explaination of some gcc functions

[kernel coder]

I'm having trouble in understanding the term sequnce in an insn
chain.get_insns() actually returns the current instruction.What does
the term "sequence" mean,as the name suggests it must be a sequence of
instructions ,but in an instruction chain,a single element will be an
instruction ,then what is meant by sequence.

When push_topmost_sequence is called ,it should push a sequence of
instructions ,but an element of insn chain is a single
instruction,then which sequence will be pushed.

Suppose following is a sequnce of instructions.

1)    entry_insns = get_insns ();
2)     push_topmost_sequence ();
3)      emit_insn_after (entry_insns, get_insns ());
4)      pop_topmost_sequence ();

In 1) current insn is saved in entry_insns. what is happening in In
2).Is sequence differnet from insn in an insn chain ,any example will
be helpful.

In 3) instruction  the entry_insns is being put after the instruction
obtained through get_insns() .But does get_insns() also increaments
the current instruction pointer.If not then shouldn't the same
instruction be emitted in 3).

Now again which sequnce is being  poped out in 4).


On 7/1/06, Eric Christopher <echristo@apple.com> wrote:
> kernel coder wrote:
> > hi,
> >     I'm trying to understand the backend code of gcc for MIPS
> > architecture.I'm having some trouble while understanding following
> > functions.
>
> I think most of these are obvious, what problems in specific are you
> having with them?
>
> -eric
>