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Date: Tue, 22 May 2012 13:06:42 -0300
From: Claudio André <>
Subject: Re: Nvidia compiler bug

Em 21-05-2012 21:04, magnum escreveu:
> Interesting. What went wrong and how did you mitigate it?
I had something like this
void kernel_crypt(parameters, ...
                   __local    crypt_sha512_salt     * salt_data,
                   __local    working_memory      * fast_tmp_memory) {

Even if it was ok on runtime, it was hurting my possibilities. So i 
changed to:
void kernel_crypt(parameters, ...){
     __local crypt_sha512_salt     * salt_data[1];
     __local working_memory      * tmp_memory[SIZE];

      more code;

The point is that i was misunderstanding what was generated as object 
code, so i understood wrong the results i got. Maybe, i shouldn't call 
this an Nvidia bug (i had troubles using __local pointers and i did 1+1 
and, there is a bug somewhere). I solved my misunderstandings and:
1. shake the code.
2. make correct assumptions and conclusions.

So, another 2 important things happen:
1. i realized LWS (or LWS + KPC) is much more important than i was thinking.
2. i found a better solution for the real bug on an unroll (the most 
important) i have.
> Btw I'm curious why your attempt at avoiding byte addressable store
> failed. When/where was it misaligned?
After this, i was afraid i'm facing other crazy thing:
- TESTE *not* defined: CPU: Ok,  GPU: ok.
- if TESTE is defined: CPU: worse performance   GPU: FAILED (get_hash[0](0))

void insert_to_buffer(sha512_ctx    * ctx,
                       const uint8_t * string,
                       const uint32_t len) { // len range: 1 to 64
#ifdef TESTE
     uint32_t *d = (uint32_t *) (ctx->buffer->mem_08 + ctx->buflen);
     #define PUTCHAR_MAGNUM(buf, index, val) (buf)[(index)>>2] = 
((buf)[(index)>>2] & ~(0xffU << (((index) & 3) << 3))) + ((val) << 
(((index) & 3) << 3))
     uint8_t *d = ctx->buffer->mem_08 + ctx->buflen;
     #define PUTCHAR_MAGNUM(buf, index, val) (buf)[index] = (val)
     for (uint32_t i = 0; i < len; i++)
         PUTCHAR_MAGNUM(d, i, GETCHAR(string, i));

     ctx->buflen += len;

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