Refactor handling of not instrumented obligations

We had different ways of dealing with not instrumented statements, and
decisions / conditions. Unify both for clarity purposes.

Also move parts of the not instrumented obligations handling to
Instrument.Common, to be able to use it in Instrument.C, as we will need
it for constexpr code constructs.

Author: Jugst3r

tools/gnatcov/decision_map.adb

@@ -80,8 +80,6 @@ package body Decision_Map is
    --  Return the PC of the first conditional branch instruction in D_Occ.
    --  Used as unique identifier for occurrences.
 
-   package SCO_Sets is new Ada.Containers.Ordered_Sets (SCO_Id);
-
    type Call_Kind is (Normal, Raise_Exception, Finalizer);
    --  Classification of calls within a decision:
    --    - normal calls to subprograms

tools/gnatcov/instrument-ada_unit.adb

@@ -96,11 +96,6 @@ package body Instrument.Ada_Unit is
       return Ada_Qualified_Name;
    --  Convert a Libadalang fully qualified name into our format
 
-   procedure Import_Non_Instrumented_LL_SCOs
-     (UIC : Ada_Unit_Inst_Context; SCO_Map : LL_HL_SCO_Map);
-   --  Import the low level SCO in UIC marked as non-instrumented in the high
-   --  level non-instrumented SCO_Id sets.
-
    procedure Find_Ada_Units
      (Instrumenter : in out Ada_Instrumenter_Type;
       Filename     : String;
@@ -165,29 +160,6 @@ package body Instrument.Ada_Unit is
       end return;
    end To_Qualified_Name;
 
-   -------------------------------------
-   -- Import_Non_Instrumented_LL_SCOs --
-   -------------------------------------
-
-   procedure Import_Non_Instrumented_LL_SCOs
-     (UIC : Ada_Unit_Inst_Context; SCO_Map : LL_HL_SCO_Map) is
-   begin
-      for LL_SCO of UIC.Non_Instr_LL_SCOs loop
-         declare
-            Remapped_SCO : constant SCO_Id := SCO_Map (Nat (LL_SCO));
-         begin
-            case Kind (Remapped_SCO) is
-               when Statement => Set_Stmt_SCO_Non_Instr (Remapped_SCO);
-               when Decision  => Set_Decision_SCO_Non_Instr (Remapped_SCO);
-               when Condition => Set_Decision_SCO_Non_Instr_For_MCDC
-                                   (Enclosing_Decision (Remapped_SCO));
-               when others =>
-                  null;
-            end case;
-         end;
-      end loop;
-   end Import_Non_Instrumented_LL_SCOs;
-
    type All_Symbols is
      (
       --  Aspects
@@ -2972,8 +2944,8 @@ package body Instrument.Ada_Unit is
    --  top level).
    --
    --  If Do_Not_Instrument, this creates SCOs for the decisions/conditions,
-   --  but plan not to instrument them, so that the decision can be reported as
-   --  such.
+   --  but plans not to instrument them, so that the decision can be reported
+   --  as such.
 
    --------------------------
    -- Internal Subprograms --
@@ -3067,6 +3039,10 @@ package body Instrument.Ada_Unit is
 
       In_Generic : Boolean := False;
       --  Wether this statment is generic code.
+
+      Do_Not_Instrument : Boolean;
+      --  Whether this statement should not be instrumented. This is set to
+      --  True when instrumenting the statement could create invalid Ada code.
    end record;
 
    package SC is new Table.Table
@@ -3126,16 +3102,16 @@ package body Instrument.Ada_Unit is
       SD_First : constant Nat := SD.Last + 1;
       --  Record first entries used in SC/SD at this recursive level
 
-      Current_Insertion_Info : aliased Insertion_Info :=
-        (Method => None, Unsupported => False);
+      Current_Insertion_Info : aliased Insertion_Info := (Method => None);
 
       procedure Extend_Statement_Sequence
         (UIC                 : Ada_Unit_Inst_Context;
          N                   : Ada_Node'Class;
          Typ                 : Character;
          Insertion_N         : Node_Rewriting_Handle :=
                                   No_Node_Rewriting_Handle;
-         Instrument_Location : Instrument_Location_Type := Before);
+         Instrument_Location : Instrument_Location_Type := Before;
+         Do_Not_Instrument   : Boolean := False);
       --  Extend the current statement sequence to encompass the node N.
       --
       --  Typ is the letter that identifies the type of statement/declaration
@@ -3206,7 +3182,8 @@ package body Instrument.Ada_Unit is
          Typ                 : Character;
          Insertion_N         : Node_Rewriting_Handle :=
                                   No_Node_Rewriting_Handle;
-         Instrument_Location : Instrument_Location_Type := Before)
+         Instrument_Location : Instrument_Location_Type := Before;
+         Do_Not_Instrument   : Boolean := False)
       is
          SR      : constant Source_Location_Range := N.Sloc_Range;
 
@@ -3344,7 +3321,8 @@ package body Instrument.Ada_Unit is
                         when others        => After)
                 else Instrument_Location),
 
-             In_Generic          => UIC.In_Generic));
+             In_Generic          => UIC.In_Generic,
+             Do_Not_Instrument   => Do_Not_Instrument));
       end Extend_Statement_Sequence;
 
       -----------------------------
@@ -3442,12 +3420,7 @@ package body Instrument.Ada_Unit is
 
             Raise_Stub_Internal_Error_For (Ada_Instrument_Insert_Stmt_Witness);
 
-            --  If the current code pattern is actually unsupported, do not
-            --  even try to insert the witness call or allocate bits for it in
-            --  the buffers. Mark the corresponding SCO as non-instrumented
-            --  instead.
-
-            if Insert_Info.Unsupported then
+            if SCE.Do_Not_Instrument then
                UIC.Non_Instr_LL_SCOs.Include (SCO_Id (LL_SCO_Id));
                return;
             end if;
@@ -3863,7 +3836,6 @@ package body Instrument.Ada_Unit is
          begin
 
             II.RH_List := Stmt_list_RH;
-            II.Unsupported := False;
             II.Index := 1;
             II.Rewriting_Offset := 0;
             II.Preelab := False;
@@ -3951,8 +3923,7 @@ package body Instrument.Ada_Unit is
          --  Witness insertion info for statements (for both null procedures
          --  and expression functions).
 
-         Unsupported : Boolean := False;
-         --  Temporary to compute New_Insertion_Info.Unsupported
+         Do_Not_Instrument : Boolean := False;
 
          EF_Inserter : aliased Expr_Func_MCDC_State_Inserter :=
            (N_Spec        => N_Spec,
@@ -3989,7 +3960,7 @@ package body Instrument.Ada_Unit is
 
          if Is_Generic (UIC, N.As_Basic_Decl) then
             if Is_Expr_Function then
-               Unsupported := True;
+               Do_Not_Instrument := True;
                Report (UIC, N,
                        "gnatcov limitation: "
                        & "cannot instrument generic expression functions."
@@ -4000,7 +3971,7 @@ package body Instrument.Ada_Unit is
                --  functions and null procedures, we are in the case of a
                --  generic null procedure here.
 
-               Unsupported := True;
+               Do_Not_Instrument := True;
                Report (UIC, N,
                        "gnatcov limitation:"
                        & " cannot instrument generic null procedures."
@@ -4036,7 +4007,7 @@ package body Instrument.Ada_Unit is
                --  so that the augmented EF is no longer a primitive of its
                --  return type. Need to check for potential freezing issues.
 
-               Unsupported := True;
+               Do_Not_Instrument := True;
                Report (UIC, N,
                        "gnatcov limitation:"
                        & " cannot instrument an expression function which is"
@@ -4047,7 +4018,7 @@ package body Instrument.Ada_Unit is
             elsif Is_Self_Referencing (UIC, N.As_Expr_Function)
                  and then not Common_Nodes.Ctrl_Type.Is_Null
             then
-               Unsupported := True;
+               Do_Not_Instrument := True;
                Report (UIC, N,
                        "gnatcov limitation:"
                        & " instrumenting a self referencing (i.e. recursive)"
@@ -4086,11 +4057,10 @@ package body Instrument.Ada_Unit is
 
             New_Insertion_Info :=
               (Method         => Expression_Function,
-               Unsupported    => Unsupported,
                Witness_Actual => No_Node_Rewriting_Handle,
                Witness_Formal => No_Node_Rewriting_Handle);
 
-            if not New_Insertion_Info.Unsupported then
+            if not Do_Not_Instrument then
 
                --  Pass all expression function parameters to the augmented
                --  expression function call.
@@ -4124,7 +4094,6 @@ package body Instrument.Ada_Unit is
 
             New_Insertion_Info :=
               (Method                => Statement,
-               Unsupported           => Unsupported,
                RH_List               => NP_Nodes.Stmt_List,
                Index                 => 1,
                Rewriting_Offset      => 0,
@@ -4153,29 +4122,21 @@ package body Instrument.Ada_Unit is
             declare
                N_Expr : constant Expr := N.As_Expr_Function.F_Expr;
             begin
-               Extend_Statement_Sequence (UIC, N_Expr, 'X');
-
-               --  For unsupported expression functions, creating a statement
-               --  obligation is enough: it will never be satisfied and thus
-               --  violations regarding conditions/decisions will not be
-               --  displayed, so no need to bother creating them and adding
-               --  special cases in decision processings for unsupported
-               --  expression functions.
-
-               if not New_Insertion_Info.Unsupported then
-                  Process_Decisions_Defer (N_Expr, 'X');
-               end if;
+               Extend_Statement_Sequence
+                 (UIC, N_Expr, 'X', Do_Not_Instrument => Do_Not_Instrument);
+               Process_Decisions_Defer (N_Expr, 'X', Do_Not_Instrument);
             end;
          else
             --  Even though there is a "null" keyword in the null procedure,
             --  is no dedicated node for it in the Libadalang parse tree: use
             --  the whole null procedure declaration to provide a sloc.
 
             Extend_Statement_Sequence
-              (UIC         => UIC,
-               N           => N,
-               Typ         => 'X',
-               Insertion_N => NP_Nodes.Null_Stmt);
+              (UIC               => UIC,
+               N                 => N,
+               Typ               => 'X',
+               Insertion_N       => NP_Nodes.Null_Stmt,
+               Do_Not_Instrument => Do_Not_Instrument);
          end if;
          Set_Statement_Entry;
 
@@ -4187,7 +4148,7 @@ package body Instrument.Ada_Unit is
          --  There is nothing else to do if we gave up instrumenting this
          --  subprogram.
 
-         if New_Insertion_Info.Unsupported then
+         if Do_Not_Instrument then
             return;
          end if;
 
@@ -5171,7 +5132,6 @@ package body Instrument.Ada_Unit is
                else Declaration);
             II : Insertion_Info (Method);
          begin
-            II.Unsupported := False;
             II.RH_List := Handle (L);
             II.Index := 0;
             II.Rewriting_Offset := 0;
@@ -5686,7 +5646,6 @@ package body Instrument.Ada_Unit is
          Op_NK : Ada_Node_Kind_Type;
 
       begin
-
          --  Logical operator
 
          if Is_Logical_Operator (UIC, N) then
@@ -5733,14 +5692,16 @@ package body Instrument.Ada_Unit is
          else
             Output_Element (N.As_Ada_Node);
 
+            if Decision_Static or else Do_Not_Instrument then
+               return;
+            end if;
             if MCDC_Coverage_Enabled then
                UIC.Source_Conditions.Append
                  (Source_Condition'
                     (LL_SCO          => SCOs.SCO_Table.Last,
                      Condition       => N.As_Expr,
                      State           => MCDC_State,
-                     First           => Condition_Count = 0,
-                     Decision_Static => Decision_Static));
+                     First           => Condition_Count = 0));
 
                Condition_Count := Condition_Count + 1;
             end if;
@@ -5778,6 +5739,9 @@ package body Instrument.Ada_Unit is
             SFI  => UIC.SFI,
             Last => False);
          Hash_Entries.Append ((Start_Sloc (N_SR), SCOs.SCO_Table.Last));
+         if Do_Not_Instrument then
+            UIC.Non_Instr_LL_SCOs.Include (SCO_Id (SCOs.SCO_Table.Last));
+         end if;
       end Output_Element;
 
       -------------------
@@ -5858,6 +5822,9 @@ package body Instrument.Ada_Unit is
             SFI                => UIC.SFI,
             Last               => False,
             Pragma_Aspect_Name => Nam);
+         if Do_Not_Instrument then
+            UIC.Non_Instr_LL_SCOs.Include (SCO_Id (SCOs.SCO_Table.Last));
+         end if;
 
          Current_Decision := SCOs.SCO_Table.Last;
 
@@ -5896,13 +5863,15 @@ package body Instrument.Ada_Unit is
             --  For this reason, also refrain from instrumenting static
             --  decisions.
 
-            UIC.Source_Decisions.Append
-              (Source_Decision'
-                 (LL_SCO            => Current_Decision,
-                  Decision          => N.As_Expr,
-                  State             => MCDC_State,
-                  Do_Not_Instrument => Do_Not_Instrument
-                                       or else Is_Static_Expr (N.As_Expr)));
+            if not (Do_Not_Instrument
+                    or else Is_Static_Expr (N.As_Expr))
+            then
+               UIC.Source_Decisions.Append
+                 (Source_Decision'
+                    (LL_SCO   => Current_Decision,
+                     Decision => N.As_Expr,
+                     State    => MCDC_State));
+            end if;
          end if;
 
          --  For an aspect specification, which will be rewritten into a
@@ -8224,18 +8193,10 @@ package body Instrument.Ada_Unit is
 
          if Coverage.Enabled (Decision) or else MCDC_Coverage_Enabled then
             for SD of UIC.Source_Decisions loop
-
-               --  Mark non-instrumented decisions as such so that they are
-               --  properly reported.
-
                declare
                   HL_SCO : constant SCO_Id := SCO_Map (SD.LL_SCO);
                begin
-                  if SD.Do_Not_Instrument then
-                     Set_Decision_SCO_Non_Instr (HL_SCO);
-                  else
-                     Insert_Decision_Witness (UIC, SD, Path_Count (HL_SCO));
-                  end if;
+                  Insert_Decision_Witness (UIC, SD, Path_Count (HL_SCO));
                end;
             end loop;
 
@@ -8249,11 +8210,6 @@ package body Instrument.Ada_Unit is
                --  in a decision with a path count exceeding the limit to avoid
                --  generating overly large traces / run out of memory.
                --
-               --  We also do not include witness calls for conditions of
-               --  static decision, as this would make the instrumented
-               --  expression non-static. Mark the enclosing decision as not
-               --  instrumented for MCDC instead.
-               --
                --  As we go through each condition, mark their enclosing
                --  decision as not instrumented if their number of paths
                --  exceeds our limit.
@@ -8267,9 +8223,7 @@ package body Instrument.Ada_Unit is
                      --  If the number of paths in the decision binary diagram
                      --  exceeds the path count limit, we do not instrument it.
 
-                     if Path_Count (Decision) > Get_Path_Count_Limit
-                       and then not SC.Decision_Static
-                     then
+                     if Path_Count (Decision) > Get_Path_Count_Limit then
                         Set_Decision_SCO_Non_Instr_For_MCDC (Decision);
                      else
                         Insert_Condition_Witness