[PATCH v2 0/7] Optimize jump label implementation on ARM64

Will Deacon will.deacon at arm.com
Mon Oct 14 12:41:34 EDT 2013


On Mon, Oct 14, 2013 at 05:04:20PM +0100, Russell King - ARM Linux wrote:
> > On 10/14/2013 11:40 PM, Russell King - ARM Linux wrote:
> |  In the simplest case, a `%' followed by a digit N says to output
> | operand N at that point in the string.
> | 
> |  `%' followed by a letter and a digit says to output an operand in an
> | alternate fashion.  Four letters have standard, built-in meanings
> | described below.  The machine description macro `PRINT_OPERAND' can
> | define additional letters with nonstandard meanings.
> | 
> |  `%cDIGIT' can be used to substitute an operand that is a constant
> | value without the syntax that normally indicates an immediate operand.
> | ...
> |  `%lDIGIT' is used to substitute a `label_ref' into a jump instruction.
> 
> %lDIGIT is used (but not commented upon) in the gcc extended asm
> documentation where it talks about asm gotos, so there's probably a doc
> bug here too about whether these options should be described in the
> main doc as well.
> 
> Nevertheness, this section is documenting the _internals_ of gcc, and
> it seems perverse for a gcc backend to ignore something that is
> documented as being a standard part of gcc.

I'll make sure this gets fixed.

Will



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