[llvm-commits] Speeding up instruction selection

[Dan Gohman]

On Apr 23, 2008, at 10:27 AM, Roman Levenstein wrote:
>
> Just to make it clear:
> This patch is applied currently to the output of Tablegen.
> But the proper patch will need to change the Tablegen to generate
> correct *.inc files.
> Thinking about it, I have a question:
> Right now, the beginning of the generrated instruction selector files
> is always the same, independent of the *.td file and target
> architecture.
> But it is generated by tablegen still and therefore cannot be
> substituted easily, without changing the tablegen.
> Question: May be it is better to define this common part in an include
> file, e.g. ISelHeader.h, and then tablegen would generate only the
> #include <llvm/CodeGen/ISelHeader.h> line. What do you think?

Another option is to move common code into the
SelectionDAGISel parent class, which is a common base class
for each of the targets' DAGToDAGISel classes.

Dan