Bitcointalk · 4 hashes parallel on SSE2 CPUs for 0.3.6

中本聪,2010 年 8 月 14 日

SN-1910 已核对来源,附原文与上下文。

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MinGW GCC 4.5.0: Crypto++ 不能用,X86_SHA256_HashBlocks() 一直不返回 我只有用 test.cpp 时才让 4 路并行跑起来,被 BitcoinMiner 调用时就不行

MinGW GCC 4.4.1: Crypto++ 能用 4 路并行 SIGSEGV

GCC 显然没有对齐 __m128i。

即使我们自己把 __m128i 变量对齐了,编译器也可能在后台用 __m128i 当临时变量。

把我们的 __m128i 变量对齐、并把这几处 inline 改成 define 之后,我让它在 4.4.1 上用 -O0 跑通了:

#define Ch(b, c, d)  ((b & c) ^ (~b & d))
#define Maj(b, c, d)  ((b & c) ^ (b & d) ^ (c & d))
#define ROTR(x, n) (_mm_srli_epi32(x, n) | _mm_slli_epi32(x, 32 - n))
#define SHR(x, n)  _mm_srli_epi32(x, n)

但那是在 -O0 下。

ORIGINAL · 英文原文
MinGW GCC 4.5.0:
Crypto++ doesn't work, X86_SHA256_HashBlocks() never returns
I only got 4-way working with test.cpp but not when called by BitcoinMiner

MinGW GCC 4.4.1:
Crypto++ works
4-way SIGSEGV

GCC is definitely not aligning __m128i.

Even if we align our own __m128i variables, the compiler may decide to use a __m128i behind the scenes as a temporary variable.

By making our __m128i variables aligned and changing these inlines to defines, I was able to get it to work on 4.4.1 with -O0 only:
#define Ch(b, c, d)  ((b & c) ^ (~b & d))
#define Maj(b, c, d)  ((b & c) ^ (b & d) ^ (c & d))
#define ROTR(x, n) (_mm_srli_epi32(x, n) | _mm_slli_epi32(x, 32 - n))
#define SHR(x, n)  _mm_srli_epi32(x, n)

But that's with -O0.

来源
Bitcointalk 原始链接 ↗ 记录编号 SN-1910