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23 | @contents
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24 |
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25 | @node Top, Introduction, (dir), (dir)
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26 | @top Tiny C Compiler Reference Documentation
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27 |
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28 | This manual documents version @value{VERSION} of the Tiny C Compiler.
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29 |
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30 | @menu
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31 | * Introduction:: Introduction to tcc.
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32 | * Invoke:: Invocation of tcc (command line, options).
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33 | * Clang:: ANSI C and extensions.
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34 | * asm:: Assembler syntax.
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35 | * linker:: Output file generation and supported targets.
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36 | * Bounds:: Automatic bounds-checking of C code.
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37 | * Libtcc:: The libtcc library.
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38 | * devel:: Guide for Developers.
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39 | @end menu
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40 |
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41 |
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42 | @node Introduction
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43 | @chapter Introduction
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44 |
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45 | TinyCC (aka TCC) is a small but hyper fast C compiler. Unlike other C
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46 | compilers, it is meant to be self-relying: you do not need an
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47 | external assembler or linker because TCC does that for you.
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48 |
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49 | TCC compiles so @emph{fast} that even for big projects @code{Makefile}s may
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50 | not be necessary.
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51 |
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52 | TCC not only supports ANSI C, but also most of the new ISO C99
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53 | standard and many GNUC extensions including inline assembly.
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54 |
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55 | TCC can also be used to make @emph{C scripts}, i.e. pieces of C source
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56 | that you run as a Perl or Python script. Compilation is so fast that
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57 | your script will be as fast as if it was an executable.
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58 |
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59 | TCC can also automatically generate memory and bound checks
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60 | (@pxref{Bounds}) while allowing all C pointers operations. TCC can do
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61 | these checks even if non patched libraries are used.
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62 |
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63 | With @code{libtcc}, you can use TCC as a backend for dynamic code
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64 | generation (@pxref{Libtcc}).
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65 |
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66 | TCC mainly supports the i386 target on Linux and Windows. There are alpha
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67 | ports for the ARM (@code{arm-tcc}) and the TMS320C67xx targets
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68 | (@code{c67-tcc}). More information about the ARM port is available at
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69 | @url{http://lists.gnu.org/archive/html/tinycc-devel/2003-10/msg00044.html}.
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70 |
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71 | For usage on Windows, see also @url{tcc-win32.txt}.
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72 |
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73 | @node Invoke
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74 | @chapter Command line invocation
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75 |
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76 | @section Quick start
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77 |
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78 | @example
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79 | @c man begin SYNOPSIS
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80 | usage: tcc [options] [@var{infile1} @var{infile2}@dots{}] [@option{-run} @var{infile} @var{args}@dots{}]
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81 | @c man end
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82 | @end example
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83 |
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84 | @noindent
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85 | @c man begin DESCRIPTION
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86 | TCC options are a very much like gcc options. The main difference is that TCC
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87 | can also execute directly the resulting program and give it runtime
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88 | arguments.
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89 |
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90 | Here are some examples to understand the logic:
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91 |
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92 | @table @code
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93 | @item @samp{tcc -run a.c}
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94 | Compile @file{a.c} and execute it directly
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95 |
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96 | @item @samp{tcc -run a.c arg1}
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97 | Compile a.c and execute it directly. arg1 is given as first argument to
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98 | the @code{main()} of a.c.
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99 |
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100 | @item @samp{tcc a.c -run b.c arg1}
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101 | Compile @file{a.c} and @file{b.c}, link them together and execute them. arg1 is given
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102 | as first argument to the @code{main()} of the resulting program.
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103 | @ignore
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104 | Because multiple C files are specified, @option{--} are necessary to clearly
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105 | separate the program arguments from the TCC options.
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106 | @end ignore
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107 |
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108 | @item @samp{tcc -o myprog a.c b.c}
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109 | Compile @file{a.c} and @file{b.c}, link them and generate the executable @file{myprog}.
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110 |
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111 | @item @samp{tcc -o myprog a.o b.o}
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112 | link @file{a.o} and @file{b.o} together and generate the executable @file{myprog}.
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113 |
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114 | @item @samp{tcc -c a.c}
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115 | Compile @file{a.c} and generate object file @file{a.o}.
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116 |
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117 | @item @samp{tcc -c asmfile.S}
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118 | Preprocess with C preprocess and assemble @file{asmfile.S} and generate
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119 | object file @file{asmfile.o}.
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120 |
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121 | @item @samp{tcc -c asmfile.s}
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122 | Assemble (but not preprocess) @file{asmfile.s} and generate object file
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123 | @file{asmfile.o}.
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124 |
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125 | @item @samp{tcc -r -o ab.o a.c b.c}
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126 | Compile @file{a.c} and @file{b.c}, link them together and generate the object file @file{ab.o}.
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127 |
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128 | @end table
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129 |
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130 | Scripting:
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131 |
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132 | TCC can be invoked from @emph{scripts}, just as shell scripts. You just
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133 | need to add @code{#!/usr/local/bin/tcc -run} at the start of your C source:
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134 |
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135 | @example
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136 | #!/usr/local/bin/tcc -run
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137 | #include <stdio.h>
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138 |
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139 | int main()
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140 | @{
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141 | printf("Hello World\n");
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142 | return 0;
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143 | @}
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144 | @end example
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145 |
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146 | TCC can read C source code from @emph{standard input} when @option{-} is used in
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147 | place of @option{infile}. Example:
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148 |
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149 | @example
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150 | echo 'main()@{puts("hello");@}' | tcc -run -
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151 | @end example
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152 | @c man end
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153 |
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154 | @section Option summary
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155 |
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156 | General Options:
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157 |
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158 | @c man begin OPTIONS
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159 | @table @option
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160 | @item -c
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161 | Generate an object file.
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162 |
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163 | @item -o outfile
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164 | Put object file, executable, or dll into output file @file{outfile}.
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165 |
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166 | @item -run source [args...]
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167 | Compile file @var{source} and run it with the command line arguments
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168 | @var{args}. In order to be able to give more than one argument to a
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169 | script, several TCC options can be given @emph{after} the
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170 | @option{-run} option, separated by spaces:
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171 | @example
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172 | tcc "-run -L/usr/X11R6/lib -lX11" ex4.c
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173 | @end example
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174 | In a script, it gives the following header:
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175 | @example
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176 | #!/usr/local/bin/tcc -run -L/usr/X11R6/lib -lX11
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177 | @end example
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178 |
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179 | @item -v
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180 | Display TCC version.
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181 |
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182 | @item -vv
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183 | Show included files. As sole argument, print search dirs. -vvv shows tries too.
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184 |
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185 | @item -bench
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186 | Display compilation statistics.
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187 |
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188 | @end table
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189 |
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190 | Preprocessor options:
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191 |
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192 | @table @option
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193 | @item -Idir
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194 | Specify an additional include path. Include paths are searched in the
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195 | order they are specified.
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196 |
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197 | System include paths are always searched after. The default system
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198 | include paths are: @file{/usr/local/include}, @file{/usr/include}
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199 | and @file{PREFIX/lib/tcc/include}. (@file{PREFIX} is usually
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200 | @file{/usr} or @file{/usr/local}).
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201 |
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202 | @item -Dsym[=val]
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203 | Define preprocessor symbol @samp{sym} to
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204 | val. If val is not present, its value is @samp{1}. Function-like macros can
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205 | also be defined: @option{-DF(a)=a+1}
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206 |
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207 | @item -Usym
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208 | Undefine preprocessor symbol @samp{sym}.
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209 |
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210 | @item -E
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211 | Preprocess only, to stdout or file (with -o).
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212 |
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213 | @end table
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214 |
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215 | Compilation flags:
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216 |
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217 | Note: each of the following options has a negative form beginning with
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218 | @option{-fno-}.
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219 |
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220 | @table @option
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221 | @item -funsigned-char
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222 | Let the @code{char} type be unsigned.
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223 |
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224 | @item -fsigned-char
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225 | Let the @code{char} type be signed.
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226 |
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227 | @item -fno-common
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228 | Do not generate common symbols for uninitialized data.
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229 |
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230 | @item -fleading-underscore
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231 | Add a leading underscore at the beginning of each C symbol.
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232 |
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233 | @item -fms-extensions
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234 | Allow a MS C compiler extensions to the language. Currently this
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235 | assumes a nested named structure declaration without an identifier
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236 | behaves like an unnamed one.
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237 |
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238 | @item -fdollars-in-identifiers
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239 | Allow dollar signs in identifiers
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240 |
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241 | @end table
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242 |
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243 | Warning options:
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244 |
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245 | @table @option
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246 | @item -w
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247 | Disable all warnings.
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248 |
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249 | @end table
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250 |
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251 | Note: each of the following warning options has a negative form beginning with
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252 | @option{-Wno-}.
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253 |
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254 | @table @option
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255 | @item -Wimplicit-function-declaration
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256 | Warn about implicit function declaration.
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257 |
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258 | @item -Wunsupported
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259 | Warn about unsupported GCC features that are ignored by TCC.
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260 |
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261 | @item -Wwrite-strings
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262 | Make string constants be of type @code{const char *} instead of @code{char
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263 | *}.
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264 |
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265 | @item -Werror
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266 | Abort compilation if warnings are issued.
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267 |
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268 | @item -Wall
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269 | Activate all warnings, except @option{-Werror}, @option{-Wunusupported} and
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270 | @option{-Wwrite-strings}.
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271 |
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272 | @end table
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273 |
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274 | Linker options:
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275 |
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276 | @table @option
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277 | @item -Ldir
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278 | Specify an additional static library path for the @option{-l} option. The
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279 | default library paths are @file{/usr/local/lib}, @file{/usr/lib} and @file{/lib}.
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280 |
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281 | @item -lxxx
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282 | Link your program with dynamic library libxxx.so or static library
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283 | libxxx.a. The library is searched in the paths specified by the
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284 | @option{-L} option and @env{LIBRARY_PATH} variable.
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285 |
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286 | @item -Bdir
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287 | Set the path where the tcc internal libraries (and include files) can be
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288 | found (default is @file{PREFIX/lib/tcc}).
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289 |
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290 | @item -shared
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291 | Generate a shared library instead of an executable.
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292 |
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293 | @item -soname name
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294 | set name for shared library to be used at runtime
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295 |
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296 | @item -static
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297 | Generate a statically linked executable (default is a shared linked
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298 | executable).
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299 |
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300 | @item -rdynamic
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301 | Export global symbols to the dynamic linker. It is useful when a library
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302 | opened with @code{dlopen()} needs to access executable symbols.
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303 |
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304 | @item -r
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305 | Generate an object file combining all input files.
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306 |
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307 | @item -Wl,-rpath=path
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308 | Put custom search path for dynamic libraries into executable.
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309 |
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310 | @item -Wl,--enable-new-dtags
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311 | When putting a custom search path for dynamic libraries into the executable,
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312 | create the new ELF dynamic tag DT_RUNPATH instead of the old legacy DT_RPATH.
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313 |
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314 | @item -Wl,--oformat=fmt
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315 | Use @var{fmt} as output format. The supported output formats are:
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316 | @table @code
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317 | @item elf32-i386
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318 | ELF output format (default)
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319 | @item binary
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320 | Binary image (only for executable output)
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321 | @item coff
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322 | COFF output format (only for executable output for TMS320C67xx target)
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323 | @end table
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324 |
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325 | @item -Wl,-subsystem=console/gui/wince/...
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326 | Set type for PE (Windows) executables.
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327 |
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328 | @item -Wl,-[Ttext=# | section-alignment=# | file-alignment=# | image-base=# | stack=#]
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329 | Modify executable layout.
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330 |
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331 | @item -Wl,-Bsymbolic
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332 | Set DT_SYMBOLIC tag.
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333 |
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334 | @item -Wl,-(no-)whole-archive
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335 | Turn on/off linking of all objects in archives.
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336 |
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337 | @end table
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338 |
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339 | Debugger options:
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340 |
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341 | @table @option
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342 | @item -g
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343 | Generate run time debug information so that you get clear run time
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344 | error messages: @code{ test.c:68: in function 'test5()': dereferencing
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345 | invalid pointer} instead of the laconic @code{Segmentation
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346 | fault}.
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347 |
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348 | @item -b
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349 | Generate additional support code to check
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350 | memory allocations and array/pointer bounds. @option{-g} is implied. Note
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351 | that the generated code is slower and bigger in this case.
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352 |
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353 | Note: @option{-b} is only available on i386 when using libtcc for the moment.
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354 |
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355 | @item -bt N
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356 | Display N callers in stack traces. This is useful with @option{-g} or
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357 | @option{-b}.
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358 |
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359 | @end table
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360 |
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361 | Misc options:
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362 |
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363 | @table @option
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364 | @item -MD
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365 | Generate makefile fragment with dependencies.
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366 |
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367 | @item -MF depfile
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368 | Use @file{depfile} as output for -MD.
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369 |
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370 | @item -print-search-dirs
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371 | Print the configured installation directory and a list of library
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372 | and include directories tcc will search.
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373 |
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374 | @item -dumpversion
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375 | Print version.
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376 |
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377 | @end table
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378 |
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379 | Target specific options:
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380 |
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381 | @table @option
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382 | @item -mms-bitfields
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383 | Use an algorithm for bitfield alignment consistent with MSVC. Default is
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384 | gcc's algorithm.
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385 |
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386 | @item -mfloat-abi (ARM only)
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387 | Select the float ABI. Possible values: @code{softfp} and @code{hard}
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388 |
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389 | @item -mno-sse
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390 | Do not use sse registers on x86_64
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391 |
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392 | @item -m32, -m64
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393 | Pass command line to the i386/x86_64 cross compiler.
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394 |
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395 | @end table
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396 |
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397 | Note: GCC options @option{-Ox}, @option{-fx} and @option{-mx} are
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398 | ignored.
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399 | @c man end
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400 |
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401 | @c man begin ENVIRONMENT
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402 | Environment variables that affect how tcc operates.
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403 |
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404 | @table @option
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405 |
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406 | @item CPATH
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407 | @item C_INCLUDE_PATH
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408 | A colon-separated list of directories searched for include files,
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409 | directories given with @option{-I} are searched first.
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410 |
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411 | @item LIBRARY_PATH
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412 | A colon-separated list of directories searched for libraries for the
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413 | @option{-l} option, directories given with @option{-L} are searched first.
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414 |
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415 | @end table
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416 |
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417 | @c man end
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418 |
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419 | @ignore
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420 |
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421 | @setfilename tcc
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422 | @settitle Tiny C Compiler
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423 |
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424 | @c man begin SEEALSO
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425 | cpp(1),
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426 | gcc(1)
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427 | @c man end
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428 |
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429 | @c man begin AUTHOR
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430 | Fabrice Bellard
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431 | @c man end
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432 |
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433 | @end ignore
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434 |
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435 | @node Clang
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436 | @chapter C language support
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437 |
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438 | @section ANSI C
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439 |
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440 | TCC implements all the ANSI C standard, including structure bit fields
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441 | and floating point numbers (@code{long double}, @code{double}, and
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442 | @code{float} fully supported).
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443 |
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444 | @section ISOC99 extensions
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445 |
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446 | TCC implements many features of the new C standard: ISO C99. Currently
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447 | missing items are: complex and imaginary numbers.
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448 |
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449 | Currently implemented ISOC99 features:
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450 |
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451 | @itemize
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452 |
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453 | @item variable length arrays.
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454 |
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455 | @item 64 bit @code{long long} types are fully supported.
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456 |
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457 | @item The boolean type @code{_Bool} is supported.
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458 |
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459 | @item @code{__func__} is a string variable containing the current
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460 | function name.
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461 |
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462 | @item Variadic macros: @code{__VA_ARGS__} can be used for
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463 | function-like macros:
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464 | @example
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465 | #define dprintf(level, __VA_ARGS__) printf(__VA_ARGS__)
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466 | @end example
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467 |
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468 | @noindent
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469 | @code{dprintf} can then be used with a variable number of parameters.
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470 |
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471 | @item Declarations can appear anywhere in a block (as in C++).
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472 |
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473 | @item Array and struct/union elements can be initialized in any order by
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474 | using designators:
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475 | @example
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476 | struct @{ int x, y; @} st[10] = @{ [0].x = 1, [0].y = 2 @};
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477 |
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478 | int tab[10] = @{ 1, 2, [5] = 5, [9] = 9@};
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479 | @end example
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480 |
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481 | @item Compound initializers are supported:
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482 | @example
|
---|
483 | int *p = (int [])@{ 1, 2, 3 @};
|
---|
484 | @end example
|
---|
485 | to initialize a pointer pointing to an initialized array. The same
|
---|
486 | works for structures and strings.
|
---|
487 |
|
---|
488 | @item Hexadecimal floating point constants are supported:
|
---|
489 | @example
|
---|
490 | double d = 0x1234p10;
|
---|
491 | @end example
|
---|
492 |
|
---|
493 | @noindent
|
---|
494 | is the same as writing
|
---|
495 | @example
|
---|
496 | double d = 4771840.0;
|
---|
497 | @end example
|
---|
498 |
|
---|
499 | @item @code{inline} keyword is ignored.
|
---|
500 |
|
---|
501 | @item @code{restrict} keyword is ignored.
|
---|
502 | @end itemize
|
---|
503 |
|
---|
504 | @section GNU C extensions
|
---|
505 |
|
---|
506 | TCC implements some GNU C extensions:
|
---|
507 |
|
---|
508 | @itemize
|
---|
509 |
|
---|
510 | @item array designators can be used without '=':
|
---|
511 | @example
|
---|
512 | int a[10] = @{ [0] 1, [5] 2, 3, 4 @};
|
---|
513 | @end example
|
---|
514 |
|
---|
515 | @item Structure field designators can be a label:
|
---|
516 | @example
|
---|
517 | struct @{ int x, y; @} st = @{ x: 1, y: 1@};
|
---|
518 | @end example
|
---|
519 | instead of
|
---|
520 | @example
|
---|
521 | struct @{ int x, y; @} st = @{ .x = 1, .y = 1@};
|
---|
522 | @end example
|
---|
523 |
|
---|
524 | @item @code{\e} is ASCII character 27.
|
---|
525 |
|
---|
526 | @item case ranges : ranges can be used in @code{case}s:
|
---|
527 | @example
|
---|
528 | switch(a) @{
|
---|
529 | case 1 @dots{} 9:
|
---|
530 | printf("range 1 to 9\n");
|
---|
531 | break;
|
---|
532 | default:
|
---|
533 | printf("unexpected\n");
|
---|
534 | break;
|
---|
535 | @}
|
---|
536 | @end example
|
---|
537 |
|
---|
538 | @cindex aligned attribute
|
---|
539 | @cindex packed attribute
|
---|
540 | @cindex section attribute
|
---|
541 | @cindex unused attribute
|
---|
542 | @cindex cdecl attribute
|
---|
543 | @cindex stdcall attribute
|
---|
544 | @cindex regparm attribute
|
---|
545 | @cindex dllexport attribute
|
---|
546 |
|
---|
547 | @item The keyword @code{__attribute__} is handled to specify variable or
|
---|
548 | function attributes. The following attributes are supported:
|
---|
549 | @itemize
|
---|
550 |
|
---|
551 | @item @code{aligned(n)}: align a variable or a structure field to n bytes
|
---|
552 | (must be a power of two).
|
---|
553 |
|
---|
554 | @item @code{packed}: force alignment of a variable or a structure field to
|
---|
555 | 1.
|
---|
556 |
|
---|
557 | @item @code{section(name)}: generate function or data in assembly section
|
---|
558 | name (name is a string containing the section name) instead of the default
|
---|
559 | section.
|
---|
560 |
|
---|
561 | @item @code{unused}: specify that the variable or the function is unused.
|
---|
562 |
|
---|
563 | @item @code{cdecl}: use standard C calling convention (default).
|
---|
564 |
|
---|
565 | @item @code{stdcall}: use Pascal-like calling convention.
|
---|
566 |
|
---|
567 | @item @code{regparm(n)}: use fast i386 calling convention. @var{n} must be
|
---|
568 | between 1 and 3. The first @var{n} function parameters are respectively put in
|
---|
569 | registers @code{%eax}, @code{%edx} and @code{%ecx}.
|
---|
570 |
|
---|
571 | @item @code{dllexport}: export function from dll/executable (win32 only)
|
---|
572 |
|
---|
573 | @end itemize
|
---|
574 |
|
---|
575 | Here are some examples:
|
---|
576 | @example
|
---|
577 | int a __attribute__ ((aligned(8), section(".mysection")));
|
---|
578 | @end example
|
---|
579 |
|
---|
580 | @noindent
|
---|
581 | align variable @code{a} to 8 bytes and put it in section @code{.mysection}.
|
---|
582 |
|
---|
583 | @example
|
---|
584 | int my_add(int a, int b) __attribute__ ((section(".mycodesection")))
|
---|
585 | @{
|
---|
586 | return a + b;
|
---|
587 | @}
|
---|
588 | @end example
|
---|
589 |
|
---|
590 | @noindent
|
---|
591 | generate function @code{my_add} in section @code{.mycodesection}.
|
---|
592 |
|
---|
593 | @item GNU style variadic macros:
|
---|
594 | @example
|
---|
595 | #define dprintf(fmt, args@dots{}) printf(fmt, ## args)
|
---|
596 |
|
---|
597 | dprintf("no arg\n");
|
---|
598 | dprintf("one arg %d\n", 1);
|
---|
599 | @end example
|
---|
600 |
|
---|
601 | @item @code{__FUNCTION__} is interpreted as C99 @code{__func__}
|
---|
602 | (so it has not exactly the same semantics as string literal GNUC
|
---|
603 | where it is a string literal).
|
---|
604 |
|
---|
605 | @item The @code{__alignof__} keyword can be used as @code{sizeof}
|
---|
606 | to get the alignment of a type or an expression.
|
---|
607 |
|
---|
608 | @item The @code{typeof(x)} returns the type of @code{x}.
|
---|
609 | @code{x} is an expression or a type.
|
---|
610 |
|
---|
611 | @item Computed gotos: @code{&&label} returns a pointer of type
|
---|
612 | @code{void *} on the goto label @code{label}. @code{goto *expr} can be
|
---|
613 | used to jump on the pointer resulting from @code{expr}.
|
---|
614 |
|
---|
615 | @item Inline assembly with asm instruction:
|
---|
616 | @cindex inline assembly
|
---|
617 | @cindex assembly, inline
|
---|
618 | @cindex __asm__
|
---|
619 | @example
|
---|
620 | static inline void * my_memcpy(void * to, const void * from, size_t n)
|
---|
621 | @{
|
---|
622 | int d0, d1, d2;
|
---|
623 | __asm__ __volatile__(
|
---|
624 | "rep ; movsl\n\t"
|
---|
625 | "testb $2,%b4\n\t"
|
---|
626 | "je 1f\n\t"
|
---|
627 | "movsw\n"
|
---|
628 | "1:\ttestb $1,%b4\n\t"
|
---|
629 | "je 2f\n\t"
|
---|
630 | "movsb\n"
|
---|
631 | "2:"
|
---|
632 | : "=&c" (d0), "=&D" (d1), "=&S" (d2)
|
---|
633 | :"0" (n/4), "q" (n),"1" ((long) to),"2" ((long) from)
|
---|
634 | : "memory");
|
---|
635 | return (to);
|
---|
636 | @}
|
---|
637 | @end example
|
---|
638 |
|
---|
639 | @noindent
|
---|
640 | @cindex gas
|
---|
641 | TCC includes its own x86 inline assembler with a @code{gas}-like (GNU
|
---|
642 | assembler) syntax. No intermediate files are generated. GCC 3.x named
|
---|
643 | operands are supported.
|
---|
644 |
|
---|
645 | @item @code{__builtin_types_compatible_p()} and @code{__builtin_constant_p()}
|
---|
646 | are supported.
|
---|
647 |
|
---|
648 | @item @code{#pragma pack} is supported for win32 compatibility.
|
---|
649 |
|
---|
650 | @end itemize
|
---|
651 |
|
---|
652 | @section TinyCC extensions
|
---|
653 |
|
---|
654 | @itemize
|
---|
655 |
|
---|
656 | @item @code{__TINYC__} is a predefined macro to indicate that you use TCC.
|
---|
657 |
|
---|
658 | @item @code{#!} at the start of a line is ignored to allow scripting.
|
---|
659 |
|
---|
660 | @item Binary digits can be entered (@code{0b101} instead of
|
---|
661 | @code{5}).
|
---|
662 |
|
---|
663 | @item @code{__BOUNDS_CHECKING_ON} is defined if bound checking is activated.
|
---|
664 |
|
---|
665 | @end itemize
|
---|
666 |
|
---|
667 | @node asm
|
---|
668 | @chapter TinyCC Assembler
|
---|
669 |
|
---|
670 | Since version 0.9.16, TinyCC integrates its own assembler. TinyCC
|
---|
671 | assembler supports a gas-like syntax (GNU assembler). You can
|
---|
672 | deactivate assembler support if you want a smaller TinyCC executable
|
---|
673 | (the C compiler does not rely on the assembler).
|
---|
674 |
|
---|
675 | TinyCC Assembler is used to handle files with @file{.S} (C
|
---|
676 | preprocessed assembler) and @file{.s} extensions. It is also used to
|
---|
677 | handle the GNU inline assembler with the @code{asm} keyword.
|
---|
678 |
|
---|
679 | @section Syntax
|
---|
680 |
|
---|
681 | TinyCC Assembler supports most of the gas syntax. The tokens are the
|
---|
682 | same as C.
|
---|
683 |
|
---|
684 | @itemize
|
---|
685 |
|
---|
686 | @item C and C++ comments are supported.
|
---|
687 |
|
---|
688 | @item Identifiers are the same as C, so you cannot use '.' or '$'.
|
---|
689 |
|
---|
690 | @item Only 32 bit integer numbers are supported.
|
---|
691 |
|
---|
692 | @end itemize
|
---|
693 |
|
---|
694 | @section Expressions
|
---|
695 |
|
---|
696 | @itemize
|
---|
697 |
|
---|
698 | @item Integers in decimal, octal and hexa are supported.
|
---|
699 |
|
---|
700 | @item Unary operators: +, -, ~.
|
---|
701 |
|
---|
702 | @item Binary operators in decreasing priority order:
|
---|
703 |
|
---|
704 | @enumerate
|
---|
705 | @item *, /, %
|
---|
706 | @item &, |, ^
|
---|
707 | @item +, -
|
---|
708 | @end enumerate
|
---|
709 |
|
---|
710 | @item A value is either an absolute number or a label plus an offset.
|
---|
711 | All operators accept absolute values except '+' and '-'. '+' or '-' can be
|
---|
712 | used to add an offset to a label. '-' supports two labels only if they
|
---|
713 | are the same or if they are both defined and in the same section.
|
---|
714 |
|
---|
715 | @end itemize
|
---|
716 |
|
---|
717 | @section Labels
|
---|
718 |
|
---|
719 | @itemize
|
---|
720 |
|
---|
721 | @item All labels are considered as local, except undefined ones.
|
---|
722 |
|
---|
723 | @item Numeric labels can be used as local @code{gas}-like labels.
|
---|
724 | They can be defined several times in the same source. Use 'b'
|
---|
725 | (backward) or 'f' (forward) as suffix to reference them:
|
---|
726 |
|
---|
727 | @example
|
---|
728 | 1:
|
---|
729 | jmp 1b /* jump to '1' label before */
|
---|
730 | jmp 1f /* jump to '1' label after */
|
---|
731 | 1:
|
---|
732 | @end example
|
---|
733 |
|
---|
734 | @end itemize
|
---|
735 |
|
---|
736 | @section Directives
|
---|
737 | @cindex assembler directives
|
---|
738 | @cindex directives, assembler
|
---|
739 | @cindex align directive
|
---|
740 | @cindex skip directive
|
---|
741 | @cindex space directive
|
---|
742 | @cindex byte directive
|
---|
743 | @cindex word directive
|
---|
744 | @cindex short directive
|
---|
745 | @cindex int directive
|
---|
746 | @cindex long directive
|
---|
747 | @cindex quad directive
|
---|
748 | @cindex globl directive
|
---|
749 | @cindex global directive
|
---|
750 | @cindex section directive
|
---|
751 | @cindex text directive
|
---|
752 | @cindex data directive
|
---|
753 | @cindex bss directive
|
---|
754 | @cindex fill directive
|
---|
755 | @cindex org directive
|
---|
756 | @cindex previous directive
|
---|
757 | @cindex string directive
|
---|
758 | @cindex asciz directive
|
---|
759 | @cindex ascii directive
|
---|
760 |
|
---|
761 | All directives are preceded by a '.'. The following directives are
|
---|
762 | supported:
|
---|
763 |
|
---|
764 | @itemize
|
---|
765 | @item .align n[,value]
|
---|
766 | @item .skip n[,value]
|
---|
767 | @item .space n[,value]
|
---|
768 | @item .byte value1[,...]
|
---|
769 | @item .word value1[,...]
|
---|
770 | @item .short value1[,...]
|
---|
771 | @item .int value1[,...]
|
---|
772 | @item .long value1[,...]
|
---|
773 | @item .quad immediate_value1[,...]
|
---|
774 | @item .globl symbol
|
---|
775 | @item .global symbol
|
---|
776 | @item .section section
|
---|
777 | @item .text
|
---|
778 | @item .data
|
---|
779 | @item .bss
|
---|
780 | @item .fill repeat[,size[,value]]
|
---|
781 | @item .org n
|
---|
782 | @item .previous
|
---|
783 | @item .string string[,...]
|
---|
784 | @item .asciz string[,...]
|
---|
785 | @item .ascii string[,...]
|
---|
786 | @end itemize
|
---|
787 |
|
---|
788 | @section X86 Assembler
|
---|
789 | @cindex assembler
|
---|
790 |
|
---|
791 | All X86 opcodes are supported. Only ATT syntax is supported (source
|
---|
792 | then destination operand order). If no size suffix is given, TinyCC
|
---|
793 | tries to guess it from the operand sizes.
|
---|
794 |
|
---|
795 | Currently, MMX opcodes are supported but not SSE ones.
|
---|
796 |
|
---|
797 | @node linker
|
---|
798 | @chapter TinyCC Linker
|
---|
799 | @cindex linker
|
---|
800 |
|
---|
801 | @section ELF file generation
|
---|
802 | @cindex ELF
|
---|
803 |
|
---|
804 | TCC can directly output relocatable ELF files (object files),
|
---|
805 | executable ELF files and dynamic ELF libraries without relying on an
|
---|
806 | external linker.
|
---|
807 |
|
---|
808 | Dynamic ELF libraries can be output but the C compiler does not generate
|
---|
809 | position independent code (PIC). It means that the dynamic library
|
---|
810 | code generated by TCC cannot be factorized among processes yet.
|
---|
811 |
|
---|
812 | TCC linker eliminates unreferenced object code in libraries. A single pass is
|
---|
813 | done on the object and library list, so the order in which object files and
|
---|
814 | libraries are specified is important (same constraint as GNU ld). No grouping
|
---|
815 | options (@option{--start-group} and @option{--end-group}) are supported.
|
---|
816 |
|
---|
817 | @section ELF file loader
|
---|
818 |
|
---|
819 | TCC can load ELF object files, archives (.a files) and dynamic
|
---|
820 | libraries (.so).
|
---|
821 |
|
---|
822 | @section PE-i386 file generation
|
---|
823 | @cindex PE-i386
|
---|
824 |
|
---|
825 | TCC for Windows supports the native Win32 executable file format (PE-i386). It
|
---|
826 | generates EXE files (console and gui) and DLL files.
|
---|
827 |
|
---|
828 | For usage on Windows, see also tcc-win32.txt.
|
---|
829 |
|
---|
830 | @section GNU Linker Scripts
|
---|
831 | @cindex scripts, linker
|
---|
832 | @cindex linker scripts
|
---|
833 | @cindex GROUP, linker command
|
---|
834 | @cindex FILE, linker command
|
---|
835 | @cindex OUTPUT_FORMAT, linker command
|
---|
836 | @cindex TARGET, linker command
|
---|
837 |
|
---|
838 | Because on many Linux systems some dynamic libraries (such as
|
---|
839 | @file{/usr/lib/libc.so}) are in fact GNU ld link scripts (horrible!),
|
---|
840 | the TCC linker also supports a subset of GNU ld scripts.
|
---|
841 |
|
---|
842 | The @code{GROUP} and @code{FILE} commands are supported. @code{OUTPUT_FORMAT}
|
---|
843 | and @code{TARGET} are ignored.
|
---|
844 |
|
---|
845 | Example from @file{/usr/lib/libc.so}:
|
---|
846 | @example
|
---|
847 | /* GNU ld script
|
---|
848 | Use the shared library, but some functions are only in
|
---|
849 | the static library, so try that secondarily. */
|
---|
850 | GROUP ( /lib/libc.so.6 /usr/lib/libc_nonshared.a )
|
---|
851 | @end example
|
---|
852 |
|
---|
853 | @node Bounds
|
---|
854 | @chapter TinyCC Memory and Bound checks
|
---|
855 | @cindex bound checks
|
---|
856 | @cindex memory checks
|
---|
857 |
|
---|
858 | This feature is activated with the @option{-b} (@pxref{Invoke}).
|
---|
859 |
|
---|
860 | Note that pointer size is @emph{unchanged} and that code generated
|
---|
861 | with bound checks is @emph{fully compatible} with unchecked
|
---|
862 | code. When a pointer comes from unchecked code, it is assumed to be
|
---|
863 | valid. Even very obscure C code with casts should work correctly.
|
---|
864 |
|
---|
865 | For more information about the ideas behind this method, see
|
---|
866 | @url{http://www.doc.ic.ac.uk/~phjk/BoundsChecking.html}.
|
---|
867 |
|
---|
868 | Here are some examples of caught errors:
|
---|
869 |
|
---|
870 | @table @asis
|
---|
871 |
|
---|
872 | @item Invalid range with standard string function:
|
---|
873 | @example
|
---|
874 | @{
|
---|
875 | char tab[10];
|
---|
876 | memset(tab, 0, 11);
|
---|
877 | @}
|
---|
878 | @end example
|
---|
879 |
|
---|
880 | @item Out of bounds-error in global or local arrays:
|
---|
881 | @example
|
---|
882 | @{
|
---|
883 | int tab[10];
|
---|
884 | for(i=0;i<11;i++) @{
|
---|
885 | sum += tab[i];
|
---|
886 | @}
|
---|
887 | @}
|
---|
888 | @end example
|
---|
889 |
|
---|
890 | @item Out of bounds-error in malloc'ed data:
|
---|
891 | @example
|
---|
892 | @{
|
---|
893 | int *tab;
|
---|
894 | tab = malloc(20 * sizeof(int));
|
---|
895 | for(i=0;i<21;i++) @{
|
---|
896 | sum += tab4[i];
|
---|
897 | @}
|
---|
898 | free(tab);
|
---|
899 | @}
|
---|
900 | @end example
|
---|
901 |
|
---|
902 | @item Access of freed memory:
|
---|
903 | @example
|
---|
904 | @{
|
---|
905 | int *tab;
|
---|
906 | tab = malloc(20 * sizeof(int));
|
---|
907 | free(tab);
|
---|
908 | for(i=0;i<20;i++) @{
|
---|
909 | sum += tab4[i];
|
---|
910 | @}
|
---|
911 | @}
|
---|
912 | @end example
|
---|
913 |
|
---|
914 | @item Double free:
|
---|
915 | @example
|
---|
916 | @{
|
---|
917 | int *tab;
|
---|
918 | tab = malloc(20 * sizeof(int));
|
---|
919 | free(tab);
|
---|
920 | free(tab);
|
---|
921 | @}
|
---|
922 | @end example
|
---|
923 |
|
---|
924 | @end table
|
---|
925 |
|
---|
926 | @node Libtcc
|
---|
927 | @chapter The @code{libtcc} library
|
---|
928 |
|
---|
929 | The @code{libtcc} library enables you to use TCC as a backend for
|
---|
930 | dynamic code generation.
|
---|
931 |
|
---|
932 | Read the @file{libtcc.h} to have an overview of the API. Read
|
---|
933 | @file{libtcc_test.c} to have a very simple example.
|
---|
934 |
|
---|
935 | The idea consists in giving a C string containing the program you want
|
---|
936 | to compile directly to @code{libtcc}. Then you can access to any global
|
---|
937 | symbol (function or variable) defined.
|
---|
938 |
|
---|
939 | @node devel
|
---|
940 | @chapter Developer's guide
|
---|
941 |
|
---|
942 | This chapter gives some hints to understand how TCC works. You can skip
|
---|
943 | it if you do not intend to modify the TCC code.
|
---|
944 |
|
---|
945 | @section File reading
|
---|
946 |
|
---|
947 | The @code{BufferedFile} structure contains the context needed to read a
|
---|
948 | file, including the current line number. @code{tcc_open()} opens a new
|
---|
949 | file and @code{tcc_close()} closes it. @code{inp()} returns the next
|
---|
950 | character.
|
---|
951 |
|
---|
952 | @section Lexer
|
---|
953 |
|
---|
954 | @code{next()} reads the next token in the current
|
---|
955 | file. @code{next_nomacro()} reads the next token without macro
|
---|
956 | expansion.
|
---|
957 |
|
---|
958 | @code{tok} contains the current token (see @code{TOK_xxx})
|
---|
959 | constants. Identifiers and keywords are also keywords. @code{tokc}
|
---|
960 | contains additional infos about the token (for example a constant value
|
---|
961 | if number or string token).
|
---|
962 |
|
---|
963 | @section Parser
|
---|
964 |
|
---|
965 | The parser is hardcoded (yacc is not necessary). It does only one pass,
|
---|
966 | except:
|
---|
967 |
|
---|
968 | @itemize
|
---|
969 |
|
---|
970 | @item For initialized arrays with unknown size, a first pass
|
---|
971 | is done to count the number of elements.
|
---|
972 |
|
---|
973 | @item For architectures where arguments are evaluated in
|
---|
974 | reverse order, a first pass is done to reverse the argument order.
|
---|
975 |
|
---|
976 | @end itemize
|
---|
977 |
|
---|
978 | @section Types
|
---|
979 |
|
---|
980 | The types are stored in a single 'int' variable. It was chosen in the
|
---|
981 | first stages of development when tcc was much simpler. Now, it may not
|
---|
982 | be the best solution.
|
---|
983 |
|
---|
984 | @example
|
---|
985 | #define VT_INT 0 /* integer type */
|
---|
986 | #define VT_BYTE 1 /* signed byte type */
|
---|
987 | #define VT_SHORT 2 /* short type */
|
---|
988 | #define VT_VOID 3 /* void type */
|
---|
989 | #define VT_PTR 4 /* pointer */
|
---|
990 | #define VT_ENUM 5 /* enum definition */
|
---|
991 | #define VT_FUNC 6 /* function type */
|
---|
992 | #define VT_STRUCT 7 /* struct/union definition */
|
---|
993 | #define VT_FLOAT 8 /* IEEE float */
|
---|
994 | #define VT_DOUBLE 9 /* IEEE double */
|
---|
995 | #define VT_LDOUBLE 10 /* IEEE long double */
|
---|
996 | #define VT_BOOL 11 /* ISOC99 boolean type */
|
---|
997 | #define VT_LLONG 12 /* 64 bit integer */
|
---|
998 | #define VT_LONG 13 /* long integer (NEVER USED as type, only
|
---|
999 | during parsing) */
|
---|
1000 | #define VT_BTYPE 0x000f /* mask for basic type */
|
---|
1001 | #define VT_UNSIGNED 0x0010 /* unsigned type */
|
---|
1002 | #define VT_ARRAY 0x0020 /* array type (also has VT_PTR) */
|
---|
1003 | #define VT_VLA 0x20000 /* VLA type (also has VT_PTR and VT_ARRAY) */
|
---|
1004 | #define VT_BITFIELD 0x0040 /* bitfield modifier */
|
---|
1005 | #define VT_CONSTANT 0x0800 /* const modifier */
|
---|
1006 | #define VT_VOLATILE 0x1000 /* volatile modifier */
|
---|
1007 | #define VT_DEFSIGN 0x2000 /* signed type */
|
---|
1008 |
|
---|
1009 | #define VT_STRUCT_SHIFT 18 /* structure/enum name shift (14 bits left) */
|
---|
1010 | @end example
|
---|
1011 |
|
---|
1012 | When a reference to another type is needed (for pointers, functions and
|
---|
1013 | structures), the @code{32 - VT_STRUCT_SHIFT} high order bits are used to
|
---|
1014 | store an identifier reference.
|
---|
1015 |
|
---|
1016 | The @code{VT_UNSIGNED} flag can be set for chars, shorts, ints and long
|
---|
1017 | longs.
|
---|
1018 |
|
---|
1019 | Arrays are considered as pointers @code{VT_PTR} with the flag
|
---|
1020 | @code{VT_ARRAY} set. Variable length arrays are considered as special
|
---|
1021 | arrays and have flag @code{VT_VLA} set instead of @code{VT_ARRAY}.
|
---|
1022 |
|
---|
1023 | The @code{VT_BITFIELD} flag can be set for chars, shorts, ints and long
|
---|
1024 | longs. If it is set, then the bitfield position is stored from bits
|
---|
1025 | VT_STRUCT_SHIFT to VT_STRUCT_SHIFT + 5 and the bit field size is stored
|
---|
1026 | from bits VT_STRUCT_SHIFT + 6 to VT_STRUCT_SHIFT + 11.
|
---|
1027 |
|
---|
1028 | @code{VT_LONG} is never used except during parsing.
|
---|
1029 |
|
---|
1030 | During parsing, the storage of an object is also stored in the type
|
---|
1031 | integer:
|
---|
1032 |
|
---|
1033 | @example
|
---|
1034 | #define VT_EXTERN 0x00000080 /* extern definition */
|
---|
1035 | #define VT_STATIC 0x00000100 /* static variable */
|
---|
1036 | #define VT_TYPEDEF 0x00000200 /* typedef definition */
|
---|
1037 | #define VT_INLINE 0x00000400 /* inline definition */
|
---|
1038 | #define VT_IMPORT 0x00004000 /* win32: extern data imported from dll */
|
---|
1039 | #define VT_EXPORT 0x00008000 /* win32: data exported from dll */
|
---|
1040 | #define VT_WEAK 0x00010000 /* win32: data exported from dll */
|
---|
1041 | @end example
|
---|
1042 |
|
---|
1043 | @section Symbols
|
---|
1044 |
|
---|
1045 | All symbols are stored in hashed symbol stacks. Each symbol stack
|
---|
1046 | contains @code{Sym} structures.
|
---|
1047 |
|
---|
1048 | @code{Sym.v} contains the symbol name (remember
|
---|
1049 | an identifier is also a token, so a string is never necessary to store
|
---|
1050 | it). @code{Sym.t} gives the type of the symbol. @code{Sym.r} is usually
|
---|
1051 | the register in which the corresponding variable is stored. @code{Sym.c} is
|
---|
1052 | usually a constant associated to the symbol like its address for normal
|
---|
1053 | symbols, and the number of entries for symbols representing arrays.
|
---|
1054 | Variable length array types use @code{Sym.c} as a location on the stack
|
---|
1055 | which holds the runtime sizeof for the type.
|
---|
1056 |
|
---|
1057 | Four main symbol stacks are defined:
|
---|
1058 |
|
---|
1059 | @table @code
|
---|
1060 |
|
---|
1061 | @item define_stack
|
---|
1062 | for the macros (@code{#define}s).
|
---|
1063 |
|
---|
1064 | @item global_stack
|
---|
1065 | for the global variables, functions and types.
|
---|
1066 |
|
---|
1067 | @item local_stack
|
---|
1068 | for the local variables, functions and types.
|
---|
1069 |
|
---|
1070 | @item global_label_stack
|
---|
1071 | for the local labels (for @code{goto}).
|
---|
1072 |
|
---|
1073 | @item label_stack
|
---|
1074 | for GCC block local labels (see the @code{__label__} keyword).
|
---|
1075 |
|
---|
1076 | @end table
|
---|
1077 |
|
---|
1078 | @code{sym_push()} is used to add a new symbol in the local symbol
|
---|
1079 | stack. If no local symbol stack is active, it is added in the global
|
---|
1080 | symbol stack.
|
---|
1081 |
|
---|
1082 | @code{sym_pop(st,b)} pops symbols from the symbol stack @var{st} until
|
---|
1083 | the symbol @var{b} is on the top of stack. If @var{b} is NULL, the stack
|
---|
1084 | is emptied.
|
---|
1085 |
|
---|
1086 | @code{sym_find(v)} return the symbol associated to the identifier
|
---|
1087 | @var{v}. The local stack is searched first from top to bottom, then the
|
---|
1088 | global stack.
|
---|
1089 |
|
---|
1090 | @section Sections
|
---|
1091 |
|
---|
1092 | The generated code and data are written in sections. The structure
|
---|
1093 | @code{Section} contains all the necessary information for a given
|
---|
1094 | section. @code{new_section()} creates a new section. ELF file semantics
|
---|
1095 | is assumed for each section.
|
---|
1096 |
|
---|
1097 | The following sections are predefined:
|
---|
1098 |
|
---|
1099 | @table @code
|
---|
1100 |
|
---|
1101 | @item text_section
|
---|
1102 | is the section containing the generated code. @var{ind} contains the
|
---|
1103 | current position in the code section.
|
---|
1104 |
|
---|
1105 | @item data_section
|
---|
1106 | contains initialized data
|
---|
1107 |
|
---|
1108 | @item bss_section
|
---|
1109 | contains uninitialized data
|
---|
1110 |
|
---|
1111 | @item bounds_section
|
---|
1112 | @itemx lbounds_section
|
---|
1113 | are used when bound checking is activated
|
---|
1114 |
|
---|
1115 | @item stab_section
|
---|
1116 | @itemx stabstr_section
|
---|
1117 | are used when debugging is active to store debug information
|
---|
1118 |
|
---|
1119 | @item symtab_section
|
---|
1120 | @itemx strtab_section
|
---|
1121 | contain the exported symbols (currently only used for debugging).
|
---|
1122 |
|
---|
1123 | @end table
|
---|
1124 |
|
---|
1125 | @section Code generation
|
---|
1126 | @cindex code generation
|
---|
1127 |
|
---|
1128 | @subsection Introduction
|
---|
1129 |
|
---|
1130 | The TCC code generator directly generates linked binary code in one
|
---|
1131 | pass. It is rather unusual these days (see gcc for example which
|
---|
1132 | generates text assembly), but it can be very fast and surprisingly
|
---|
1133 | little complicated.
|
---|
1134 |
|
---|
1135 | The TCC code generator is register based. Optimization is only done at
|
---|
1136 | the expression level. No intermediate representation of expression is
|
---|
1137 | kept except the current values stored in the @emph{value stack}.
|
---|
1138 |
|
---|
1139 | On x86, three temporary registers are used. When more registers are
|
---|
1140 | needed, one register is spilled into a new temporary variable on the stack.
|
---|
1141 |
|
---|
1142 | @subsection The value stack
|
---|
1143 | @cindex value stack, introduction
|
---|
1144 |
|
---|
1145 | When an expression is parsed, its value is pushed on the value stack
|
---|
1146 | (@var{vstack}). The top of the value stack is @var{vtop}. Each value
|
---|
1147 | stack entry is the structure @code{SValue}.
|
---|
1148 |
|
---|
1149 | @code{SValue.t} is the type. @code{SValue.r} indicates how the value is
|
---|
1150 | currently stored in the generated code. It is usually a CPU register
|
---|
1151 | index (@code{REG_xxx} constants), but additional values and flags are
|
---|
1152 | defined:
|
---|
1153 |
|
---|
1154 | @example
|
---|
1155 | #define VT_CONST 0x00f0
|
---|
1156 | #define VT_LLOCAL 0x00f1
|
---|
1157 | #define VT_LOCAL 0x00f2
|
---|
1158 | #define VT_CMP 0x00f3
|
---|
1159 | #define VT_JMP 0x00f4
|
---|
1160 | #define VT_JMPI 0x00f5
|
---|
1161 | #define VT_LVAL 0x0100
|
---|
1162 | #define VT_SYM 0x0200
|
---|
1163 | #define VT_MUSTCAST 0x0400
|
---|
1164 | #define VT_MUSTBOUND 0x0800
|
---|
1165 | #define VT_BOUNDED 0x8000
|
---|
1166 | #define VT_LVAL_BYTE 0x1000
|
---|
1167 | #define VT_LVAL_SHORT 0x2000
|
---|
1168 | #define VT_LVAL_UNSIGNED 0x4000
|
---|
1169 | #define VT_LVAL_TYPE (VT_LVAL_BYTE | VT_LVAL_SHORT | VT_LVAL_UNSIGNED)
|
---|
1170 | @end example
|
---|
1171 |
|
---|
1172 | @table @code
|
---|
1173 |
|
---|
1174 | @item VT_CONST
|
---|
1175 | indicates that the value is a constant. It is stored in the union
|
---|
1176 | @code{SValue.c}, depending on its type.
|
---|
1177 |
|
---|
1178 | @item VT_LOCAL
|
---|
1179 | indicates a local variable pointer at offset @code{SValue.c.i} in the
|
---|
1180 | stack.
|
---|
1181 |
|
---|
1182 | @item VT_CMP
|
---|
1183 | indicates that the value is actually stored in the CPU flags (i.e. the
|
---|
1184 | value is the consequence of a test). The value is either 0 or 1. The
|
---|
1185 | actual CPU flags used is indicated in @code{SValue.c.i}.
|
---|
1186 |
|
---|
1187 | If any code is generated which destroys the CPU flags, this value MUST be
|
---|
1188 | put in a normal register.
|
---|
1189 |
|
---|
1190 | @item VT_JMP
|
---|
1191 | @itemx VT_JMPI
|
---|
1192 | indicates that the value is the consequence of a conditional jump. For VT_JMP,
|
---|
1193 | it is 1 if the jump is taken, 0 otherwise. For VT_JMPI it is inverted.
|
---|
1194 |
|
---|
1195 | These values are used to compile the @code{||} and @code{&&} logical
|
---|
1196 | operators.
|
---|
1197 |
|
---|
1198 | If any code is generated, this value MUST be put in a normal
|
---|
1199 | register. Otherwise, the generated code won't be executed if the jump is
|
---|
1200 | taken.
|
---|
1201 |
|
---|
1202 | @item VT_LVAL
|
---|
1203 | is a flag indicating that the value is actually an lvalue (left value of
|
---|
1204 | an assignment). It means that the value stored is actually a pointer to
|
---|
1205 | the wanted value.
|
---|
1206 |
|
---|
1207 | Understanding the use @code{VT_LVAL} is very important if you want to
|
---|
1208 | understand how TCC works.
|
---|
1209 |
|
---|
1210 | @item VT_LVAL_BYTE
|
---|
1211 | @itemx VT_LVAL_SHORT
|
---|
1212 | @itemx VT_LVAL_UNSIGNED
|
---|
1213 | if the lvalue has an integer type, then these flags give its real
|
---|
1214 | type. The type alone is not enough in case of cast optimisations.
|
---|
1215 |
|
---|
1216 | @item VT_LLOCAL
|
---|
1217 | is a saved lvalue on the stack. @code{VT_LVAL} must also be set with
|
---|
1218 | @code{VT_LLOCAL}. @code{VT_LLOCAL} can arise when a @code{VT_LVAL} in
|
---|
1219 | a register has to be saved to the stack, or it can come from an
|
---|
1220 | architecture-specific calling convention.
|
---|
1221 |
|
---|
1222 | @item VT_MUSTCAST
|
---|
1223 | indicates that a cast to the value type must be performed if the value
|
---|
1224 | is used (lazy casting).
|
---|
1225 |
|
---|
1226 | @item VT_SYM
|
---|
1227 | indicates that the symbol @code{SValue.sym} must be added to the constant.
|
---|
1228 |
|
---|
1229 | @item VT_MUSTBOUND
|
---|
1230 | @itemx VT_BOUNDED
|
---|
1231 | are only used for optional bound checking.
|
---|
1232 |
|
---|
1233 | @end table
|
---|
1234 |
|
---|
1235 | @subsection Manipulating the value stack
|
---|
1236 | @cindex value stack
|
---|
1237 |
|
---|
1238 | @code{vsetc()} and @code{vset()} pushes a new value on the value
|
---|
1239 | stack. If the previous @var{vtop} was stored in a very unsafe place(for
|
---|
1240 | example in the CPU flags), then some code is generated to put the
|
---|
1241 | previous @var{vtop} in a safe storage.
|
---|
1242 |
|
---|
1243 | @code{vpop()} pops @var{vtop}. In some cases, it also generates cleanup
|
---|
1244 | code (for example if stacked floating point registers are used as on
|
---|
1245 | x86).
|
---|
1246 |
|
---|
1247 | The @code{gv(rc)} function generates code to evaluate @var{vtop} (the
|
---|
1248 | top value of the stack) into registers. @var{rc} selects in which
|
---|
1249 | register class the value should be put. @code{gv()} is the @emph{most
|
---|
1250 | important function} of the code generator.
|
---|
1251 |
|
---|
1252 | @code{gv2()} is the same as @code{gv()} but for the top two stack
|
---|
1253 | entries.
|
---|
1254 |
|
---|
1255 | @subsection CPU dependent code generation
|
---|
1256 | @cindex CPU dependent
|
---|
1257 | See the @file{i386-gen.c} file to have an example.
|
---|
1258 |
|
---|
1259 | @table @code
|
---|
1260 |
|
---|
1261 | @item load()
|
---|
1262 | must generate the code needed to load a stack value into a register.
|
---|
1263 |
|
---|
1264 | @item store()
|
---|
1265 | must generate the code needed to store a register into a stack value
|
---|
1266 | lvalue.
|
---|
1267 |
|
---|
1268 | @item gfunc_start()
|
---|
1269 | @itemx gfunc_param()
|
---|
1270 | @itemx gfunc_call()
|
---|
1271 | should generate a function call
|
---|
1272 |
|
---|
1273 | @item gfunc_prolog()
|
---|
1274 | @itemx gfunc_epilog()
|
---|
1275 | should generate a function prolog/epilog.
|
---|
1276 |
|
---|
1277 | @item gen_opi(op)
|
---|
1278 | must generate the binary integer operation @var{op} on the two top
|
---|
1279 | entries of the stack which are guaranteed to contain integer types.
|
---|
1280 |
|
---|
1281 | The result value should be put on the stack.
|
---|
1282 |
|
---|
1283 | @item gen_opf(op)
|
---|
1284 | same as @code{gen_opi()} for floating point operations. The two top
|
---|
1285 | entries of the stack are guaranteed to contain floating point values of
|
---|
1286 | same types.
|
---|
1287 |
|
---|
1288 | @item gen_cvt_itof()
|
---|
1289 | integer to floating point conversion.
|
---|
1290 |
|
---|
1291 | @item gen_cvt_ftoi()
|
---|
1292 | floating point to integer conversion.
|
---|
1293 |
|
---|
1294 | @item gen_cvt_ftof()
|
---|
1295 | floating point to floating point of different size conversion.
|
---|
1296 |
|
---|
1297 | @item gen_bounded_ptr_add()
|
---|
1298 | @item gen_bounded_ptr_deref()
|
---|
1299 | are only used for bounds checking.
|
---|
1300 |
|
---|
1301 | @end table
|
---|
1302 |
|
---|
1303 | @section Optimizations done
|
---|
1304 | @cindex optimizations
|
---|
1305 | @cindex constant propagation
|
---|
1306 | @cindex strength reduction
|
---|
1307 | @cindex comparison operators
|
---|
1308 | @cindex caching processor flags
|
---|
1309 | @cindex flags, caching
|
---|
1310 | @cindex jump optimization
|
---|
1311 | Constant propagation is done for all operations. Multiplications and
|
---|
1312 | divisions are optimized to shifts when appropriate. Comparison
|
---|
1313 | operators are optimized by maintaining a special cache for the
|
---|
1314 | processor flags. &&, || and ! are optimized by maintaining a special
|
---|
1315 | 'jump target' value. No other jump optimization is currently performed
|
---|
1316 | because it would require to store the code in a more abstract fashion.
|
---|
1317 |
|
---|
1318 | @unnumbered Concept Index
|
---|
1319 | @printindex cp
|
---|
1320 |
|
---|
1321 | @bye
|
---|
1322 |
|
---|
1323 | @c Local variables:
|
---|
1324 | @c fill-column: 78
|
---|
1325 | @c texinfo-column-for-description: 32
|
---|
1326 | @c End:
|
---|