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Re: rtx structure


Bharati Bhole writes:
 > On 11/2/06, Andrew Haley <aph@redhat.com> wrote:
 > > Bharati Bhole writes:
 > >  > On 11/2/06, Daniel Berlin <dberlin@dberlin.org> wrote:
 > >  > > > I want to know what part of rtx each field in this structure stores.
 > >  > > > While tracing through gdb i tried to print the rtx, and i was not able
 > >  > > > to understand that. Could u please explain me it with a sample RTX
 > >  > > > that what value these fields have.
 > >  > > >
 > >  > >
 > >  > > The macros used to access the rtl fields in rtl.h explain what part of
 > >  > > each field they access and what they treat that object as.
 > >  > >
 > >  > > The definitions of rtl in rtl.def define what each portion of a piece
 > >  > > of valid RTL is structured as.
 > >  > > > Bharati.
 > >  > > >
 > >  > >
 > >  >
 > >  > I have gone through the structure but i still dont get it.
 > >  > Could anybody please tell me, if the following insn is  a sample insn,
 > >  > how will the rtx structure look like -
 > >  >         (define_insn "subsi3_carry_zext"
 > >  >         [(set (match_operand:DI 0 "register_operand" "=rm,r")
 > >  >                  (zero_extend:DI
 > >  >                (minus:SI (match_operand:SI 1 "register_operand" "0,0")
 > >  >                           (plus:SI (match_operand:SI 3
 > >  > "ix86_carry_flag_operator" "")
 > >  >                               (match_operand:SI 2 "general_operand" "ri,rm")))))
 > >  >           (clobber (reg:CC FLAGS_REG))]
 > >  >        "TARGET_64BIT && ix86_binary_operator_ok (MINUS, SImode, operands)"
 > >  >        "sbb{l}\t{%2, %k0|%k0, %2}"
 > >  >       [(set_attr "type" "alu")
 > >  >       (set_attr "pent_pair" "pu")
 > >  >       (set_attr "mode" "SI")])
 > >
 > > But this isn't a simple insn, it's a machine description pattern.
 > > These are described in Section 13, Machine Descriptions.

 > Yes, this is a machine description pattern. In the genrecog.c file the
 > .md file is read and from each insn the RTL template is filled in the
 > RTX structure. So i want to know that how this insn ie the RTL teplate
 > from this insn will be filled in the RTX structure. I mean what part
 > of the template, each field of RTX structure will store? Could anybody
 > please tell me that?

Possibly, but it would be better for you to find out for yourself.
Have you tried putting a breakpoint on make_insn_raw ?

Andrew.


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