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. Tested on x86_64-pc-linux-gnu, committed on trunk 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
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