[Ada] Generation of procedures for blocks occurring in elaboration code for LLVM

[Ada] Generation of procedures for blocks occurring in elaboration code for LLVM

2019-10-10  Gary Dismukes  <dismukes@adacore.com>

gcc/ada/

	* exp_ch7.adb (Check_Unnesting_Elaboration_Code): Various
	cleanups.
	(Set_Elab_Proc): New procedure to create the defining identifier
	for a procedure created to encapsulate top-level blocks
	occurring as a part of library package elaboration.
	(First_Local_Scope): Function replaced by
	Reset_Scopes_To_Elab_Proc.
	(Reset_Scopes_To_Elab_Proc): New recursive procedure based on
	First_Local_Scope, which it replaces, that is called to traverse
	the statements of a library package body to locate top-level
	blocks and determine whether they contain nested subprograms
	that might address library-level objects of the package. Such
	blocks (and loops) and certain top-level subprograms within the
	statements will have their Scope reset here to match an
	encapsulating procedure created by
	Check_Unnesting_Elaboration_Code that will contain the
	statements.
	(Check_Unnesting_In_Decls_Or_Stmts): Code for handling blocks
	factored out into Unnest_Block. Add handling for package
	declarations and bodies, making recursive calls for
	visible/private declarations, body declarations, statements, and
	exception handlers. Also remove test for Is_Compilation_Unit:
	caller tests for Is_Library_Level_Entity instead.  Also, this
	proc's name was changed from Check_Unnesting_In_Declarations.
	(Check_Unnesting_In_Handlers): New procedure to traverse a
	sequence of exception handlers, calling
	Check_Unnesting_In_Decls_Or_Stmts on the statements of each
	handler.
	(Expand_N_Package_Body): Call Check_Unnesting_* routines only
	when Unnest_Subprogram_Mode is set and the current scope is a
	library-level entity (which includes packages and instantiations
	nested directly within a library unit).
	(Expand_N_Package_Declaration): Call Check_Unnesting_* routines
	only when Unnest_Subprogram_Mode is set and the current scope is
	a library-level entity (which includes packages and
	instantiations nested directly within a library unit).
	(Unnest_Block): New procedure factored out of
	Check_Unnesting_In_Decls_Or_Stmts, for creating a new procedure
	to replace a block statement and resetting the Scope fields of
	the block's top-level entities.

From-SVN: r276816