[Ada] Narrow large arithmetic and comparison operations

[Ada] Narrow large arithmetic and comparison operations

2020-06-18  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* exp_ch4.adb (Narrow_Large_Operation): New procedure to try
	and narrow large arithmetic and comparison operations.
	(Expand_N_In): Call it.
	(Expand_N_Op_Abs): Likewise.
	(Expand_N_Op_Add): Likewise.
	(Expand_N_Op_Divide): Likewise.
	(Expand_N_Op_Eq): Likewise.
	(Expand_N_Op_Ge): Likewise.
	(Expand_N_Op_Gt): Likewise.
	(Expand_N_Op_Le): Likewise.
	(Expand_N_Op_Lt): Likewise.
	(Expand_N_Op_Minus): Likewise.
	(Expand_N_Op_Mod): Likewise.
	(Expand_N_Op_Multiply): Likewise.
	(Expand_N_Op_Ne): Likewise.
	(Expand_N_Op_Plus): Likewise.
	(Expand_N_Op_Rem): Likewise.
	(Expand_N_Op_Subtract): Likewise.
	(Expand_N_Type_Conversion): Use Convert_To procedure.
	* exp_ch9.adb (Is_Pure_Barrier) <N_Identifier>: Skip all
	numeric types.
	<N_Type_Conversion>: Use explicit criterion.