Confused about rtl generation

[Jim Wilson]

On Fri, 2003-06-27 at 01:50, Marty Hauff wrote:
> Given what you are saying about the transient nature of the insns it would be ideal if the standard pattern used to create the insn list in the first place could somehow be kept with the insn.

We don't keep the info because we don't need it.  You can't reuse
INSN_CODE for this purpose.

> I was wondering if you could comment on the amount of work that might be involved in adding a new field to the insn definition.

Adding a new field is relatively easy.  Geting the info you want to put
in it will be hard.

> If I call recog() just after the initial RTL generation pass (around when .00.rtl is written and prior to optimizations etc.) this routine should fill in the insn ids with the same code as the insn that was used to create the rtl originally?

No. Because some patterns are only used to generate RTL, e.g.
define_expands.  They are never used for pattern matching, so there is
no way to get back to them.

See the info on define_expand, define_insn, and named patterns in the
manual, and look at how they are used in any port.

Jim