Port fixes from bitcoin (#9)

* Port some fixes from bitcoin:
Mark more assembly outputs as early clobber #1307
Use more volatile in temporarties #1303
save normalize_weak calls in secp256k1_gej_eq_x_var #1344
remove random_field_element_test and use random_fe_test instead
upgrade CI to ubuntu22

* revert a change in secp256k1_gej_neg which generated incorrect signature
fix compiler warnings in tests

* upgrade CI to ubuntu22

* review feedback - fix documentation
remove secp256k1_fe_normalize_weak from secp256k1_ge_is_valid_var
port random_fe_non_zero_test and its usage

* review feedback - refactor random_fe_test usage. prefer using random_fe_non_zero_test instead of loop

.github/workflows/ci.yml

@@ -5,9 +5,9 @@ on: [push, pull_request]
 jobs:
   linux:
     name: "Linux"
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Build and test
         run: |
            ./autogen.sh

Makefile.am

@@ -38,7 +38,6 @@ 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/java/org_bitcoin_NativeSecp256k1.h
 noinst_HEADERS += src/java/org_bitcoin_Secp256k1Context.h
 noinst_HEADERS += src/util.h

configure.ac

@@ -1,4 +1,4 @@
-AC_PREREQ([2.60])
+AC_PREREQ([2.71])
 AC_INIT([libsecp256k1],[0.1])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_MACRO_DIR([build-aux/m4])
@@ -25,7 +25,7 @@ fi
 
 AM_PROG_CC_C_O
 
-AC_PROG_CC_C89
+AC_PROG_CC
 if test x"$ac_cv_prog_cc_c89" = x"no"; then
   AC_MSG_ERROR([c89 compiler support required])
 fi
@@ -149,7 +149,7 @@ AC_ARG_WITH([scalar], [AS_HELP_STRING([--with-scalar=64bit|32bit|auto],
 [Specify scalar implementation. Default is auto])],[req_scalar=$withval], [req_scalar=auto])
 
 AC_ARG_WITH([asm], [AS_HELP_STRING([--with-asm=x86_64|arm|no|auto]
-[Specify assembly optimizations to use. Default is auto (experimental: arm)])],[req_asm=$withval], [req_asm=auto])
+[Specify assembly to use. Default is auto (experimental: arm)])],[req_asm=$withval], [req_asm=auto])
 
 AC_CHECK_TYPES([__int128])
 
@@ -209,15 +209,15 @@ else
   x86_64)
     SECP_64BIT_ASM_CHECK
     if test x"$has_64bit_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
     ;;
   arm)
     ;;
   no)
     ;;
   *)
-    AC_MSG_ERROR([invalid assembly optimization selection])
+    AC_MSG_ERROR([invalid assembly selection])
     ;;
   esac
 fi
@@ -305,20 +305,20 @@ else
   esac
 fi
 
-# select assembly optimization
+# select assembly
 use_external_asm=no
 
 case $set_asm in
 x86_64)
-  AC_DEFINE(USE_ASM_X86_64, 1, [Define this symbol to enable x86_64 assembly optimizations])
+  AC_DEFINE(USE_ASM_X86_64, 1, [Define this symbol to enable x86_64 assembly])
   ;;
 arm)
   use_external_asm=yes
   ;;
 no)
   ;;
 *)
-  AC_MSG_ERROR([invalid assembly optimizations])
+  AC_MSG_ERROR([invalid assembly selection])
   ;;
 esac
 
@@ -442,7 +442,7 @@ if test x"$use_external_asm" = x"yes"; then
 fi
 
 AC_MSG_NOTICE([Using static precomputation: $set_precomp])
-AC_MSG_NOTICE([Using assembly optimizations: $set_asm])
+AC_MSG_NOTICE([Using assembly: $set_asm])
 AC_MSG_NOTICE([Using field implementation: $set_field])
 AC_MSG_NOTICE([Using bignum implementation: $set_bignum])
 AC_MSG_NOTICE([Using scalar implementation: $set_scalar])
@@ -463,7 +463,7 @@ else
     AC_MSG_ERROR([ECDH module is experimental. Use --enable-experimental to allow.])
   fi
   if test x"$set_asm" = x"arm"; then
-    AC_MSG_ERROR([ARM assembly optimization is experimental. Use --enable-experimental to allow.])
+    AC_MSG_ERROR([ARM assembly is experimental. Use --enable-experimental to allow.])
   fi
 fi