Code using "long double" on x86_64 will compile to x87 instructions (at least with GCC on Linux). This can be triggered unintentionally. For example, string-to

Code using "long double" on x86_64 will compile to x87 instructions (at least with GCC on Linux). This can be triggered unintentionally. For example, string-to-double conversions in Boost use long doubles. (I have been bitten by that when using valgrind: Valgrind emulates x87 80-bit registers using 64-bit doubles. As a result, some Boost-using code will have a different behavior under valgrind.)