Patchwork doc: add pdp11 machine constraints

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Submitter Paul Koning
Date Nov. 4, 2010, 9:18 p.m.
Message ID <CC83B672-21BD-4BD9-9E33-BC389C37ACC1@dell.com>
Download mbox | patch
Permalink /patch/70169/
State New
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Comments

Paul Koning - Nov. 4, 2010, 9:18 p.m.
The machine constraints section was missing the pdp11 target specific constraints.  This patch adds them.

Tested with make info, make pdf.  Committed.

	paul

ChangeLog:

2010-11-04  Paul Koning  <ni1d@arrl.net>

	* doc/md.texi (Machine Constraints): Add PDP-11 constraints.
Joseph S. Myers - Nov. 5, 2010, 12:45 a.m.
On Thu, 4 Nov 2010, Paul Koning wrote:

> +Odd numbered general registers (R1, R3, R5).  These are used for 16
> +bit multiply operations.

"16-bit", with a hyphen.

> +@item M
> +The integer constant -1.

@minus{}1.

> +Integer constants -4 through -1 and 1 through 4; shifts by these

Likewise, @minus{}4 and @minus{1}.

Patch

Index: doc/md.texi
===================================================================
--- doc/md.texi	(revision 166333)
+++ doc/md.texi	(working copy)
@@ -2921,6 +2921,55 @@ 
 
 @end table
 
+@item PDP-11---@file{config/pdp11/constraints.md}
+@table @code
+@item a
+Floating point registers AC0 through AC3.  These can be loaded from/to
+memory with a single instruction.
+
+@item d
+Odd numbered general registers (R1, R3, R5).  These are used for 16
+bit multiply operations.
+
+@item f
+Any of the floating point registers (AC0 through AC5).
+
+@item G
+Floating point constant 0.
+
+@item I
+An integer constant that fits in 16 bits.
+
+@item J
+An integer constant whose low order 16 bits are zero.
+
+@item K
+An integer constant that does not meet the constraints for codes
+@samp{I} or @samp{J}.
+
+@item L
+The integer constant 1.
+
+@item M
+The integer constant -1.
+
+@item N
+The integer constant 0.
+
+@item O
+Integer constants -4 through -1 and 1 through 4; shifts by these
+amounts are handled as multiple single-bit shifts rather than a single
+variable-length shift.
+
+@item Q
+A memory reference which requires an additional word (address or
+offset) after the opcode.
+
+@item R
+A memory reference that is encoded within the opcode.
+
+@end table
+
 @item RX---@file{config/rx/constraints.md}
 @table @code
 @item Q