GCC internals - Instruction Patterns

GCC internals - Instruction Patterns

[htio2]

I am new to gcc compiler backend. I am currently studying how to the .md file
to have a understanding.

The thing that I don't understand is:

I understand the standard pattern like movsi and etc, but I can see some
pattern like movsi_internal, movsi_internal_v850e and etc, my question is
where in the spec can I find them ? and where are they define ?




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Re: GCC internals - Instruction Patterns

[Jeff Law]

On 10/05/2015 07:56 PM, htio2 wrote:
> I am new to gcc compiler backend. I am currently studying how to the .md file
> to have a understanding.
>
> The thing that I don't understand is:
>
> I understand the standard pattern like movsi and etc, but I can see some
> pattern like movsi_internal, movsi_internal_v850e and etc, my question is
> where in the spec can I find them ? and where are they define ?
Pattern names not mentioned in the internals manual are there primarily 
to make dumps easier to read.  In fact, if the name starts with a "*", 
then its sole purpose is to make debugging dumps easier to read. 
Neither the generic parts of the compiler, nor the target specific parts 
of the compiler can directly refer to those patterns by name.

Jeff

Re: GCC internals - Instruction Patterns

[htio2]

Ok, so you mean this non standard patterns is not use by compiler ?



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Re: GCC internals - Instruction Patterns

[Jeff Law]

On 10/05/2015 10:15 PM, htio2 wrote:
> Ok, so you mean this non standard patterns is not use by compiler ?
If they start with a "*" the patterns can not be referenced by the 
compiler directly, but if code which matches the structure of those 
patterns is created, then those patterns will be used.  Examples would 
be all the *movXX_internal patterns in the v850 machine description.

A non-standard name which does not start with a "*" can be referenced by 
the target to generate code.  Since you seem to be looking at the v850 
backend, an example would be the "save_interrupt" pattern which the v850 
backend can reference via gen_save_interrupt.

All this is explained in detail in the GCC internals manual.  I 
recommend you read it carefully.

jeff

Re: GCC internals - Instruction Patterns

[htio2]

ok, many thanks



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