[Patch 16/17 libgcc ARM] Half to double precision conversions

[Patch 16/17 libgcc ARM] Half to double precision conversions

gcc/

	* config/arm/arm.c (arm_convert_to_type): Delete.
	(TARGET_CONVERT_TO_TYPE): Delete.
	(arm_init_libfuncs): Enable trunc_optab from DFmode to HFmode.
	(arm_libcall_uses_aapcs_base): Add trunc_optab from DF- to HFmode.
	* config/arm/arm.h (TARGET_FP16_TO_DOUBLE): New.
	* config/arm/arm.md (truncdfhf2): Only convert through SFmode if we
	are in fast math mode, and have no single step hardware instruction.
	(extendhfdf2): Only expand through SFmode if we don't have a
	single-step hardware instruction.
	* config/arm/vfp.md (*truncdfhf2): New.
	(extendhfdf2): Likewise.

gcc/testsuite/

	* gcc.target/arm/fp16-rounding-alt-1.c (ROUNDED): Change expected
	result.
	* gcc.target/arm/fp16-rounding-ieee-1.c (ROUNDED): Change expected
	result.

From-SVN: r242783