gcc.info: Allocation Order
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Order of Allocation of Registers
Registers are allocated in order.
`REG_ALLOC_ORDER'
If defined, an initializer for a vector of integers, containing the
numbers of hard registers in the order in which GNU CC should
prefer to use them (from most preferred to least).
If this macro is not defined, registers are used lowest numbered
first (all else being equal).
One use of this macro is on machines where the highest numbered
registers must always be saved and the save-multiple-registers
instruction supports only sequences of consecutive registers. On
such machines, define `REG_ALLOC_ORDER' to be an initializer that
lists the highest numbered allocable register first.
`ORDER_REGS_FOR_LOCAL_ALLOC'
A C statement (sans semicolon) to choose the order in which to
allocate hard registers for pseudo-registers local to a basic
block.
Store the desired register order in the array `reg_alloc_order'.
Element 0 should be the register to allocate first; element 1, the
next register; and so on.
The macro body should not assume anything about the contents of
`reg_alloc_order' before execution of the macro.
On most machines, it is not necessary to define this macro.
Created Wed Sep 1 16:42:24 2004 on bee with info_to_html version 0.9.6.