Merge bitcoin-core/secp256k1#1446: field: Remove x86_64 asm

f07cead build: Don't call assembly an optimization (Tim Ruffing)
2f0762f field: Remove x86_64 asm (Tim Ruffing)

Pull request description:

ACKs for top commit:
  sipa:
    utACK f07cead
  theStack:
    ACK f07cead
  jonasnick:
    ACK f07cead

Tree-SHA512: df7f895ab8ab924c5f8f01c35d0cd2f65d5c947c5ab5325787d169c5b202834ab8aa5d85dedb25839fff3f518097fe8cf8e837d3c1918e5f039ddd6ddf4187da

CMakeLists.txt

@@ -107,7 +107,7 @@ if(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
 endif()
 mark_as_advanced(FORCE SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
 
-set(SECP256K1_ASM "AUTO" CACHE STRING "Assembly optimizations to use: \"AUTO\", \"OFF\", \"x86_64\" or \"arm32\" (experimental). [default=AUTO]")
+set(SECP256K1_ASM "AUTO" CACHE STRING "Assembly to use: \"AUTO\", \"OFF\", \"x86_64\" or \"arm32\" (experimental). [default=AUTO]")
 set_property(CACHE SECP256K1_ASM PROPERTY STRINGS "AUTO" "OFF" "x86_64" "arm32")
 check_string_option_value(SECP256K1_ASM)
 if(SECP256K1_ASM STREQUAL "arm32")
@@ -117,7 +117,7 @@ if(SECP256K1_ASM STREQUAL "arm32")
   if(HAVE_ARM32_ASM)
     add_compile_definitions(USE_EXTERNAL_ASM=1)
   else()
-    message(FATAL_ERROR "ARM32 assembly optimization requested but not available.")
+    message(FATAL_ERROR "ARM32 assembly requested but not available.")
   endif()
 elseif(SECP256K1_ASM)
   include(CheckX86_64Assembly)
@@ -128,14 +128,14 @@ elseif(SECP256K1_ASM)
   elseif(SECP256K1_ASM STREQUAL "AUTO")
     set(SECP256K1_ASM "OFF")
   else()
-    message(FATAL_ERROR "x86_64 assembly optimization requested but not available.")
+    message(FATAL_ERROR "x86_64 assembly requested but not available.")
   endif()
 endif()
 
 option(SECP256K1_EXPERIMENTAL "Allow experimental configuration options." OFF)
 if(NOT SECP256K1_EXPERIMENTAL)
   if(SECP256K1_ASM STREQUAL "arm32")
-    message(FATAL_ERROR "ARM32 assembly optimization is experimental. Use -DSECP256K1_EXPERIMENTAL=ON to allow.")
+    message(FATAL_ERROR "ARM32 assembly is experimental. Use -DSECP256K1_EXPERIMENTAL=ON to allow.")
   endif()
 endif()
 
@@ -280,7 +280,7 @@ message("Parameters:")
 message("  ecmult window size .................. ${SECP256K1_ECMULT_WINDOW_SIZE}")
 message("  ecmult gen precision bits ........... ${SECP256K1_ECMULT_GEN_PREC_BITS}")
 message("Optional features:")
-message("  assembly optimization ............... ${SECP256K1_ASM}")
+message("  assembly ............................ ${SECP256K1_ASM}")
 message("  external callbacks .................. ${SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS}")
 if(SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY)
   message("  wide multiplication (test-only) ..... ${SECP256K1_TEST_OVERRIDE_WIDE_MULTIPLY}")

Makefile.am

@@ -37,7 +37,6 @@ noinst_HEADERS += src/field_10x26_impl.h
 noinst_HEADERS += src/field_5x52.h
 noinst_HEADERS += src/field_5x52_impl.h
 noinst_HEADERS += src/field_5x52_int128_impl.h
-noinst_HEADERS += src/field_5x52_asm_impl.h
 noinst_HEADERS += src/modinv32.h
 noinst_HEADERS += src/modinv32_impl.h
 noinst_HEADERS += src/modinv64.h

README.md

@@ -33,7 +33,7 @@ Implementation details
   * Expose only higher level interfaces to minimize the API surface and improve application security. ("Be difficult to use insecurely.")
 * Field operations
   * Optimized implementation of arithmetic modulo the curve's field size (2^256 - 0x1000003D1).
-    * Using 5 52-bit limbs (including hand-optimized assembly for x86_64, by Diederik Huys).
+    * Using 5 52-bit limbs
     * Using 10 26-bit limbs (including hand-optimized assembly for 32-bit ARM, by Wladimir J. van der Laan).
       * This is an experimental feature that has not received enough scrutiny to satisfy the standard of quality of this library but is made available for testing and review by the community.
 * Scalar operations

configure.ac

@@ -201,7 +201,7 @@ AC_ARG_ENABLE(external_default_callbacks,
 AC_ARG_WITH([test-override-wide-multiply], [] ,[set_widemul=$withval], [set_widemul=auto])
 
 AC_ARG_WITH([asm], [AS_HELP_STRING([--with-asm=x86_64|arm32|no|auto],
-[assembly optimizations to use (experimental: arm32) [default=auto]])],[req_asm=$withval], [req_asm=auto])
+[assembly to use (experimental: arm32) [default=auto]])],[req_asm=$withval], [req_asm=auto])
 
 AC_ARG_WITH([ecmult-window], [AS_HELP_STRING([--with-ecmult-window=SIZE|auto],
 [window size for ecmult precomputation for verification, specified as integer in range [2..24].]
@@ -279,24 +279,24 @@ else
   x86_64)
     SECP_X86_64_ASM_CHECK
     if test x"$has_x86_64_asm" != x"yes"; then
-      AC_MSG_ERROR([x86_64 assembly optimization requested but not available])
+      AC_MSG_ERROR([x86_64 assembly requested but not available])
     fi
     ;;
   arm32)
     SECP_ARM32_ASM_CHECK
     if test x"$has_arm32_asm" != x"yes"; then
-      AC_MSG_ERROR([ARM32 assembly optimization requested but not available])
+      AC_MSG_ERROR([ARM32 assembly requested but not available])
     fi
     ;;
   no)
     ;;
   *)
-    AC_MSG_ERROR([invalid assembly optimization selection])
+    AC_MSG_ERROR([invalid assembly selection])
     ;;
   esac
 fi
 
-# Select assembly optimization
+# Select assembly
 enable_external_asm=no
 
 case $set_asm in
@@ -309,7 +309,7 @@ arm32)
 no)
   ;;
 *)
-  AC_MSG_ERROR([invalid assembly optimizations])
+  AC_MSG_ERROR([invalid assembly selection])
   ;;
 esac
 
@@ -425,7 +425,7 @@ if test x"$enable_experimental" = x"yes"; then
   AC_MSG_NOTICE([******])
 else
   if test x"$set_asm" = x"arm32"; then
-    AC_MSG_ERROR([ARM32 assembly optimization is experimental. Use --enable-experimental to allow.])
+    AC_MSG_ERROR([ARM32 assembly is experimental. Use --enable-experimental to allow.])
   fi
 fi