commit 85e7de68bcfe6b137e0d4bb5fbfdc5f4a3db6a2d Author: Nick Mathewson <nickm@torproject.org> Date: Thu Apr 11 17:52:26 2013 -0400 Better test program for 128-bit math support Clang 3.2 does constant-folding and variable substitution to determine that the program is equivalent to "return 1". Splitting the 128-bit math into a new function seems sufficient to fix this. --- configure.ac | 40 +++++++++++++++++++++++----------------- 1 files changed, 23 insertions(+), 17 deletions(-) diff --git a/configure.ac b/configure.ac index 8a79653..6f40ac4 100644 --- a/configure.ac +++ b/configure.ac @@ -663,32 +663,38 @@ if test x$enable_curve25519 != xno; then [AC_LANG_PROGRAM([dnl #include <stdint.h> typedef unsigned uint128_t __attribute__((mode(TI))); - ], [dnl - uint64_t a = ((uint64_t)2000000000) * 1000000000; - uint64_t b = ((uint64_t)1234567890) << 24; - uint128_t c = ((uint128_t)a) * b; - int ok = ((uint64_t)(c>>96)) == 522859 && + int func(uint64_t a, uint64_t b) { + uint128_t c = ((uint128_t)a) * b; + int ok = ((uint64_t)(c>>96)) == 522859 && (((uint64_t)(c>>64))&0xffffffffL) == 3604448702L && (((uint64_t)(c>>32))&0xffffffffL) == 2351960064L && (((uint64_t)(c))&0xffffffffL) == 0; + return ok; + } + ], [dnl + int ok = func( ((uint64_t)2000000000) * 1000000000, + ((uint64_t)1234567890) << 24); return !ok; ])], [tor_cv_can_use_curve25519_donna_c64=yes], [tor_cv_can_use_curve25519_donna_c64=no], [AC_COMPILE_IFELSE( [AC_LANG_PROGRAM([dnl - #include <stdint.h> - typedef unsigned uint128_t __attribute__((mode(TI))); - ], [dnl - uint64_t a = ((uint64_t)2000000000) * 1000000000; - uint64_t b = ((uint64_t)1234567890) << 24; - uint128_t c = ((uint128_t)a) * b; - int ok = ((uint64_t)(c>>96)) == 522859 && - (((uint64_t)(c>>64))&0xffffffffL) == 3604448702L && - (((uint64_t)(c>>32))&0xffffffffL) == 2351960064L && - (((uint64_t)(c))&0xffffffffL) == 0; - return !ok; - ])], + #include <stdint.h> + typedef unsigned uint128_t __attribute__((mode(TI))); + int func(uint64_t a, uint64_t b) { + uint128_t c = ((uint128_t)a) * b; + int ok = ((uint64_t)(c>>96)) == 522859 && + (((uint64_t)(c>>64))&0xffffffffL) == 3604448702L && + (((uint64_t)(c>>32))&0xffffffffL) == 2351960064L && + (((uint64_t)(c))&0xffffffffL) == 0; + return ok; + } + ], [dnl + int ok = func( ((uint64_t)2000000000) * 1000000000, + ((uint64_t)1234567890) << 24); + return !ok; + ])], [tor_cv_can_use_curve25519_donna_c64=cross], [tor_cv_can_use_curve25519_donna_c64=no])])])