Re: [Iverilog-devel] VVP Performance boots

[Cary R. <cy...@ya...>]

--- On Tue, 4/22/08, Stephen Williams <st...@ic...> wrote:


> We need to look more carefully at the of_ADDI instruction.
> The
> most likely problem is the vector_to_array() call returning
> a
> wrong value.

A very good guess! It's actually in vvp_vector4_t::subarray() in vvp_net.cc. In this case we are getting 32 bits at address 32, so on a 32 bit machine we are word aligned. The problem is that the atmp and btmp masking is failing. before the masking we have the correct value after it we have zero. This is caused by the fact that you cannot shift a 32 bit value by 32 bits. The same thing could also happen with 64 bit values. The 100 was a red hearing since it broke the word alignment.

I will let you decide how you want to fix this. As I remember I fixed something like this in the exact same routine not too long ago. Of course that was before you rewrote it to work with the new layout ;-)

Cary


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