re PR middle-end/29335 (transcendental functions with constant arguments should be...

re PR middle-end/29335 (transcendental functions with constant arguments should be resolved at compile-time)

	PR middle-end/29335
	* builtins.c (fold_builtin_cbrt, fold_builtin_logarithm):
	Calculate compile-time constants using MPFR.
	(fold_builtin_1): Likewise handle BUILT_IN_ERF, BUILT_IN_ERFC,
	BUILT_IN_EXPM1 and BUILT_IN_LOG1P.

testsuite:
	* gcc.dg/torture/builtin-math-2.c (TESTIT): Use new helper macro.
	Add checks for log, log2, log10 and log1p.

	* gcc.dg/torture/builtin-math-3.c: Add checks for -0.0 everywhere
	we already test 0.0.  Add checks for expm1, log, log2, log10,
	log1p, cbrt, erf and erfc.

From-SVN: r118042