Re: A newbie question: Maping pseudos to declaration.

[Ian Lance Taylor <ian at airs dot com>]

N V Krishna <nvk@cs.ucla.edu> writes:

> I am trying to do some modifications to the register allocator and for the
> architecture I am dealing with, I want to handle different type of pseudos
> differently. All local scalars fall under one group, local struct/union
> variables under one group and all globals under one group. Given a pseudo,
> I want to know which group it is being used with.

It's hard to make sense of a strict distinction between local scalars
and local struct/union variables in gcc 4.  The SRA optimization means
that struct/union variables will sometimes be handled as a collection
of independent scalar values.  See tree-sra.c.

> For some pseudos reg_equiv_memory_loc is returning NULL. And those are the
> cases that are causing me to thing otherwise.

This will happen for a local variable which has not been spilled onto
the stack, and is thus always held in registers (this could be either
a scalar variable or a struct/union variable).  It will also happen
for pseudos which hold sufficiently simple constant values--see the
reg_equiv_constant array.

Ian