On Wed, May 28, 2014 at 03:54:58PM -0600, Jeff Law wrote:
> >Why not get rid of all the above 4 lines and just keep:
> >
> >> return CONSTANT_P (op);
> >
> >? CONST matches CONSTANT_P, and what is inside of CONST should be
> >fine, and (plus (symbol_ref) (const_int)) not surrounded by CONST
> >ir invalid.
> Haven't we recently had problems with being overly accepting of
> stuff inside CONST when using the CONST for address expressions.
> ISTM we should only accept what the processor supports here.
The only recent problem I remember was that we forgot to put CONST
around (plus (symbol_ref) (const_int)), but I see no problem not
accepting such invalid RTL.
The processor shouldn't care, for the instructions a CONST is just
any kind of immediate, what exactly it is matters solely to the
assembler/linker and dynamic linker
(if there are relocations for it, if the expression can be expressed in
the assembly, etc.). But that is common to all CONST operands, there is
nothing special particularly about sibcalls.
Jakub
