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* Refactor of is_cyclic to use a linked list on the stack instead of a dynamic array

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J. Gareth "Curious Kit" Moreton 2022-12-04 20:32:45 +00:00 committed by FPK
parent 4b659175d9
commit a1abe51f2a
1 changed files with 40 additions and 34 deletions
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74
compiler/defutil.pas
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@ -230,7 +230,7 @@ interface
function is_voidpointer(p : tdef) : boolean; function is_voidpointer(p : tdef) : boolean;
{# Returns true if p is a cyclic reference (refers to itself at some point via pointer or array) } {# Returns true if p is a cyclic reference (refers to itself at some point via pointer or array) }
function is_cyclic(p : tdef): Boolean; function is_cyclic(p : tdef): Boolean; {$ifdef USEINLINE}inline;{$endif USEINLINE}
{# Returns true, if definition is a float } {# Returns true, if definition is a float }
function is_fpu(def : tdef) : boolean; function is_fpu(def : tdef) : boolean;
@ -1033,41 +1033,47 @@ implementation
end; end;
{ true, if p is a cyclic reference (refers to itself at some point via pointer or array) } type
function is_cyclic(p : tdef): Boolean; PDefListItem = ^TDefListItem;
TDefListItem = record
Next: PDefListItem;
Def: tdef;
end;
{ See "is_cyclic" below }
function is_cyclic_internal(const def: tdef; const first: PDefListItem): Boolean;
var var
DefList: array of TDef; thisdef: TDefListItem;
CurrentTop: Integer; curitem: PDefListItem;
function is_cyclic_internal(def: tdef): Boolean;
var
X: Integer;
begin
if not (def.typ in [arraydef, pointerdef]) then
Exit(False);
CurrentTop := Length(DefList);
{ Check to see if the definition has appeared already }
for X := 0 to CurrentTop - 1 do
if def = DefList[X] then
Exit(True);
SetLength(DefList, CurrentTop + 1);
DefList[CurrentTop] := def;
case def.typ of
arraydef:
Result := is_cyclic_internal(tarraydef(def).elementdef);
pointerdef:
Result := is_cyclic_internal(tabstractpointerdef(def).pointeddef);
else
InternalError(2022120301);
end;
end;
begin begin
Result := is_cyclic_internal(p); if not (def.typ in [arraydef, pointerdef]) then
Exit(False);
curitem := first;
while assigned(curitem) do
begin
if curitem^.Def = def then
Exit(True);
curitem := curitem^.Next;
end;
thisdef.Next := first;
thisdef.Def := def;
case def.typ of
arraydef:
Result := is_cyclic_internal(tarraydef(def).elementdef, @thisdef);
pointerdef:
Result := is_cyclic_internal(tabstractpointerdef(def).pointeddef, @thisdef);
else
InternalError(2022120301);
end;
end;
{ true, if p is a cyclic reference (refers to itself at some point via pointer or array) }
function is_cyclic(p : tdef): Boolean; {$ifdef USEINLINE}inline;{$endif USEINLINE}
begin
Result := is_cyclic_internal(p, nil);
end; end;
{ true, if def is a 8 bit int type } { true, if def is a 8 bit int type }