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authorJustin Squirek <squirek@adacore.com>2022-08-31 14:52:11 +0000
committerMarc Poulhiès <poulhies@adacore.com>2022-09-12 10:16:51 +0200
commita968d80d0e89e847a1928842b7de166a6d42c92e (patch)
tree4190c36a86a777293a7ca1be5847c291b1eacd8a /gcc/ada/sem_ch6.adb
parent46ba7ae3c6eea45cc03de5fb00c8084cdc760d64 (diff)
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[Ada] Tech debt: Expansion of contracts
This patch modifies the expansion of contracts such that the statements and declarations of a subprogram with post-execution checks get moved to a local internally generated subprogram which the original subprogram calls directly followed by the required post-execution checks. This differs from the current implementation which requires delicate machinary which coordinates with the finalization process to emulate the desired behavior within the "at end" procedure. gcc/ada/ * contracts.adb, contracts.ads (Analyze_Pragmas_In_Declarations): Added to aid in the new expansion model so that pragmas relating to contracts can get processed early before the rest of the subprogram containing them. (Build_Subprogram_Contract_Wrapper): Created to do the majority of expansion for postconditions. It builds a local wrapper with the statements and declarations within a given subprogram. (Is_Prologue_Renaming): Moved out from Process_Preconditions to be used generally within the contracts package. (Build_Entry_Contract_Wrapper): Moved from exp_ch7. (Expand_Subprogram_Contract): Add new local variable Decls to store expanded declarations needed for evaluation of contracts. Call new wrapper building procedure and modify comments to match new expansion model. (Get_Postcond_Enabled): Deleted. (Get_Result_Object_For_Postcond): Deleted. (Get_Return_Success_For_Postcond): Deleted. (Process_Contract_Cases): Add new parameter to store declarations. (Process_Postconditions): Add new parameter to store declarations. (Process_Preconditions): Add new parameter to store declarations. Add code to move entry-call prologue renamings * einfo.ads: Document new field Wrapped_Statements and modify comment for Postconditions_Proc. * exp_attr.adb (Analyze_Attribute): Modify expansion of the 'Old attribute to recognize new expansion model and use Wrapped_Statements instead of Postconditions_Proc. * exp_ch6.adb (Add_Return): Remove special expansion for postconditions. (Expand_Call): Modify condition checking for calls to access subprogram wrappers to handle new expansion models. (Expand_Call_Helper): Remove special expansion for postconditions. (Expand_Non_Function_Return): Remove special expansion for postconditions. (Expand_Simple_Function_Return): Remove special expansion for postconditions. * exp_ch7.adb (Build_Finalizer): Deleted, but replaced by code in Build_Finalizer_Helper (Build_Finalizer_Helper): Renamed to Build_Finalizer, and special handling of 'Old objects removed. * exp_ch9.adb (Build_Contract_Wrapper): Renamed and moved to contracts package. * exp_prag.adb (Expand_Pragma_Contract_Cases): Delay analysis of contracts since they now instead get analyzed as part of the wrapper generation instead of after analysis of their corresponding subprogram's body. (Expand_Pragma_Check): Label expanded if-statements which come from the expansion of assertion statements as Comes_From_Check_Or_Contract. * freeze.adb (Freeze_Entity): Add special case to avoid freezing when a freeze node gets generated as part of the expansion of a postcondition check. * gen_il-gen-gen_nodes.adb: Add new flag Comes_From_Check_Or_Contract. * gen_il-fields.ads: Add new field Wrapped_Statements. Add new flag Comes_From_Check_Or_Contract. * gen_il-gen-gen_entities.adb: Add new field Wrapped_Statements. * ghost.adb (Is_OK_Declaration): Replace Name_uPostconditions with Name_uWrapped_Statements. (Is_OK_Statement): Simplify condition due to the loss of Original_Node as a result of the new expansion model of contracts and use new flag Comes_From_Check_Or_Contract in its place. * inline.adb (Declare_Postconditions_Result): Replace Name_uPostconditions with Name_uWrapped_Statements. (Expand_Inlined_Call): Replace Name_uPostconditions with Name_uWrapped_Statements. * lib.adb, lib.ads (ipu): Created to aid in debugging. * lib-xref.adb (Generate_References): Remove special handling for postcondition procedures. * sem_attr.adb (Analyze_Attribute_Old_Result): Add new context in which 'Old can appear due to the changes in expansion. Replace Name_uPostconditions with Name_uWrapped_Statements. (Result): Replace Name_uPostconditions with Name_uWrapped_Statements. * sem_ch11.adb (Analyze_Handled_Statements): Remove check to exclude warnings on useless assignments within postcondition procedures since postconditions no longer get isolated into separate subprograms. * sem_ch6.adb (Analyze_Generic_Subprogram_Body): Modify expansion of generic subprogram bodies so that contracts (and their associated pragmas) get analyzed first. (Analyze_Subprogram_Body_Helper): Remove global HSS variable due to the HSS of the body potentially changing during the expansion of contracts. In cases where it was used instead directly call Handled_Statement_Sequence. Modify expansion of subprogram bodies so that contracts (and their associated pragmas) get analyzed first. (Check_Missing_Return): Create local HSS variable instead of using a global one. (Move_Pragmas): Use new pragma table instead of an explicit list. * sem_elab.adb (Is_Postconditions_Proc): Deleted since the new scheme of expansion no longer divides postcondition checks to a separate subprogram and so cannot be easily identified (similar to pre-condition checks). (Info_Call): Remove info printing for _Postconditions subprograms. (Is_Assertion_Pragma_Target): Remove check for postconditions procedure (Is_Bridge_Target): Remove check for postconditions procedure. (Get_Invocation_Attributes): Remove unneeded local variables and check for postconditions procedure. (Output_Call): Remove info printing for _Postconditions subprograms. * sem_prag.adb, sem_prag.ads: Add new Pragma table for pragmas significant to subprograms, along with tech-debt comment. (Check_Arg_Is_Local_Name): Modified to recognize the new _Wrapped_Statements internal subprogram and the new expansion model. (Relocate_Pragmas_To_Body): Replace Name_uPostconditions with Name_uWrapped_Statements. * sem_res.adb (Resolve_Entry_Call): Add conditional to detect both contract based wrappers of entries, but also wrappers generated as part of general contract expansion (e.g. local postconditions subprograms). * sem_util.adb (Accessibility_Level): Verify 'Access is not taken based on a component of a function result. (Has_Significant_Contracts): Replace Name_uPostconditions with Name_uWrapped_Statements. (Same_Or_Aliased_Subprogram): Add conditional to detect and obtain the original subprogram based on the new concept of "postcondition" wrappers. * sinfo.ads: Add documentation for new flag Comes_From_Check_Or_Contract. * snames.ads-tmpl: Remove Name_uPostconditions and add Name_uWrapped_Statements
Diffstat (limited to 'gcc/ada/sem_ch6.adb')
-rw-r--r--gcc/ada/sem_ch6.adb85
1 files changed, 39 insertions, 46 deletions
diff --git a/gcc/ada/sem_ch6.adb b/gcc/ada/sem_ch6.adb
index 93eeecb..0459058 100644
--- a/gcc/ada/sem_ch6.adb
+++ b/gcc/ada/sem_ch6.adb
@@ -1911,15 +1911,19 @@ package body Sem_Ch6 is
Analyze_Aspects_On_Subprogram_Body_Or_Stub (N);
end if;
- Analyze_Declarations (Declarations (N));
- Check_Completion;
-
- -- Process the contract of the subprogram body after all declarations
- -- have been analyzed. This ensures that any contract-related pragmas
- -- are available through the N_Contract node of the body.
+ -- Process the contract of the subprogram body after analyzing all
+ -- the contract-related pragmas within the declarations.
+ Analyze_Pragmas_In_Declarations (Body_Id);
Analyze_Entry_Or_Subprogram_Body_Contract (Body_Id);
+ -- Continue on with analyzing the declarations and statements once
+ -- contract expansion is done and we are done expanding contract
+ -- related wrappers.
+
+ Analyze_Declarations (Declarations (N));
+ Check_Completion;
+
Analyze (Handled_Statement_Sequence (N));
Save_Global_References (Original_Node (N));
@@ -2895,7 +2899,6 @@ package body Sem_Ch6 is
Conformant : Boolean;
Desig_View : Entity_Id := Empty;
Exch_Views : Elist_Id := No_Elist;
- HSS : Node_Id;
Mask_Types : Elist_Id := No_Elist;
Prot_Typ : Entity_Id := Empty;
Spec_Decl : Node_Id := Empty;
@@ -3530,6 +3533,8 @@ package body Sem_Ch6 is
--------------------------
procedure Check_Missing_Return is
+ HSS : constant Node_Id := Handled_Statement_Sequence (N);
+
Id : Entity_Id;
Missing_Ret : Boolean;
@@ -3968,18 +3973,9 @@ package body Sem_Ch6 is
-- Move relevant pragmas to the spec
- elsif Pragma_Name_Unmapped (Decl) in Name_Depends
- | Name_Ghost
- | Name_Global
- | Name_Pre
- | Name_Precondition
- | Name_Post
- | Name_Refined_Depends
- | Name_Refined_Global
- | Name_Refined_Post
- | Name_Inline
- | Name_Pure_Function
- | Name_Volatile_Function
+ elsif
+ Pragma_Significant_To_Subprograms
+ (Get_Pragma_Id (Decl))
then
Remove (Decl);
Insert_After (Insert_Nod, Decl);
@@ -4223,7 +4219,6 @@ package body Sem_Ch6 is
Analyze_Generic_Subprogram_Body (N, Spec_Id);
if Nkind (N) = N_Subprogram_Body then
- HSS := Handled_Statement_Sequence (N);
Check_Missing_Return;
end if;
@@ -5157,9 +5152,27 @@ package body Sem_Ch6 is
end;
end if;
- -- Now we can go on to analyze the body
+ -- Ada 2012 (AI05-0151): Incomplete types coming from a limited context
+ -- may now appear in parameter and result profiles. Since the analysis
+ -- of a subprogram body may use the parameter and result profile of the
+ -- spec, swap any limited views with their non-limited counterpart.
+
+ if Ada_Version >= Ada_2012 and then Present (Spec_Id) then
+ Exch_Views := Exchange_Limited_Views (Spec_Id);
+ end if;
+
+ -- Analyze any aspect specifications that appear on the subprogram body
+
+ if Has_Aspects (N) then
+ Analyze_Aspects_On_Subprogram_Body_Or_Stub (N);
+ end if;
+
+ -- Process the contract of the subprogram body after analyzing all the
+ -- contract-related pragmas within the declarations.
+
+ Analyze_Pragmas_In_Declarations (Body_Id);
+ Analyze_Entry_Or_Subprogram_Body_Contract (Body_Id);
- HSS := Handled_Statement_Sequence (N);
Set_Actual_Subtypes (N, Current_Scope);
-- Add a declaration for the Protection object, renaming declarations
@@ -5180,15 +5193,6 @@ package body Sem_Ch6 is
(Sloc (N), Spec_Id, Prot_Typ, N, Declarations (N));
end if;
- -- Ada 2012 (AI05-0151): Incomplete types coming from a limited context
- -- may now appear in parameter and result profiles. Since the analysis
- -- of a subprogram body may use the parameter and result profile of the
- -- spec, swap any limited views with their non-limited counterpart.
-
- if Ada_Version >= Ada_2012 and then Present (Spec_Id) then
- Exch_Views := Exchange_Limited_Views (Spec_Id);
- end if;
-
-- If the return type is an anonymous access type whose designated type
-- is the limited view of a class-wide type and the non-limited view is
-- available, update the return type accordingly.
@@ -5225,12 +5229,6 @@ package body Sem_Ch6 is
end;
end if;
- -- Analyze any aspect specifications that appear on the subprogram body
-
- if Has_Aspects (N) then
- Analyze_Aspects_On_Subprogram_Body_Or_Stub (N);
- end if;
-
Analyze_Declarations (Declarations (N));
-- Verify that the SPARK_Mode of the body agrees with that of its spec
@@ -5269,17 +5267,11 @@ package body Sem_Ch6 is
end if;
end if;
- -- A subprogram body freezes its own contract. Analyze the contract
- -- after the declarations of the body have been processed as pragmas
- -- are now chained on the contract of the subprogram body.
-
- Analyze_Entry_Or_Subprogram_Body_Contract (Body_Id);
-
-- Check completion, and analyze the statements
Check_Completion;
Inspect_Deferred_Constant_Completion (Declarations (N));
- Analyze (HSS);
+ Analyze (Handled_Statement_Sequence (N));
-- Add the generated minimum accessibility objects to the subprogram
-- body's list of declarations after analysis of the statements and
@@ -5296,7 +5288,8 @@ package body Sem_Ch6 is
-- Deal with end of scope processing for the body
- Process_End_Label (HSS, 't', Current_Scope);
+ Process_End_Label
+ (Handled_Statement_Sequence (N), 't', Current_Scope);
Update_Use_Clause_Chain;
End_Scope;
@@ -5410,7 +5403,7 @@ package body Sem_Ch6 is
-- the warning.
declare
- Stm : Node_Id := First (Statements (HSS));
+ Stm : Node_Id := First (Statements (Handled_Statement_Sequence (N)));
begin
-- Skip call markers installed by the ABE mechanism, labels, and
-- Push_xxx_Error_Label to find the first real statement.