gcc.info: Constant Attributes
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Constant Attributes
A special form of `define_attr', where the expression for the
default value is a `const' expression, indicates an attribute that is
constant for a given run of the compiler. Constant attributes may be
used to specify which variety of processor is used. For example,
(define_attr "cpu" "m88100,m88110,m88000"
(const
(cond [(symbol_ref "TARGET_88100") (const_string "m88100")
(symbol_ref "TARGET_88110") (const_string "m88110")]
(const_string "m88000"))))
(define_attr "memory" "fast,slow"
(const
(if_then_else (symbol_ref "TARGET_FAST_MEM")
(const_string "fast")
(const_string "slow"))))
The routine generated for constant attributes has no parameters as it
does not depend on any particular insn. RTL expressions used to define
the value of a constant attribute may use the `symbol_ref' form, but
may not use either the `match_operand' form or `eq_attr' forms
involving insn attributes.
Created Wed Sep 1 16:42:24 2004 on bee with info_to_html version 0.9.6.