* tm.texi (SMALL_REGISTER_CLASSES): Make description match reality.
From-SVN: r24092
This commit is contained in:
parent
4dab1f3e9f
commit
faa9eb1977
|
@ -1,5 +1,7 @@
|
||||||
Fri Dec 4 20:15:57 1998 Bernd Schmidt <crux@pool.informatik.rwth-aachen.de>
|
Fri Dec 4 20:15:57 1998 Bernd Schmidt <crux@pool.informatik.rwth-aachen.de>
|
||||||
|
|
||||||
|
* tm.texi (SMALL_REGISTER_CLASSES): Make description match reality.
|
||||||
|
|
||||||
* final.c (cleanup_subreg_operands): Delete some unused code.
|
* final.c (cleanup_subreg_operands): Delete some unused code.
|
||||||
|
|
||||||
* recog.h (MAX_RECOG_ALTERNATIVES): New macro.
|
* recog.h (MAX_RECOG_ALTERNATIVES): New macro.
|
||||||
|
|
14
gcc/tm.texi
14
gcc/tm.texi
|
@ -2022,17 +2022,15 @@ is @code{BITS_PER_WORD} bits wide is correct for your machine.
|
||||||
|
|
||||||
@findex SMALL_REGISTER_CLASSES
|
@findex SMALL_REGISTER_CLASSES
|
||||||
@item SMALL_REGISTER_CLASSES
|
@item SMALL_REGISTER_CLASSES
|
||||||
Normally the compiler avoids choosing registers that have been
|
On some machines, it is risky to let hard registers live across arbitrary
|
||||||
explicitly mentioned in the rtl as spill registers (these registers are
|
insns. Typically, these machines have instructions that require values
|
||||||
normally those used to pass parameters and return values). However,
|
to be in specific registers (like an accumulator), and reload will fail
|
||||||
some machines have so few registers of certain classes that there
|
if the required hard register is used for another purpose across such an
|
||||||
would not be enough registers to use as spill registers if this were
|
insn.
|
||||||
done.
|
|
||||||
|
|
||||||
Define @code{SMALL_REGISTER_CLASSES} to be an expression with a non-zero
|
Define @code{SMALL_REGISTER_CLASSES} to be an expression with a non-zero
|
||||||
value on these machines. When this macro has a non-zero value, the
|
value on these machines. When this macro has a non-zero value, the
|
||||||
compiler allows registers explicitly used in the rtl to be used as spill
|
compiler will try to minimize the lifetime of hard registers.
|
||||||
registers but avoids extending the lifetime of these registers.
|
|
||||||
|
|
||||||
It is always safe to define this macro with a non-zero value, but if you
|
It is always safe to define this macro with a non-zero value, but if you
|
||||||
unnecessarily define it, you will reduce the amount of optimizations
|
unnecessarily define it, you will reduce the amount of optimizations
|
||||||
|
|
Loading…
Reference in New Issue