Re: [Iverilog-devel] VVP Performance boots

[Stephen W. <st...@ic...>]

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Cary R. wrote:
| --- 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 ;-)


Tell me what the attached program does for you on your machine.
When I compile it for 64bit (cc foo.c) and 32bits (cc -m32 foo.c)
I get the correct answer. And of course, on PPC32 I get the correct
results. I expect (1<<32) to be 0 on a 32bit machine.

Still, I'm fixing it here. Try pulling from git.

- --
Steve Williams                "The woods are lovely, dark and deep.
steve at icarus.com           But I have promises to keep,
http://www.icarus.com         and lines to code before I sleep,
http://www.picturel.com       And lines to code before I sleep."
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