Re: reload problems....

[Alan Lehotsky <apl at alum dot mit dot edu>]

At 2:30 AM +1200 7/21/01, thomas joseph wrote:

>Hi All,
> I am working for a new gcc port. I am towards
>finishing the port. I am compiling newlib.
>It has few reload problems. I am just showing you the
>kind of problems that I am facing.....
>
>   On my machine I have two index registers.Out of
>them
>one is  frame pointer. and I can use the other for
>reloading and similar purposes.


	I've done a couple of ports with these kinds of limitations.  It is really pushing the
	limits of gcc and reload.

	First, there are some obvious things you should check, like to make sure that

		1/ SMALL_REGISTER_CLASSES is defined
		2/ CLASS_LIKELY_SPILLED_P is defined for the class containing your index register.

	But, I bet that you've already done that, or you'd have a LOT more failures.

	The next thing is to look at defining the LEGITIMIZE_RELOAD_ADDRESS macro and using it
	to force the kind of reloads you need.

	To actually look at what reload is "thinking", you call run the compiler under gdb and after it
	aborts, you call do

		call debug_reload()

	and it will print out a nicely formatted dump of the current reloads for the instruction.

	You may find it necessary to alter your .MD file to prevent creating instructions with
	too many reloads.

	For example, on one of my ports, we had to change the .md file, so that there were NEVER two
	memory operands in any INSN, despite the fact that we we had a two-address machine.

	I wonder though if the "fixed or forbidden register" message indicates that you've marked the IX
	register as "fixed".  In that case, I believe that the compiler won't allocate it and THAT's why
	you're crashing.......

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