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sem.adb (Analyze): Consider case in which we analyze an empty node that was generated by a call to... 

2008-04-08  Javier Miranda  <miranda@adacore.com>

	* sem.adb (Analyze): Consider case in which we analyze an empty node
	that was generated by a call to a runtime function that is not
	available under the configurable runtime.

	* sem.ads (Inside_Freezing_Actions): New flag.
	(Save_Check_Policy_List): New field in scope stack entry

From-SVN: r134048
This commit is contained in:
Javier Miranda 2008-04-08 08:54:53 +02:00 committed by Arnaud Charlet
parent 7f2401a678
commit f89b7956cb
2 changed files with 103 additions and 81 deletions
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39
gcc/ada/sem.adb
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@ -6,7 +6,7 @@
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
-- Copyright (C) 1992-2008, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@ -547,8 +547,12 @@ package body Sem is
-- been any other errors, we just ignore it, otherwise it is
-- a real internal error which we complain about.
-- We must also consider the case of call to a runtime function
-- that is not available in the configurable runtime.
when N_Empty =>
pragma Assert (Serious_Errors_Detected /= 0);
pragma Assert (Serious_Errors_Detected /= 0
or else Configurable_Run_Time_Violations /= 0);
null;
-- A call to analyze the error node is simply ignored, to avoid
@ -1275,14 +1279,14 @@ package body Sem is
-- values for these variables, and also that such calls do not
-- disturb the settings for units being analyzed at a higher level.
S_Current_Sem_Unit : constant Unit_Number_Type := Current_Sem_Unit;
S_Full_Analysis : constant Boolean := Full_Analysis;
S_In_Default_Expr : constant Boolean := In_Default_Expression;
S_GNAT_Mode : constant Boolean := GNAT_Mode;
S_Global_Dis_Names : constant Boolean := Global_Discard_Names;
S_In_Spec_Expr : constant Boolean := In_Spec_Expression;
S_Inside_A_Generic : constant Boolean := Inside_A_Generic;
S_New_Nodes_OK : constant Int := New_Nodes_OK;
S_Outer_Gen_Scope : constant Entity_Id := Outer_Generic_Scope;
S_Sem_Unit : constant Unit_Number_Type := Current_Sem_Unit;
S_GNAT_Mode : constant Boolean := GNAT_Mode;
S_Discard_Names : constant Boolean := Global_Discard_Names;
Generic_Main : constant Boolean :=
Nkind (Unit (Cunit (Main_Unit)))
@ -1356,9 +1360,9 @@ package body Sem is
(Operating_Mode = Generate_Code or Debug_Flag_X);
end if;
Full_Analysis := True;
Inside_A_Generic := False;
In_Default_Expression := False;
Full_Analysis := True;
Inside_A_Generic := False;
In_Spec_Expression := False;
Set_Comes_From_Source_Default (False);
Save_Opt_Config_Switches (Save_Config_Switches);
@ -1389,17 +1393,16 @@ package body Sem is
-- Restore settings of saved switches to entry values
Current_Sem_Unit := S_Sem_Unit;
Full_Analysis := S_Full_Analysis;
In_Default_Expression := S_In_Default_Expr;
Inside_A_Generic := S_Inside_A_Generic;
New_Nodes_OK := S_New_Nodes_OK;
Outer_Generic_Scope := S_Outer_Gen_Scope;
GNAT_Mode := S_GNAT_Mode;
Global_Discard_Names := S_Discard_Names;
Current_Sem_Unit := S_Current_Sem_Unit;
Full_Analysis := S_Full_Analysis;
Global_Discard_Names := S_Global_Dis_Names;
GNAT_Mode := S_GNAT_Mode;
In_Spec_Expression := S_In_Spec_Expr;
Inside_A_Generic := S_Inside_A_Generic;
New_Nodes_OK := S_New_Nodes_OK;
Outer_Generic_Scope := S_Outer_Gen_Scope;
Restore_Opt_Config_Switches (Save_Config_Switches);
Expander_Mode_Restore;
end Semantics;
end Sem;

145
gcc/ada/sem.ads
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@ -6,7 +6,7 @@
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
-- Copyright (C) 1992-2008, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
@ -84,31 +84,37 @@
-- Analysis-Resolution-Expansion model for expressions. The most prominent
-- examples are the handling of default expressions and aggregates.
----------------------------------------------------
-- Handling of Default and Per-Object Expressions --
----------------------------------------------------
-----------------------------------------------------------------------
-- Handling of Default and Per-Object Expressions (Spec-Expressions) --
-----------------------------------------------------------------------
-- The default expressions in component declarations and in procedure
-- specifications (but not the ones in object declarations) are quite
-- tricky to handle. The problem is that some processing is required
-- at the point where the expression appears:
-- specifications (but not the ones in object declarations) are quite tricky
-- to handle. The problem is that some processing is required at the point
-- where the expression appears:
-- visibility analysis (including user defined operators)
-- freezing of static expressions
-- but other processing must be deferred until the enclosing entity
-- (record or procedure specification) is frozen:
-- but other processing must be deferred until the enclosing entity (record or
-- procedure specification) is frozen:
-- freezing of any other types in the expression
-- expansion
-- freezing of any other types in the expression expansion
-- generation of code
-- A similar situation occurs with the argument of priority and interrupt
-- priority pragmas that appear in task and protected definition specs and
-- other cases of per-object expressions (see RM 3.8(18)).
-- Expansion has to be deferred since you can't generate code for
-- expressions that refernce types that have not been frozen yet. As an
-- example, consider the following:
-- Another similar case is the conditions in precondition and postcondition
-- pragmas that appear with subprogram specifications rather than in the body.
-- Collectively we call these Spec_Expressions. The routine that performs the
-- special analysis is called Analyze_Spec_Expression.
-- Expansion has to be deferred since you can't generate code for expressions
-- that reference types that have not been frozen yet. As an example, consider
-- the following:
-- type x is delta 0.5 range -10.0 .. +10.0;
-- ...
@ -118,9 +124,9 @@
-- for x'small use 0.25
-- The expander is in charge of dealing with fixed-point, and of course
-- the small declaration, which is not too late, since the declaration of
-- type q does *not* freeze type x, definitely affects the expanded code.
-- The expander is in charge of dealing with fixed-point, and of course the
-- small declaration, which is not too late, since the declaration of type q
-- does *not* freeze type x, definitely affects the expanded code.
-- Another reason that we cannot expand early is that expansion can generate
-- range checks. These range checks need to be inserted not at the point of
@ -132,26 +138,27 @@
-- this is the one case where this model falls down. Here is how we patch
-- it up without causing too much distortion to our basic model.
-- A switch (sede below) is set to indicate that we are in the initial
-- A switch (In_Spec_Expression) is set to show that we are in the initial
-- occurence of a default expression. The analyzer is then called on this
-- expression with the switch set true. Analysis and resolution proceed
-- almost as usual, except that Freeze_Expression will not freeze
-- non-static expressions if this switch is set, and the call to Expand at
-- the end of resolution is skipped. This also skips the code that normally
-- sets the Analyzed flag to True). The result is that when we are done the
-- tree is still marked as unanalyzed, but all types for static expressions
-- are frozen as required, and all entities of variables have been
-- recorded. We then turn off the switch, and later on reanalyze the
-- expression with the switch off. The effect is that this second analysis
-- freezes the rest of the types as required, and generates code but
-- visibility analysis is not repeated since all the entities are marked.
-- expression with the switch set true. Analysis and resolution proceed almost
-- as usual, except that Freeze_Expression will not freeze non-static
-- expressions if this switch is set, and the call to Expand at the end of
-- resolution is skipped. This also skips the code that normally sets the
-- Analyzed flag to True. The result is that when we are done the tree is
-- still marked as unanalyzed, but all types for static expressions are frozen
-- as required, and all entities of variables have been recorded. We then turn
-- off the switch, and later on reanalyze the expression with the switch off.
-- The effect is that this second analysis freezes the rest of the types as
-- required, and generates code but visibility analysis is not repeated since
-- all the entities are marked.
-- The second analysis (the one that generates code) is in the context
-- where the code is required. For a record field default, this is in
-- the initialization procedure for the record and for a subprogram
-- default parameter, it is at the point the subprogram is frozen.
-- For a priority or storage size pragma it is in the context of the
-- Init_Proc for the task or protected object.
-- where the code is required. For a record field default, this is in the
-- initialization procedure for the record and for a subprogram default
-- parameter, it is at the point the subprogram is frozen. For a priority or
-- storage size pragma it is in the context of the Init_Proc for the task or
-- protected object. For a pre/postcondition pragma it is in the body when
-- code for the pragma is generated.
------------------
-- Pre-Analysis --
@ -164,34 +171,35 @@
--
-- (1 .. 100 => new Thing (Function_Call))
--
-- The normal Analysis-Resolution-Expansion mechanism where expansion
-- of the children is performed before expansion of the parent does not
-- work if the code generated for the children by the expander needs
-- to be evaluated repeatdly (for instance in the above aggregate
-- "new Thing (Function_Call)" needs to be called 100 times.)
-- The reason why this mecanism does not work is that, the expanded code
-- for the children is typically inserted above the parent and thus
-- when the father gets expanded no re-evaluation takes place. For instance
-- in the case of aggregates if "new Thing (Function_Call)" is expanded
-- before of the aggregate the expanded code will be placed outside
-- of the aggregate and when expanding the aggregate the loop from 1 to 100
-- will not surround the expanded code for "new Thing (Function_Call)".
--
-- To remedy this situation we introduce a new flag which signals whether
-- we want a full analysis (ie expansion is enabled) or a pre-analysis
-- which performs Analysis and Resolution but no expansion.
--
-- After the complete pre-analysis of an expression has been carried out
-- we can transform the expression and then carry out the full
-- Analyze-Resolve-Expand cycle on the transformed expression top-down
-- so that the expansion of inner expressions happens inside the newly
-- generated node for the parent expression.
--
-- The normal Analysis-Resolution-Expansion mechanism where expansion of the
-- children is performed before expansion of the parent does not work if the
-- code generated for the children by the expander needs to be evaluated
-- repeatdly (for instance in the above aggregate "new Thing (Function_Call)"
-- needs to be called 100 times.)
-- The reason why this mecanism does not work is that, the expanded code for
-- the children is typically inserted above the parent and thus when the
-- father gets expanded no re-evaluation takes place. For instance in the case
-- of aggregates if "new Thing (Function_Call)" is expanded before of the
-- aggregate the expanded code will be placed outside of the aggregate and
-- when expanding the aggregate the loop from 1 to 100 will not surround the
-- expanded code for "new Thing (Function_Call)".
-- To remedy this situation we introduce a new flag which signals whether we
-- want a full analysis (ie expansion is enabled) or a pre-analysis which
-- performs Analysis and Resolution but no expansion.
-- After the complete pre-analysis of an expression has been carried out we
-- can transform the expression and then carry out the full three stage
-- (Analyze-Resolve-Expand) cycle on the transformed expression top-down so
-- that the expansion of inner expressions happens inside the newly generated
-- node for the parent expression.
-- Note that the difference between processing of default expressions and
-- pre-analysis of other expressions is that we do carry out freezing in
-- the latter but not in the former (except for static scalar expressions).
-- The routine that performs pre-analysis is called Pre_Analyze_And_Resolve
-- and is in Sem_Res.
-- The routine that performs preanalysis and corresponding resolution is
-- called Preanalyze_And_Resolve and is in Sem_Res.
with Alloc;
with Einfo; use Einfo;
@ -223,8 +231,8 @@ package Sem is
-- whether expansion is currently enabled). You should really regard this
-- as a read only flag.
In_Default_Expression : Boolean := False;
-- Switch to indicate that we are in a default expression, as described
In_Spec_Expression : Boolean := False;
-- Switch to indicate that we are in a spec-expression, as described
-- above. Note that this must be recursively saved on a Semantics call
-- since it is possible for the analysis of an expression to result in a
-- recursive call (e.g. to get the entity for System.Address as part of the
@ -252,14 +260,22 @@ package Sem is
-- package Expander). Only the generic processing can modify the
-- status of this flag, any other client should regard it as read-only.
Inside_Freezing_Actions : Nat := 0;
-- Flag indicating whether we are within a call to Expand_N_Freeze_Actions.
-- Non-zero means we are inside (it is actually a level counter to deal
-- with nested calls). Used to avoid traversing the tree each time a
-- subprogram call is processed to know if we must not clear all constant
-- indications from entities in the current scope. Only the expansion of
-- freezing nodes can modify the status of this flag, any other client
-- should regard it as read-only.
Unloaded_Subunits : Boolean := False;
-- This flag is set True if we have subunits that are not loaded. This
-- occurs when the main unit is a subunit, and contains lower level
-- subunits that are not loaded. We use this flag to suppress warnings
-- about unused variables, since these warnings are unreliable in this
-- case. We could perhaps do a more accurate job and retain some of the
-- warnings, but it is quite a tricky job. See test 4323-002.
-- Should not reference TN's in the source comments ???
-- warnings, but it is quite a tricky job.
-----------------------------------
-- Handling of Check Suppression --
@ -442,6 +458,9 @@ package Sem is
Save_Local_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
-- Save contents of Local_Suppress_Stack on entry to restore on exit
Save_Check_Policy_List : Node_Id;
-- Save contents of Check_Policy_List on entry to restore on exit
Is_Transient : Boolean;
-- Marks Transient Scopes (See Exp_Ch7 body for details)