* doc/tm.texi (HARD_REGNO_RENAME_OK): Document.

From-SVN: r78998

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 95ac3d75af7fee507373309acdcbc57b715c2ba2..78fd63c9beca52006cc3c71ac2fca56401dbbfbb 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,7 @@
+2004-03-05  Kazu Hirata  <kazu@cs.umass.edu>
+
+       * doc/tm.texi (HARD_REGNO_RENAME_OK): Document.
+
 2004-03-05  Jason Merrill  <jason@redhat.com>
 
        * tree.h (TYPE_HASH): Use TYPE_UID.

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 3ca5acae3ff0d77fdd0b92856a9c2dce6a3fe0c9..1bf6defe6ed7f455e4552b0b89ec361e351aa72c 100644 (file)
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -2072,6 +2072,17 @@ floating registers are not in class @code{GENERAL_REGS}, they will not
 be used unless some pattern's constraint asks for one.
 @end defmac
 
+@defmac HARD_REGNO_RENAME_OK (@var{from}, @var{to})
+A C expression that is nonzero if it is OK to rename a hard register
+@var{from} to another hard register @var{to}.
+
+One common use of this macro is to prevent renaming of a register to
+another register that is not saved by a prologue in an interrupt
+handler.
+
+The default is always nonzero.
+@end defmac
+
 @defmac MODES_TIEABLE_P (@var{mode1}, @var{mode2})
 A C expression that is nonzero if a value of mode
 @var{mode1} is accessible in mode @var{mode2} without copying.