Re: [Tinycc-devel] Optimizing code for expressions

[Jim Peters]

Laurent DESNOGUES wrote:
>    Nothing prevents you from using a pseudo RISC with an
> infinite number of registers.  This is indeed done by several
> assemblers:  ti c6x assembler, and ps2 VU assembler vcl.
> Both have the register allocator in the assembler.

Interesting.

>    Regarding the stack-based IL, I used a compiler kit (ACK,
> Amsterdam Compiler Kit) with a back-end generator.  The IL,
> named em, was a stack-based IL.  The main thing I remember
> from this time was the high complexity of the em optimizer...

Okay, I think I can see why a pure stack-based system could be harder
to optimise -- especially as accessing local variables means
loading/storing values from lower down in the stack, i.e. effectively
needing to make temporary copies with extra operations.

Perhaps RISC + infinite registers and pure stack-based systems should
be regarded as two extremes, with the end-target somewhere between
them, with a limited register file and everything else on the stack.

Jim

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