FPDebug: refactor

git-svn-id: trunk@43392 -

components/fpdebug/fpdbgdwarf.pas

@@ -811,6 +811,17 @@ DECL = DW_AT_decl_column, DW_AT_decl_file, DW_AT_decl_line
     destructor Destroy; override;
   end;
 
+  { TDbgDwarfUnit }
+
+  TDbgDwarfUnit = class(TDbgDwarfIdentifier)
+  private
+    FLastChildByName: TDbgSymbol;
+  protected
+    procedure Init; override;
+    function GetMemberByName(AIndex: String): TDbgSymbol; override;
+  public
+    destructor Destroy; override;
+  end;
 
 type
   TDwarfSection = (dsAbbrev, dsARanges, dsFrame,  dsInfo, dsLine, dsLoc, dsMacinfo, dsPubNames, dsPubTypes, dsRanges, dsStr);
@@ -833,6 +844,7 @@ const
   { TDbgDwarf }
 
 type
+
   TDbgDwarf = class(TDbgInfo)
   private
     FCompilationUnits: TList;
@@ -842,12 +854,13 @@ type
   protected
     function GetCompilationUnitClass: TDwarfCompilationUnitClass; virtual;
     function FindCompilationUnitByOffs(AOffs: QWord): TDwarfCompilationUnit;
+    function FindProcSymbol(AAddress: TDbgPtr): TDbgSymbol;
   public
     constructor Create(ALoader: TDbgImageLoader); override;
     destructor Destroy; override;
+    function FindContext(AAddress: TDbgPtr): TDbgInfoAddressContext; override;
     function FindSymbol(AAddress: TDbgPtr): TDbgSymbol; override;
     //function FindSymbol(const AName: String): TDbgSymbol; override;
-    function FindIdentifier(AAddress: TDbgPtr; AName: String): TDbgSymbol;
     function GetLineAddress(const AFileName: String; ALine: Cardinal): TDbgPtr; override;
     function GetLineAddressMap(const AFileName: String): PDWarfLineMap;
     function LoadCompilationUnits: Integer;
@@ -865,6 +878,22 @@ type
   public
   end;
   
+  { TDbgDwarfInfoAddressContext }
+
+  TDbgDwarfInfoAddressContext = class(TDbgInfoAddressContext)
+  private
+    FSymbol: TDbgSymbol;
+    FAddress: TDbgPtr;
+    FDwarf: TDbgDwarf;
+  protected
+    function GetSymbolAtAddress: TDbgSymbol; override;
+    function GetAddress: TDbgPtr; override;
+  public
+    constructor Create(AnAddress: TDbgPtr; ASymbol: TDbgSymbol; ADwarf: TDbgDwarf);
+    destructor Destroy; override;
+    function FindSymbol(const AName: String): TDbgSymbol; override;
+  end;
+
 
 function DwarfTagToString(AValue: Integer): String;
 function DwarfAttributeToString(AValue: Integer): String;
@@ -1331,6 +1360,119 @@ begin
   end;
 end;
 
+{ TDbgDwarfInfoAddressContext }
+
+function TDbgDwarfInfoAddressContext.GetSymbolAtAddress: TDbgSymbol;
+begin
+  Result := FSymbol;
+end;
+
+function TDbgDwarfInfoAddressContext.GetAddress: TDbgPtr;
+begin
+  Result := FAddress;
+end;
+
+constructor TDbgDwarfInfoAddressContext.Create(AnAddress: TDbgPtr; ASymbol: TDbgSymbol;
+  ADwarf: TDbgDwarf);
+begin
+  inherited Create;
+  AddReference;
+  FAddress := AnAddress;
+  FDwarf   := ADwarf;
+  FSymbol  := ASymbol;
+  FSymbol.AddReference;
+end;
+
+destructor TDbgDwarfInfoAddressContext.Destroy;
+begin
+  FSymbol.ReleaseReference;
+  inherited Destroy;
+end;
+
+function TDbgDwarfInfoAddressContext.FindSymbol(const AName: String): TDbgSymbol;
+var
+  SubRoutine: TDbgDwarfProcSymbol; // TDbgSymbol;
+  CU: TDwarfCompilationUnit;
+  //Scope,
+  StartScopeIdx: Integer;
+  InfoEntry: TDwarfInformationEntry;
+  s, InfoName: String;
+begin
+  Result := nil;
+  if (FSymbol = nil) or not(FSymbol is TDbgDwarfProcSymbol) then
+    exit;
+
+  SubRoutine := TDbgDwarfProcSymbol(FSymbol);
+  s := UpperCase(AName);
+
+  try
+    CU := SubRoutine.FCU;
+    InfoEntry := SubRoutine.InformationEntry.Clone;
+    //InfoEntry := TDwarfInformationEntry.Create(CU, nil);
+    //InfoEntry.ScopeIndex := SubRoutine.FAddressInfo^.ScopeIndex;
+
+    while InfoEntry.HasValidScope do begin
+      debugln(FPDBG_DWARF_SEARCH, ['TDbgDwarf.FindIdentifier Searching ', dbgs(InfoEntry.FScope, CU)]);
+      StartScopeIdx := InfoEntry.ScopeIndex;
+
+      if InfoEntry.ReadValue(DW_AT_name, InfoName) then begin
+        if UpperCase(InfoName) = s then begin
+          Result := TDbgDwarfIdentifier.CreateSubClass(AName, InfoEntry);
+          DebugLn(FPDBG_DWARF_SEARCH, ['TDbgDwarf.FindIdentifier found ', dbgs(InfoEntry.FScope, CU), DbgSName(Result)]);
+          break;
+        end;
+      end;
+
+      if InfoEntry.GoNamedChildEx(AName) then begin
+        Result := TDbgDwarfIdentifier.CreateSubClass(AName, InfoEntry);
+        DebugLn(FPDBG_DWARF_SEARCH, ['TDbgDwarf.FindIdentifier found ', dbgs(InfoEntry.FScope, CU), DbgSName(Result)]);
+        break;
+      end;
+
+      // Search parent(s)
+      InfoEntry.ScopeIndex := StartScopeIdx;
+      InfoEntry.GoParent;
+    end;
+
+  // other units
+
+  finally
+    ReleaseRefAndNil(InfoEntry);
+  end;
+end;
+
+{ TDbgDwarfUnit }
+
+procedure TDbgDwarfUnit.Init;
+begin
+  inherited Init;
+  SetSymbolType(stNone);
+  SetKind(skUnit);
+end;
+
+function TDbgDwarfUnit.GetMemberByName(AIndex: String): TDbgSymbol;
+var
+  Ident: TDwarfInformationEntry;
+  ti: TDbgSymbol;
+begin
+  // Todo, param to only search external.
+  ReleaseRefAndNil(FLastChildByName);
+  Result := nil;
+
+  Ident := FInformationEntry.Clone;
+  Ident.GoNamedChildEx(AIndex);
+  if Ident <> nil then
+    Result := TDbgDwarfIdentifier.CreateSubClass('', Ident);
+  ReleaseRefAndNil(Ident);
+  FLastChildByName := Result;
+end;
+
+destructor TDbgDwarfUnit.Destroy;
+begin
+  ReleaseRefAndNil(FLastChildByName);
+  inherited Destroy;
+end;
+
 { TDbgDwarfIdentifierSubRange }
 
 procedure TDbgDwarfIdentifierSubRange.ReadBounds;
@@ -2577,6 +2719,8 @@ begin
     // Value types
     DW_TAG_member:           Result := TDbgDwarfIdentifierMember;
     DW_TAG_subprogram:       Result := TDbgDwarfProcSymbol;
+    //
+    DW_TAG_compile_unit:     Result := TDbgDwarfUnit;
 
     else
       Result := TDbgDwarfIdentifier;
@@ -3571,110 +3715,22 @@ begin
   inherited Destroy;
 end;
 
-function TDbgDwarf.FindSymbol(AAddress: TDbgPtr): TDbgSymbol;
+function TDbgDwarf.FindContext(AAddress: TDbgPtr): TDbgInfoAddressContext;
 var
-  n: Integer;
+  Proc: TDbgSymbol;
-  CU: TDwarfCompilationUnit;
-  Iter: TMapIterator;
-  Info: PDwarfAddressInfo;
-  MinMaxSet: boolean;
 begin
   Result := nil;
-  for n := 0 to FCompilationUnits.Count - 1 do
+  Proc := FindProcSymbol(AAddress);
-  begin
+  if Proc = nil then
-    CU := TDwarfCompilationUnit(FCompilationUnits[n]);
-    if not CU.Valid then Continue;
-    MinMaxSet := CU.FMinPC <> CU.FMaxPC;
-    if MinMaxSet and ((AAddress < CU.FMinPC) or (AAddress > CU.FMaxPC))
-    then Continue;
-    
-    CU.BuildAddressMap;
-
-    Iter := TMapIterator.Create(CU.FAddressMap);
-    try
-      if Iter.EOM
-      then begin
-        if MinMaxSet
-        then Exit //  minmaxset and no procs defined ???
-        else Continue;
-      end;
-
-      if not Iter.Locate(AAddress)
-      then begin
-        if not Iter.BOM
-        then Iter.Previous;
-
-        if Iter.BOM
-        then begin
-          if MinMaxSet
-          then Exit //  minmaxset and no proc @ minpc ???
-          else Continue;
-        end;
-      end;
-      
-      // iter is at the closest defined adress before AAddress
-      Info := Iter.DataPtr;
-      if AAddress > Info^.EndPC
-      then begin
-        if MinMaxSet
-        then Exit //  minmaxset and no proc @ maxpc ???
-        else Continue;
-      end;
-      
-      Result := TDbgDwarfProcSymbol.Create(CU, Iter.DataPtr, AAddress);
-    finally
-      Iter.Free;
-    end;
-  end;
-end;
-
-function TDbgDwarf.FindIdentifier(AAddress: TDbgPtr; AName: String): TDbgSymbol;
-var
-  SubRoutine: TDbgDwarfProcSymbol; // TDbgSymbol;
-  CU: TDwarfCompilationUnit;
-  //Scope,
-  StartScopeIdx: Integer;
-  InfoEntry: TDwarfInformationEntry;
-begin
-  Result := nil;
-  SubRoutine := TDbgDwarfProcSymbol(FindSymbol(AAddress));
-  if SubRoutine = nil then
     exit;
 
-  try
+  Result := TDbgDwarfInfoAddressContext.Create(AAddress, Proc, Self);
-    CU := SubRoutine.FCU;
+  Proc.ReleaseReference;
-    InfoEntry := TDwarfInformationEntry.Create(CU, nil);
+end;
-    InfoEntry.ScopeIndex := SubRoutine.FAddressInfo^.ScopeIndex;
 
-    while InfoEntry.HasValidScope do begin
+function TDbgDwarf.FindSymbol(AAddress: TDbgPtr): TDbgSymbol;
-      debugln(FPDBG_DWARF_SEARCH, ['TDbgDwarf.FindIdentifier Searching ', dbgs(InfoEntry.FScope, CU)]);
+begin
-      StartScopeIdx := InfoEntry.ScopeIndex;
+  Result := FindProcSymbol(AAddress);
-
-      if InfoEntry.GoNamedChildEx(AName) then begin
-        Result := TDbgDwarfIdentifier.CreateSubClass(AName, InfoEntry);
-        DebugLn(FPDBG_DWARF_SEARCH, ['TDbgDwarf.FindIdentifier found ', dbgs(InfoEntry.FScope, CU), DbgSName(Result)]);
-        break;
-      end;
-
-      // Search parent(s)
-      InfoEntry.ScopeIndex := StartScopeIdx;
-      InfoEntry.GoParent;
-    end;
-
-  // unitname?
-
-//// debugln:
-//    if Result <> nil then begin
-//      TDbgDwarfIdentifier(Result).TypeInfo; // debugln...
-//      if TDbgDwarfIdentifier(Result).TypeInfo <> nil then TDbgDwarfIdentifier(Result).TypeInfo.TypeInfo;
-//    end;
-//// end debugln
-
-
-  finally
-    ReleaseRefAndNil(SubRoutine);
-    ReleaseRefAndNil(InfoEntry);
-  end;
 end;
 
 function TDbgDwarf.GetCompilationUnit(AIndex: Integer): TDwarfCompilationUnit;
@@ -3708,6 +3764,63 @@ begin
     Result := nil;
 end;
 
+function TDbgDwarf.FindProcSymbol(AAddress: TDbgPtr): TDbgSymbol;
+var
+  n: Integer;
+  CU: TDwarfCompilationUnit;
+  Iter: TMapIterator;
+  Info: PDwarfAddressInfo;
+  MinMaxSet: boolean;
+begin
+  Result := nil;
+  for n := 0 to FCompilationUnits.Count - 1 do
+  begin
+    CU := TDwarfCompilationUnit(FCompilationUnits[n]);
+    if not CU.Valid then Continue;
+    MinMaxSet := CU.FMinPC <> CU.FMaxPC;
+    if MinMaxSet and ((AAddress < CU.FMinPC) or (AAddress > CU.FMaxPC))
+    then Continue;
+
+    CU.BuildAddressMap;
+
+    Iter := TMapIterator.Create(CU.FAddressMap);
+    try
+      if Iter.EOM
+      then begin
+        if MinMaxSet
+        then Exit //  minmaxset and no procs defined ???
+        else Continue;
+      end;
+
+      if not Iter.Locate(AAddress)
+      then begin
+        if not Iter.BOM
+        then Iter.Previous;
+
+        if Iter.BOM
+        then begin
+          if MinMaxSet
+          then Exit //  minmaxset and no proc @ minpc ???
+          else Continue;
+        end;
+      end;
+
+      // iter is at the closest defined adress before AAddress
+      Info := Iter.DataPtr;
+      if AAddress > Info^.EndPC
+      then begin
+        if MinMaxSet
+        then Exit //  minmaxset and no proc @ maxpc ???
+        else Continue;
+      end;
+
+      Result := TDbgDwarfProcSymbol.Create(CU, Iter.DataPtr, AAddress);
+    finally
+      Iter.Free;
+    end;
+  end;
+end;
+
 function TDbgDwarf.GetLineAddress(const AFileName: String; ALine: Cardinal): TDbgPtr;
 var
   n: Integer;

components/fpdebug/fpdbginfo.pas

@@ -209,6 +209,19 @@ type
     function GetMemberCount: Integer; override;
   end;
 
+  { TDbgInfoAddressContext }
+
+  TDbgInfoAddressContext = class(TRefCountedObject)
+  protected
+    function GetAddress: TDbgPtr; virtual; abstract;
+    function GetSymbolAtAddress: TDbgSymbol; virtual;
+  public
+    property Address: TDbgPtr read GetAddress;
+    property SymbolAtAddress: TDbgSymbol read GetSymbolAtAddress;
+    // search this, and all parent context
+    function FindSymbol(const AName: String): TDbgSymbol; virtual;
+  end;
+
   { TDbgInfo }
 
   TDbgInfo = class(TObject)
@@ -218,8 +231,9 @@ type
     procedure SetHasInfo;
   public
     constructor Create({%H-}ALoader: TDbgImageLoader); virtual;
-    function FindSymbol(const {%H-}AName: String): TDbgSymbol; virtual;
+    function FindContext({%H-}AAddress: TDbgPtr): TDbgInfoAddressContext; virtual;
-    function FindSymbol({%H-}AAddress: TDbgPtr): TDbgSymbol; virtual;
+    function FindSymbol(const {%H-}AName: String): TDbgSymbol; virtual; deprecated;
+    function FindSymbol({%H-}AAddress: TDbgPtr): TDbgSymbol; virtual; deprecated;
     property HasInfo: Boolean read FHasInfo;
     function GetLineAddress(const {%H-}AFileName: String; {%H-}ALine: Cardinal): TDbgPtr; virtual;
   end;
@@ -234,6 +248,18 @@ begin
   WriteStr(Result, ADbgSymbolKind);
 end;
 
+{ TDbgInfoAddressContext }
+
+function TDbgInfoAddressContext.GetSymbolAtAddress: TDbgSymbol;
+begin
+  Result := nil;
+end;
+
+function TDbgInfoAddressContext.FindSymbol(const AName: String): TDbgSymbol;
+begin
+  Result := nil;
+end;
+
 { TDbgSymbol }
 
 constructor TDbgSymbol.Create(const AName: String);
@@ -661,6 +687,11 @@ begin
   inherited Create;
 end;
 
+function TDbgInfo.FindContext(AAddress: TDbgPtr): TDbgInfoAddressContext;
+begin
+  Result := nil;
+end;
+
 function TDbgInfo.FindSymbol(const AName: String): TDbgSymbol;
 begin
   Result := nil;

components/fpdebug/test/testpascalparser.pas

@@ -392,6 +392,15 @@ begin
     TestExpr([0,0,1],   TFpPascalExpressionPartIdentifer, 'a', 0);
     TestExpr([0,1],   TFpPascalExpressionPartIdentifer, 'b', 0);
 
+    CreateExpr('f[a]', True);
+    TestExpr([], TFpPascalExpressionPartBracketIndex, '[', 2);
+    TestExpr([0],   TFpPascalExpressionPartIdentifer, 'f', 0);
+    TestExpr([1],   TFpPascalExpressionPartIdentifer, 'a', 0);
+
+    CreateExpr('TFoo(f^[0]).a', True);
+
+    CreateExpr('^^int(1)', True);
+
   finally
     CurrentTestExprObj.Free;
   end;

components/fpdebug/test/testtypeinfo.pas

@@ -44,10 +44,14 @@ var
 function TTestPascalExpression.GetDbgTyeForIdentifier(AnIdent: String): TDbgSymbol;
 var
   Loc: TDBGPtr;
+  Ctx: TDbgInfoAddressContext;
 begin
   Result := nil;
-  if (FDwarfInfo <> nil) and (AnIdent <> '') then
+  if (FDwarfInfo <> nil) and (AnIdent <> '') then begin
-    Result := FDwarfInfo.FindIdentifier(Location, AnIdent);
+    Ctx := FDwarfInfo.FindContext(Location);
+    Result := Ctx.FindSymbol(AnIdent);
+    Ctx.ReleaseReference;
+  end;
 end;
 
 procedure TTestTypInfo.LoadDwarf(AFileName: String);
@@ -261,6 +265,8 @@ GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
     DoTest('testc2.a5', skArray);
     AssertTrue(TestText + ' Flag: ', sfStatArray in Expr.ResultType.Flags);
 GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+GetTypeAsDeclaration(s, Expr.ResultType, [tdfSkipClassBody, tdfSkipRecordBody]); DebugLn(s);
+
 
     DoTest('testc2.a6', skArray);
     AssertTrue(TestText + ' Flag: ', sfDynArray in Expr.ResultType.Flags);
@@ -272,6 +278,37 @@ GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
 
 
 
+    DoTest('a1[1]', skBoolean);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+    DoTest('a1[3]', skBoolean);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+
+    DoTest('a1b[1]', skArray);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+    DoTest('a1b[3]', skArray);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+
+    DoTest('a1b[1][3]', skBoolean);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+    DoTest('a1b[3][4]', skBoolean);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+
+    DoTest('TTestClass(0)', skClass);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+    DoTest('TTestClass(0).FWord', skCardinal);
+GetTypeAsDeclaration(s, Expr.ResultType); DebugLn(s);
+
+
+    DoTest('TTestClass2(0).enum4', skPointer);
+    DoTest('TTestClass2(0).enum4^', skEnum);
+
     FreeAndNil(expr);
   end;
 
@@ -292,5 +329,6 @@ end;
 initialization
 
   RegisterTest(TTestTypInfo);
+  DebugLogger.FindOrRegisterLogGroup('FPDBG_DWARF_SEARCH' {$IFDEF FPDBG_DWARF_SEARCH} , True {$ENDIF} )^.Enabled := True;
 end.
 

debugger/fpgdbmidebugger.pp

@@ -38,12 +38,19 @@ type
     property Debugger: TFpGDBMIDebugger read FDebugger;
   end;
 
+const
+  MAX_CTX_CACHE = 10;
+
+type
   { TFpGDBMIDebugger }
 
   TFpGDBMIDebugger = class(TGDBMIDebugger)
   private
     FImageLoader: TDbgImageLoader;
     FDwarfInfo: TDbgDwarf;
+    // cache last context
+    FlastStackFrame, FLastThread: Integer;
+    FLastContext: array [0..MAX_CTX_CACHE-1] of TDbgInfoAddressContext;
   protected
     function CreateCommandStartDebugging(AContinueCommand: TGDBMIDebuggerCommand): TGDBMIDebuggerCommandStartDebugging; override;
     function CreateLineInfo: TDBGLineInfo; override;
@@ -56,6 +63,7 @@ type
 
     procedure GetCurrentContext(out AThreadId, AStackFrame: Integer);
     function  GetLocationForContext(AThreadId, AStackFrame: Integer): TDBGPtr;
+    function  GetInfoContextForContext(AThreadId, AStackFrame: Integer): TDbgInfoAddressContext;
     function CreateTypeRequestCache: TGDBPTypeRequestCache; override;
   public
     class function Caption: String; override;
@@ -113,13 +121,19 @@ type
 function TFpGDBMIPascalExpression.GetDbgTyeForIdentifier(AnIdent: String): TDbgSymbol;
 var
   Loc: TDBGPtr;
+  Ctx: TDbgInfoAddressContext;
 begin
   Result := nil;
   if FDebugger.HasDwarf then begin
     if AnIdent <> '' then begin
-      Loc := FDebugger.GetLocationForContext(FThreadId, FStackFrame);
+      //Loc := FDebugger.GetLocationForContext(FThreadId, FStackFrame);
-      if (Loc <> 0) then
+      //if (Loc <> 0) then begin
-        Result := FDebugger.FDwarfInfo.FindIdentifier(Loc, AnIdent);
+        Ctx := FDebugger.GetInfoContextForContext(FThreadId, FStackFrame);
+        //Ctx := FDebugger.FDwarfInfo.FindContext(Loc);
+      if Ctx <> nil then
+        Result := Ctx.FindSymbol(AnIdent);
+        //Ctx.ReleaseReference;
+      //end;
     end;
   end;
 end;
@@ -439,7 +453,7 @@ const
     ASrcTypeName, ADeRefTypeName, ABaseTypeName: String;
     ASrcType, ABaseType: TDbgSymbol);
   var
-    s, s2: String;
+    s: String;
     ElemPointerLevel: Integer;
     ElemDeRefType, ElemBaseType: TDbgSymbol;
     ElemSrcTypeName, ElemDeRefTypeName, ElemBaseTypeName: String;
@@ -724,10 +738,16 @@ end;
 { TFpGDBMIDebugger }
 
 procedure TFpGDBMIDebugger.DoState(const OldState: TDBGState);
+var
+  i: Integer;
 begin
   inherited DoState(OldState);
   if State in [dsStop, dsError, dsNone] then
     UnLoadDwarf;
+
+  if OldState in [dsPause, dsInternalPause] then
+    for i := 0 to MAX_CTX_CACHE-1 do
+      ReleaseRefAndNil(FLastContext[i]);
 end;
 
 function TFpGDBMIDebugger.HasDwarf: Boolean;
@@ -830,6 +850,40 @@ begin
 
 end;
 
+function TFpGDBMIDebugger.GetInfoContextForContext(AThreadId,
+  AStackFrame: Integer): TDbgInfoAddressContext;
+var
+  Addr: TDBGPtr;
+begin
+  if (AThreadId <= 0) then begin
+    GetCurrentContext(AThreadId, AStackFrame);
+  end;
+
+  Addr := GetLocationForContext(AThreadId, AStackFrame);
+
+  if Addr = 0 then begin
+    Result := nil;
+    exit;
+  end;
+
+  if (AStackFrame >= FlastStackFrame) and
+     (AStackFrame - FlastStackFrame < MAX_CTX_CACHE) and
+     (FLastContext[AStackFrame - FlastStackFrame] <> nil) and
+     (FLastContext[AStackFrame - FlastStackFrame].Address = Addr)
+  then begin
+DebugLn('cached contex');
+    Result := FLastContext[AStackFrame - FlastStackFrame];
+    exit;
+  end;
+
+  Result := FDwarfInfo.FindContext(Addr);
+
+  FLastThread := AThreadId;
+  FlastStackFrame := AStackFrame;
+  FLastContext[0].ReleaseReference;
+  FLastContext[0] := Result;
+end;
+
 type
   TGDBMIDwarfTypeIdentifier = class(TDbgDwarfTypeIdentifier)
   public