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Elaborate docs for HOST_WIDE_INT


The patch below documents how narrow constants are represented in a const_rtx.
Ok?

Paul

2005-01-20  Paul Brook  <paul@codesourcery.com>

 * doc/rtl.texi: Document value extension requirements for CONST_INT.

Index: rtl.texi
===================================================================
RCS file: /var/cvsroot/gcc-cvs/gcc/gcc/doc/rtl.texi,v
retrieving revision 1.79
diff -u -p -r1.79 rtl.texi
--- rtl.texi 5 Jan 2005 23:19:23 -0000 1.79
+++ rtl.texi 20 Jan 2005 21:38:36 -0000
@@ -1286,6 +1286,9 @@ This type of expression represents the i
 is customarily accessed with the macro @code{INTVAL} as in
 @code{INTVAL (@var{exp})}, which is equivalent to @code{XWINT (@var{exp}, 0)}.
 
+Constants generated for modes with less bits than @code{HOST_WIDE_INT}
+must be sign extended to full width (e.g., with @code{gen_int_mode}).
+
 @findex const0_rtx
 @findex const1_rtx
 @findex const2_rtx


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