2015-11-23  Olivier Hainque  <hainque@adacore.com>
	    Eric Botcazou  <botcazou@adacore.com>

	* opt.ads (Exception_Mechanism): Now three values: Front_End_SJLJ,
	Back_End_SJLJ and Back_End_ZCX.
	(Back_End_Exceptions, Front_End_Exceptions, ZCX_Exceptions,
	SJLJ_Exceptions): New functions, reflecting properties of the current
	Exception_Mechanism.
	* opt.adb: Implement the new functions.
	* fe.h: Bind the new Exception_Mechanism and helper functions for gigi.

	* exp_ch11.adb (Expand_At_End_Handler): Replace test on mechanism by
	use of property helper and update comments.
	(Expand_Exception_Handlers): Replace tests on mechanism by use of
	helper. Restrict Abort_Defer to ZCX specifically.
	* exp_ch9.adb (Expand_N_Asynchronous_Select): Replace tests on
	mechanism by calls to helper functions. Abort_Undefer for ZCX only,
	paired with Expand_Exception_Handlers.
	* exp_sel.adb (Build_Abort_Block_Handler): Replace tests on mechanism
	by calls to helper functions. Abort_Undefer for ZCX only, paired with
	Expand_Exception_Handlers.

	* lib-writ.ads (P line documentation): Add entry for "FX",
	representative of unit compiled with Frontend_Exceptions True.
	* lib-writ.adb (Output_Main_Program_Line): Add "FX" on P line if
	compiled with Frontend_Exceptions True.

	* ali.ads (ALIs_Record): Ada a Frontend_Exceptions component, to reflect
	whether the ALI file contained an "FX" indication on the P line.
	(Frontend_Exceptions_Specified): New boolean, to keep track of whether
	at least an FX ALI file is in the closure.
	* ali.adb (Scan_ALI): Handle "FX" on the P line.
	(Initialize_ALI): Initialize Frontend_Exceptions_Specified to False.

	* targparm.ads: Update desription of exception schemes.
	(Frontend_Exceptions_On_Target): New flag, reflect Frontend_Exceptions
	set to True in system.ads, or not set at all.
	* targparm.adb (Targparm_Tags): Add FEX to convey Frontend_Exceptions.
	Rename ZCD to ZCX for consistency.
	(FEX_Str, Targparm_Str, Get_Target_Parameters): Adjust accordingly.

	* gnat1drv.adb (Adjust_Global_Switches): Adjust Exception_Mechanism
	setting, now from combination of Frontend_Exceptions and ZCX_By_Default.

	* bcheck.adb (Check_Consistent_Zero_Cost_Exception_Handling): Rename
	as ...
	(Check_Consistent_Exception_Handling): Check consistency of both
	ZCX_By_Default and Frontend_Exceptions.
	(Check_Configuration_Consistency): Check_Consistent_Exception_Handling
	if either flag was set at least once.

	* make.adb (Check): Remove processing of a possible -fsjlj coming from
	lang-specs.h.
	* gnatlink.adb (Gnatlin): Likewise.

	* gcc-interface/Makefile.in (gnatlib-sjlj/zcx): Now set
	both ZCX_By_Default and Frontend_Exceptions.
	* gcc-interface/decl.c (gnat_to_gnu_entity, case E_Variable):
	Use eh property helper to test for back-end exceptions. Adjust
	mechanism name when testing for front-end sjlj.
	(case E_Procedure): Likewise.
	* gcc-interface/trans.c (Handled_Sequence_Of_Statements_to_gnu):
	Likewise, and rename local variables.
	(Exception_Handler_to_gnu_sjlj): Rename as
	Exception_Handler_to_gnu_fe_sjlj.
	(Exception_Handler_to_gnu_zcx): Rename as
	Exception_Handler_to_gnu_gcc and adjust tests on eh mechanisms
	to use property helpers or correct mechanism name.


Co-Authored-By: Eric Botcazou <ebotcazou@adacore.com>

From-SVN: r230752