i386.md (logsf2, [...]): New patterns to implement log, logf and logl built-ins as...

i386.md (logsf2, [...]): New patterns to implement log, logf and logl built-ins as inline x87 intrinsics.

	* config/i386/i386.md (logsf2, logdf2, logxf2, logdf2): New patterns
	to implement log, logf and logl built-ins as inline x87 intrinsics.
	(UNSPEC_FYL2X): New unspec to represent x87's "fyl2x" instruction.
	(*fyl2x_sfxf3, *fyl2x_dfxf3, *fyl2x_xf3, *fyl2x_tfxf3): New insn
	patterns for x87's "fyl2x" instruction, used by log?f2 patterns.

	* reg-stack.c (subst_stack_regs_pat): Handle UNSPEC_FYL2X like
	UNSPEC_FPATAN, i.e. replaces two stack operands with single result.

	* gcc.dg/i386-387-1.c: Update to also test log.
	* gcc.dg/i386-387-2.c: Likewise.

From-SVN: r66709