build: Rename --enable-experimental-asm to --enable-asm and enable by default

Now that 0.15 is branched off, enable assembler SHA256 optimizations by default.

configure.ac

@@ -177,14 +177,14 @@ 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])
+AC_ARG_ENABLE([asm],
+  [AS_HELP_STRING([--enable-asm],
+  [Enable assembly routines (default is yes)])],
+  [use_asm=$enableval],
+  [use_asm=yes])
+
+if test "x$use_asm" = xyes; then
+  AC_DEFINE(USE_ASM, 1, [Define this symbol to build in assembly routines])
 fi
 
 AC_ARG_WITH([system-univalue],
@@ -1179,7 +1179,7 @@ AM_CONDITIONAL([USE_LCOV],[test x$use_lcov = xyes])
 AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
 AM_CONDITIONAL([HARDEN],[test x$use_hardening = xyes])
 AM_CONDITIONAL([ENABLE_HWCRC32],[test x$enable_hwcrc32 = xyes])
-AM_CONDITIONAL([EXPERIMENTAL_ASM],[test x$experimental_asm = xyes])
+AM_CONDITIONAL([USE_ASM],[test x$use_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

@@ -271,7 +271,7 @@ crypto_libbitcoin_crypto_a_SOURCES = \
   crypto/sha512.cpp \
   crypto/sha512.h
 
-if EXPERIMENTAL_ASM
+if USE_ASM
 crypto_libbitcoin_crypto_a_SOURCES += crypto/sha256_sse4.cpp
 endif
 

src/crypto/sha256.cpp

@@ -10,7 +10,7 @@
 #include <atomic>
 
 #if defined(__x86_64__) || defined(__amd64__)
-#if defined(EXPERIMENTAL_ASM)
+#if defined(USE_ASM)
 #include <cpuid.h>
 namespace sha256_sse4
 {
@@ -178,7 +178,7 @@ TransformType Transform = sha256::Transform;
 
 std::string SHA256AutoDetect()
 {
-#if defined(EXPERIMENTAL_ASM) && (defined(__x86_64__) || defined(__amd64__))
+#if defined(USE_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;