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* doc/extend.texi (pcs): Document new attribute for ARM.

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Richard Earnshaw 2009-08-06 16:47:57 +00:00 committed by Richard Earnshaw
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@ -1,3 +1,7 @@
2009-08-06 Richard Earnshaw <rearnsha@arm.com>
* doc/extend.texi (pcs): Document new attribute for ARM.
2009-08-06 Richard Earnshaw <rearnsha@arm.com>
* arm.c (pcs_attribute_args): Comment out unsupported attribute

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gcc/doc/extend.texi
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@ -2830,6 +2830,28 @@ compiled with more aggressive optimization options that produce faster
and larger code, while other functions can be called with less
aggressive options.
@item pcs
@cindex @code{pcs} function attribute
The @code{pcs} attribute can be used to control the calling convention
used for a function on ARM. The attribute takes an argument that specifies
the calling convention to use.
When compiling using the AAPCS ABI (or a variant of that) then valid
values for the argument are @code{"aapcs"} and @code{"aapcs-vfp"}. In
order to use a variant other than @code{"aapcs"} then the compiler must
be permitted to use the appropriate co-processor registers (i.e., the
VFP registers must be available in order to use @code{"aapcs-vfp"}).
For example,
@smallexample
/* Argument passed in r0, and result returned in r0+r1. */
double f2d (float) __attribute__((pcs("aapcs")));
@end smallexample
Variadic functions always use the @code{"aapcs"} calling convention and
the compiler will reject attempts to specify an alternative.
@item pure
@cindex @code{pure} function attribute
Many functions have no effects except the return value and their