On Mon, Apr 14, 2008 at 11:07 PM, Ian Lance Taylor <[EMAIL PROTECTED]> wrote: > > "Mohamed Shafi" <[EMAIL PROTECTED]> writes: > > > I have read in the internals that indirect_jump and jump pattern are > > necessary in any back-end for the compiler to be build and work > > successfully. For any back-end there will be some limitation as to how > > big the offset used in the jump instructions can be. If the offset is > > too big then the indirect_jump pattern has to utilized. Now my > > question is how will i be able to specify the limit of the offset so > > the gcc generates indirect_jump pattern instead of the jump pattern? I > > hope i am clear. > > From the perspective of insn names, it's not quite accurate to say > that jump turns into indirect_jump. It would be more correct to say > that when there is a limit to the offset for jump, it needs to use a > register. > > The way to handle this is to set the "length" attribute correctly for > each insn, and to change code generation based on the length. See, > e.g., the mips.md "jump" insn for an example. > Ok , looking at another reply from Jim (http://gcc.gnu.org/ml/gcc/2008-04/msg00311.html), where he suggests to use shorten_branhes in reorg and generate indirect branch, it looks like i will have to reserve a register. Am i right?
If that is the case it seems that there is no need for a indirect_jump pattern. So can you tell me when exactly are the indirect_jump patterns will be utilized by gcc? Regards, Shafi
