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Re: conditional based transfer pattern issue in md file
- From: Ian Lance Taylor <iant at google dot com>
- To: "Sivaprasad.pv" <sivaprasad dot pv at redpinesignals dot com>
- Cc: gcc <gcc-help at gcc dot gnu dot org>
- Date: 01 Feb 2008 07:40:31 -0800
- Subject: Re: conditional based transfer pattern issue in md file
- References: <47A2E218.8070009@redpinesignals.com>
"Sivaprasad.pv" <sivaprasad.pv@redpinesignals.com> writes:
> While updating the machine description file for our architecture ,we
> encountered the problem regarding conditional based transfer.
> In gcc internals specified that conditional based transfer can be
> supported using the standard pattern 'movModecc' as shown below.
> op0=(cc)? op2:op3
> But our architecture supports conditional transfer instruction as
> shown below:
> T<CC> op1, op2 It transfers the op1 to op2 if the <CC>
> is true otherwise it should behave like 'nop' .
> would u people tell me ,how to define the pattern in machine
> description file regarding the above specified issue.
Use a "0" constraint to force one of the operands to be in the same
location as operand 0. See the i386 movsicc_nocc insn for an example.
Ian