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[PATCH] Small fix to the docs
- From: Eric Botcazou <ebotcazou at libertysurf dot fr>
- To: gcc-patches at gcc dot gnu dot org
- Date: Sat, 13 Nov 2004 11:06:03 +0100
- Subject: [PATCH] Small fix to the docs
Hello,
I just spotted this in the docs, section SUBREG:
It is also not valid to access a single word of a multi-word value
in a hard register when less registers can hold the value than
would be expected from its size. For example, some 32-bit
machines have floating-point registers that can hold an entire
`DFmode' value. If register 10 were such a register `(subreg:SI
(reg:DF 10) 1)' would be invalid because there is no way to
convert that reference to a single machine register. The reload
pass prevents `subreg' expressions such as these from being formed.
I think the '1' dates back to when BYTENUM was counted in words and not bytes.
OK for all active branches?
2004-11-13 ?Eric Botcazou ?<ebotcazou@libertysurf.fr>
* doc/rtl.texi (SUBREG): Adjust BYTENUM value.
--
Eric Botcazou
Index: doc/rtl.texi
===================================================================
RCS file: /cvs/gcc/gcc/gcc/doc/rtl.texi,v
retrieving revision 1.75
diff -u -r1.75 rtl.texi
--- doc/rtl.texi 5 Nov 2004 01:36:57 -0000 1.75
+++ doc/rtl.texi 13 Nov 2004 09:59:01 -0000
@@ -1618,7 +1618,7 @@
hard register when less registers can hold the value than would be
expected from its size. For example, some 32-bit machines have
floating-point registers that can hold an entire @code{DFmode} value.
-If register 10 were such a register @code{(subreg:SI (reg:DF 10) 1)}
+If register 10 were such a register @code{(subreg:SI (reg:DF 10) 4)}
would be invalid because there is no way to convert that reference to
a single machine register. The reload pass prevents @code{subreg}
expressions such as these from being formed.