Patchwork Doc patch committed: The '+' constraint does not require a register

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Submitter Ian Taylor
Date Oct. 24, 2012, 4:47 a.m.
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Permalink /patch/193680/
State New
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Ian Taylor - Oct. 24, 2012, 4:47 a.m.
Back in May 2004 Richard Henderson ensured that using a '+' constraint
in an extended asm statement would work with an 'm' constraint.

Unfortunately he did not update the documentation.  I verified that
Richard's code is still in the compiler, and updated the documentation
as follows.

Bootstrapped on x86_64-unknown-linux-gnu.  Committed to mainline.


2012-10-23  Ian Lance Taylor  <>

	* doc/extend.texi (Extended Asm): The '+' constraint does not
	require a register.


Index: doc/extend.texi
--- doc/extend.texi	(revision 192525)
+++ doc/extend.texi	(working copy)
@@ -5864,10 +5864,7 @@  The ordinary output operands must be wri
 the values in these operands before the instruction are dead and need
 not be generated.  Extended asm supports input-output or read-write
 operands.  Use the constraint character @samp{+} to indicate such an
-operand and list it with the output operands.  You should only use
-read-write operands when the constraints for the operand (or the
-operand in which only some of the bits are to be changed) allow a
+operand and list it with the output operands.
 You may, as an alternative, logically split its function into two
 separate operands, one input operand and one write-only output