Machine Desc

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Machine Descriptions
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   A machine description has two parts: a file of instruction patterns
(`.md' file) and a C header file of macro definitions.

   The `.md' 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.

   See the next chapter for information on the C header file.

Patterns: How to write instruction patterns.
Example: An explained example of a `define_insn' pattern.
RTL Template: The RTL template defines what insns match a pattern.
Output Template: The output template says how to make assembler code from such an insn.
Output Statement: For more generality, write C code to output the assembler code.
Constraints: When not all operands are general operands.
Standard Names: Names mark patterns to use for code generation.
Pattern Ordering: When the order of patterns makes a difference.
Dependent Patterns: Having one pattern may make you need another.
Jump Patterns: Special considerations for patterns for jump insns.
Insn Canonicalizations: Canonicalization of Instructions
Peephole Definitions: Defining machine-specific peephole optimizations.
Expander Definitions: Generating a sequence of several RTL insns for a standard operation.
Insn Splitting: Splitting Instructions into Multiple Instructions
Insn Attributes: Specifying the value of attributes for generated insns.

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