Conditionalize constant folding of math intrinsics on the availability of an implementation on the host.  This is a little bit unfortunate, but until someone decides to implement a full libm for APFloat, we don't have a better way to get this functionality.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174561 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index c1f2884..ae615df 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -1573,6 +1573,7 @@
 
 AC_CHECK_FUNCS([backtrace ceilf floorf roundf rintf nearbyintf getcwd ])
 AC_CHECK_FUNCS([powf fmodf strtof round ])
+AC_CHECK_FUNCS([log log2 log10 exp exp2])
 AC_CHECK_FUNCS([getpagesize getrusage getrlimit setrlimit gettimeofday ])
 AC_CHECK_FUNCS([isatty mkdtemp mkstemp ])
 AC_CHECK_FUNCS([mktemp posix_spawn pread realpath sbrk setrlimit strdup ])