Add SSE4 optimized SHA256

The SHA256 hashing optimizations for architectures supporting SSE4, which should lead to ~50% speedups in SHA256 on supported hardware (~5% faster synchronization and block validation).

- bitcoin/bitcoin@16240f4

Use --enable-experimental-asm in configure to enable SSE4.

configure.ac

@@ -167,6 +167,16 @@ AC_ARG_ENABLE([glibc-back-compat],
   [use_glibc_compat=$enableval],
   [use_glibc_compat=no])
 
+AC_ARG_ENABLE([experimental-asm],
+  [AS_HELP_STRING([--enable-experimental-asm],
+  [Enable experimental assembly routines (default is no)])],
+  [experimental_asm=$enableval],
+  [experimental_asm=no])
+
+if test "x$experimental_asm" = xyes; then
+  AC_DEFINE(EXPERIMENTAL_ASM, 1, [Define this symbol to build in experimental assembly routines])
+fi
+
 AC_ARG_ENABLE([zmq],
   [AS_HELP_STRING([--disable-zmq],
   [disable ZMQ notifications])],
@@ -1030,6 +1040,7 @@ AM_CONDITIONAL([USE_COMPARISON_TOOL],[test x$use_comparison_tool != xno])
 AM_CONDITIONAL([USE_COMPARISON_TOOL_REORG_TESTS],[test x$use_comparison_tool_reorg_test != xno])
 AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
 AM_CONDITIONAL([HARDEN],[test x$use_hardening = xyes])
+AM_CONDITIONAL([EXPERIMENTAL_ASM],[test x$experimental_asm = xyes])
 
 AC_DEFINE(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR, [Major version])
 AC_DEFINE(CLIENT_VERSION_MINOR, _CLIENT_VERSION_MINOR, [Minor version])

src/Makefile.am

@@ -409,6 +409,10 @@ crypto_libbitcoin_crypto_a_SOURCES = \
   crypto/verus_hash.h \
   crypto/verus_hash.cpp
 
+if EXPERIMENTAL_ASM
+crypto_libbitcoin_crypto_a_SOURCES += crypto/sha256_sse4.cpp
+endif
+
 if ENABLE_MINING
 EQUIHASH_TROMP_SOURCES = \
 	pow/tromp/equi_miner.h \

src/crypto/sha256.cpp

@@ -3,12 +3,22 @@
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include "crypto/sha256.h"
-
 #include "crypto/common.h"
 
+#include <assert.h>
 #include <string.h>
 #include <stdexcept>
 
+#if defined(__x86_64__) || defined(__amd64__)
+#if defined(EXPERIMENTAL_ASM)
+#include <cpuid.h>
+namespace sha256_sse4
+{
+void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks);
+}
+#endif
+#endif
+
 // Internal implementation code.
 namespace
 {
@@ -44,9 +54,10 @@ void inline Initialize(uint32_t* s)
     s[7] = 0x5be0cd19ul;
 }
 
-/** Perform one SHA-256 transformation, processing a 64-byte chunk. */
-void Transform(uint32_t* s, const unsigned char* chunk)
+/** Perform a number of SHA-256 transformations, processing 64-byte chunks. */
+void Transform(uint32_t* s, const unsigned char* chunk, size_t blocks)
 {
+    while (blocks--) {
     uint32_t a = s[0], b = s[1], c = s[2], d = s[3], e = s[4], f = s[5], g = s[6], h = s[7];
     uint32_t w0, w1, w2, w3, w4, w5, w6, w7, w8, w9, w10, w11, w12, w13, w14, w15;
 
@@ -126,11 +137,59 @@ void Transform(uint32_t* s, const unsigned char* chunk)
     s[5] += f;
     s[6] += g;
     s[7] += h;
+        chunk += 64;
+    }
 }
 
 } // namespace sha256
+
+typedef void (*TransformType)(uint32_t*, const unsigned char*, size_t);
+
+bool SelfTest(TransformType tr) {
+    static const unsigned char in1[65] = {0, 0x80};
+    static const unsigned char in2[129] = {
+        0,
+        32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 
+        32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 
+        0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0
+    };
+    static const uint32_t init[8] = {0x6a09e667ul, 0xbb67ae85ul, 0x3c6ef372ul, 0xa54ff53aul, 0x510e527ful, 0x9b05688cul, 0x1f83d9abul, 0x5be0cd19ul};
+    static const uint32_t out1[8] = {0xe3b0c442ul, 0x98fc1c14ul, 0x9afbf4c8ul, 0x996fb924ul, 0x27ae41e4ul, 0x649b934cul, 0xa495991bul, 0x7852b855ul};
+    static const uint32_t out2[8] = {0xce4153b0ul, 0x147c2a86ul, 0x3ed4298eul, 0xe0676bc8ul, 0x79fc77a1ul, 0x2abe1f49ul, 0xb2b055dful, 0x1069523eul};
+    uint32_t buf[8];
+    memcpy(buf, init, sizeof(buf));
+    // Process nothing, and check we remain in the initial state.
+    tr(buf, nullptr, 0);
+    if (memcmp(buf, init, sizeof(buf))) return false;
+    // Process the padded empty string (unaligned)
+    tr(buf, in1 + 1, 1);
+    if (memcmp(buf, out1, sizeof(buf))) return false;
+    // Process 64 spaces (unaligned)
+    memcpy(buf, init, sizeof(buf));
+    tr(buf, in2 + 1, 2);
+    if (memcmp(buf, out2, sizeof(buf))) return false;
+    return true;
+}
+
+TransformType Transform = sha256::Transform;
+
 } // namespace
 
+std::string SHA256AutoDetect()
+{
+#if defined(EXPERIMENTAL_ASM) && (defined(__x86_64__) || defined(__amd64__))
+    uint32_t eax, ebx, ecx, edx;
+    if (__get_cpuid(1, &eax, &ebx, &ecx, &edx) && (ecx >> 19) & 1) {
+        Transform = sha256_sse4::Transform;
+        assert(SelfTest(Transform));
+        return "sse4";
+    }
+#endif
+
+    assert(SelfTest(Transform));
+    return "standard";
+}
 
 ////// SHA-256
 
@@ -148,14 +207,14 @@ CSHA256& CSHA256::Write(const unsigned char* data, size_t len)
         memcpy(buf + bufsize, data, 64 - bufsize);
         bytes += 64 - bufsize;
         data += 64 - bufsize;
-        sha256::Transform(s, buf);
+        Transform(s, buf, 1);
         bufsize = 0;
     }
-    while (end >= data + 64) {
-        // Process full chunks directly from the source.
-        sha256::Transform(s, data);
-        bytes += 64;
-        data += 64;
+    if (end - data >= 64) {
+        size_t blocks = (end - data) / 64;
+        Transform(s, data, blocks);
+        data += 64 * blocks;
+        bytes += 64 * blocks;
     }
     if (end > data) {
         // Fill the buffer with what remains.

src/crypto/sha256.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2014 The Bitcoin Core developers
+// Copyright (c) 2014-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -7,26 +7,31 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string>
 
 /** A hasher class for SHA-256. */
 class CSHA256
 {
 public:
     static const size_t OUTPUT_SIZE = 32;
-
+private:
+    uint32_t s[8];
+    unsigned char buf[64];
+    size_t bytes;
+    void FinalizeNoPadding(unsigned char hash[OUTPUT_SIZE], bool enforce_compression);
+public:
     CSHA256();
     CSHA256& Write(const unsigned char* data, size_t len);
     void Finalize(unsigned char hash[OUTPUT_SIZE]);
     void FinalizeNoPadding(unsigned char hash[OUTPUT_SIZE]) {
     	FinalizeNoPadding(hash, true);
     };
     CSHA256& Reset();
-
-private:
-    uint32_t s[8];
-    unsigned char buf[64];
-    size_t bytes;
-    void FinalizeNoPadding(unsigned char hash[OUTPUT_SIZE], bool enforce_compression);
 };
 
+/** Autodetect the best available SHA256 implementation.
+ *  Returns the name of the implementation.
+ */
+std::string SHA256AutoDetect();
+
 #endif // BITCOIN_CRYPTO_SHA256_H