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| <title>GNU Compiler Collection (GCC) Internals: Machine Desc</title> |
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| Next: <a href="Target-Macros.html#Target-Macros" accesskey="n" rel="next">Target Macros</a>, Previous: <a href="Loop-Analysis-and-Representation.html#Loop-Analysis-and-Representation" accesskey="p" rel="prev">Loop Analysis and Representation</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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| <h2 class="chapter">16 Machine Descriptions</h2> |
| <a name="index-machine-descriptions"></a> |
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| <p>A machine description has two parts: a file of instruction patterns |
| (<samp>.md</samp> file) and a C header file of macro definitions. |
| </p> |
| <p>The <samp>.md</samp> file for a target machine contains a pattern for each |
| instruction that the target machine supports (or at least each instruction |
| that is worth telling the compiler about). It may also contain comments. |
| A semicolon causes the rest of the line to be a comment, unless the semicolon |
| is inside a quoted string. |
| </p> |
| <p>See the next chapter for information on the C header file. |
| </p> |
| <table class="menu" border="0" cellspacing="0"> |
| <tr><td align="left" valign="top">• <a href="Overview.html#Overview" accesskey="1">Overview</a>:</td><td> </td><td align="left" valign="top">How the machine description is used. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Patterns.html#Patterns" accesskey="2">Patterns</a>:</td><td> </td><td align="left" valign="top">How to write instruction patterns. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Example.html#Example" accesskey="3">Example</a>:</td><td> </td><td align="left" valign="top">An explained example of a <code>define_insn</code> pattern. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="RTL-Template.html#RTL-Template" accesskey="4">RTL Template</a>:</td><td> </td><td align="left" valign="top">The RTL template defines what insns match a pattern. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Output-Template.html#Output-Template" accesskey="5">Output Template</a>:</td><td> </td><td align="left" valign="top">The output template says how to make assembler code |
| from such an insn. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Output-Statement.html#Output-Statement" accesskey="6">Output Statement</a>:</td><td> </td><td align="left" valign="top">For more generality, write C code to output |
| the assembler code. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Predicates.html#Predicates" accesskey="7">Predicates</a>:</td><td> </td><td align="left" valign="top">Controlling what kinds of operands can be used |
| for an insn. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Constraints.html#Constraints" accesskey="8">Constraints</a>:</td><td> </td><td align="left" valign="top">Fine-tuning operand selection. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Standard-Names.html#Standard-Names" accesskey="9">Standard Names</a>:</td><td> </td><td align="left" valign="top">Names mark patterns to use for code generation. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Pattern-Ordering.html#Pattern-Ordering">Pattern Ordering</a>:</td><td> </td><td align="left" valign="top">When the order of patterns makes a difference. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Dependent-Patterns.html#Dependent-Patterns">Dependent Patterns</a>:</td><td> </td><td align="left" valign="top">Having one pattern may make you need another. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Jump-Patterns.html#Jump-Patterns">Jump Patterns</a>:</td><td> </td><td align="left" valign="top">Special considerations for patterns for jump insns. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Looping-Patterns.html#Looping-Patterns">Looping Patterns</a>:</td><td> </td><td align="left" valign="top">How to define patterns for special looping insns. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Insn-Canonicalizations.html#Insn-Canonicalizations">Insn Canonicalizations</a>:</td><td> </td><td align="left" valign="top">Canonicalization of Instructions |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Expander-Definitions.html#Expander-Definitions">Expander Definitions</a>:</td><td> </td><td align="left" valign="top">Generating a sequence of several RTL insns |
| for a standard operation. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Insn-Splitting.html#Insn-Splitting">Insn Splitting</a>:</td><td> </td><td align="left" valign="top">Splitting Instructions into Multiple Instructions. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Including-Patterns.html#Including-Patterns">Including Patterns</a>:</td><td> </td><td align="left" valign="top">Including Patterns in Machine Descriptions. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Peephole-Definitions.html#Peephole-Definitions">Peephole Definitions</a>:</td><td> </td><td align="left" valign="top">Defining machine-specific peephole optimizations. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Insn-Attributes.html#Insn-Attributes">Insn Attributes</a>:</td><td> </td><td align="left" valign="top">Specifying the value of attributes for generated insns. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Conditional-Execution.html#Conditional-Execution">Conditional Execution</a>:</td><td> </td><td align="left" valign="top">Generating <code>define_insn</code> patterns for |
| predication. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Define-Subst.html#Define-Subst">Define Subst</a>:</td><td> </td><td align="left" valign="top">Generating <code>define_insn</code> and <code>define_expand</code> |
| patterns from other patterns. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Constant-Definitions.html#Constant-Definitions">Constant Definitions</a>:</td><td> </td><td align="left" valign="top">Defining symbolic constants that can be used in the |
| md file. |
| </td></tr> |
| <tr><td align="left" valign="top">• <a href="Iterators.html#Iterators">Iterators</a>:</td><td> </td><td align="left" valign="top">Using iterators to generate patterns from a template. |
| </td></tr> |
| </table> |
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| Next: <a href="Target-Macros.html#Target-Macros" accesskey="n" rel="next">Target Macros</a>, Previous: <a href="Loop-Analysis-and-Representation.html#Loop-Analysis-and-Representation" accesskey="p" rel="prev">Loop Analysis and Representation</a>, Up: <a href="index.html#Top" accesskey="u" rel="up">Top</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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