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[modula2] Variable analysis understands DISPOSE and NIL

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This patch allows the uninitialized variable analysis to detect pointer
through NIL and incorrectly reusing a pointer after a call to DISPOSE.

gcc/m2/ChangeLog:

	* gm2-compiler/M2Quads.mod (BuildRealFuncProcCall): Set the trash
	parameter value to NIL if DEALLOCATE is detected.
	* gm2-compiler/M2SymInit.mod (CheckDeferredRecordAccess): Pass
	tok to SetVarInitialized.  Pass tok to GetVarComponentInitialized.
	(ComponentFindVar): Add tok parameter.  Check aliased pointer
	against Nil and generate warning if necessary.
	(deRefComponent): Add tok and sym parameters and pass them to
	getContent.
	(SetVarComponentInitialized): Add tok parameter.  Pass tok to
	ComponentFindVar.  Pass tok and sym to deRefComponent.
	(GetVarComponentInitialized): Add tok parameter.  Pass tok to
	ComponentFindVar.  Pass tok to deRefComponent.
	(SetVarInitialized): Add tok parameter.  Pass tok to
	SetVarComponentInitialized.
	(doGetVarInitialized): Add tok parameter.  Pass tok to
	GetVarComponentInitialized.
	(CheckXIndr): Pass lhs and lhstok to getContent.
	(CheckIndrX): Pass rhs and rhstok to getContent.
	(CheckBecomes): Pass destok to ComponentFindVar.  Pass des and
	destok to deRefComponent.
	(CheckAddr): Pass contenttok to GetVarInitialized.  Pass ptrtok
	to SetVarInitialized.
	(CheckReadBeforeInitQuad): Pass op1tok to SetVarInitialized for
	op1 cases and op3tok for op3 cases.
	(trashParam): Get operand tokens.  Pass op3tok to
	SetVarInitialized.  Pass op3 and op3tok to getContent.
	Alias ptr to NIL if procedure is DEALLOCATE.  Pass op3tok to
	SetVarInitialized.
	(IsDeallocate): New procedure function.
	(DetectTrash): Use IsDeallocate.
	(SetupLAlias): Allow exp to be Nil.
	(getContent): Generate warning message if ptr is Nil.

gcc/testsuite/ChangeLog:

	* gm2/switches/uninit-variable-checking/procedures/fail/testdispose.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testdispose2.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnil.mod: New test.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>
This commit is contained in:
Gaius Mulley 2023-07-19 13:38:07 +01:00
parent fcb3819642
commit e029635cb7
5 changed files with 163 additions and 59 deletions
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12
gcc/m2/gm2-compiler/M2Quads.mod
View file

@ -5269,9 +5269,15 @@ BEGIN
THEN
GenQuadO (paramtok, ParamOp, i, Proc, OperandT (pi), TRUE)
ELSE
trash := MakeTemporary (paramtok, RightValue) ;
PutVar (trash, ParamType) ;
PutVarHeap (trash, TRUE) ;
IF AllocateProc
THEN
trash := MakeTemporary (paramtok, RightValue) ;
PutVar (trash, ParamType) ;
PutVarHeap (trash, TRUE)
ELSE
Assert (DeallocateProc) ;
trash := Nil
END ;
GenQuadOTrash (paramtok, ParamOp, i, Proc, OperandT (pi), TRUE, trash)
END
ELSE

145
gcc/m2/gm2-compiler/M2SymInit.mod
View file

@ -26,6 +26,7 @@ FROM M2Debug IMPORT Assert ;
FROM M2Printf IMPORT printf0, printf1, printf2, printf3, printf4 ;
FROM libc IMPORT printf ;
FROM NameKey IMPORT Name, NulName, KeyToCharStar, MakeKey ;
FROM M2Base IMPORT Nil ;
FROM M2Options IMPORT UninitVariableChecking, UninitVariableConditionalChecking,
CompilerDebugging ;
@ -693,11 +694,11 @@ BEGIN
(* SetVarInitialized (sym, TRUE) *)
ELSIF IsUnbounded (GetSType (sym))
THEN
SetVarInitialized (sym, TRUE)
SetVarInitialized (sym, TRUE, tok)
ELSIF IsComponent (sym)
THEN
Trace ("checkReadInit IsComponent (%d) is true)", sym) ;
IF (NOT GetVarComponentInitialized (sym)) AND IsUniqueWarning (tok)
IF (NOT GetVarComponentInitialized (sym, tok)) AND IsUniqueWarning (tok)
THEN
GenerateNoteFlow (lst, i, warning) ;
IssueWarning (tok,
@ -766,7 +767,9 @@ END SetVarUninitialized ;
ComponentFindVar -
*)
PROCEDURE ComponentFindVar (sym: CARDINAL; VAR lvalue: BOOLEAN) : CARDINAL ;
PROCEDURE ComponentFindVar (sym: CARDINAL;
VAR lvalue: BOOLEAN;
tok: CARDINAL) : CARDINAL ;
VAR
nsym,
i : CARDINAL ;
@ -776,11 +779,17 @@ BEGIN
nsym := GetNth (sym, i) ;
lvalue := GetMode (nsym) = LeftValue ;
nsym := getLAlias (nsym) ;
IF (nsym # NulSym) AND IsVar (nsym)
IF nsym = Nil
THEN
MetaErrorT1 (tok,
"attempting to dereference {%1Wad} which will be a {%kNIL} pointer",
sym) ;
RETURN NulSym
ELSIF (nsym # NulSym) AND IsVar (nsym)
THEN
IF (nsym # sym) AND IsComponent (nsym)
THEN
RETURN ComponentFindVar (nsym, lvalue)
RETURN ComponentFindVar (nsym, lvalue, tok)
ELSE
RETURN nsym
END
@ -846,11 +855,12 @@ END ComponentBuildFieldList ;
deRefComponent -
*)
PROCEDURE deRefComponent (component: CARDINAL; lvalue: BOOLEAN) : CARDINAL ;
PROCEDURE deRefComponent (component: CARDINAL; lvalue: BOOLEAN;
sym: CARDINAL; tok: CARDINAL) : CARDINAL ;
BEGIN
IF lvalue
THEN
RETURN getContent (component)
RETURN getContent (component, sym, tok)
ELSE
RETURN component
END
@ -861,7 +871,7 @@ END deRefComponent ;
SetVarComponentInitialized -
*)
PROCEDURE SetVarComponentInitialized (sym: CARDINAL) ;
PROCEDURE SetVarComponentInitialized (sym: CARDINAL; tok: CARDINAL) ;
VAR
lvalue: BOOLEAN ;
i, n,
@ -869,8 +879,8 @@ VAR
vsym : CARDINAL ;
lst : List ;
BEGIN
vsym := ComponentFindVar (sym, lvalue) ;
vsym := deRefComponent (vsym, lvalue) ;
vsym := ComponentFindVar (sym, lvalue, tok) ;
vsym := deRefComponent (vsym, lvalue, sym, tok) ;
IF vsym # NulSym
THEN
IF Debugging
@ -911,7 +921,7 @@ END SetVarComponentInitialized ;
GetVarComponentInitialized -
*)
PROCEDURE GetVarComponentInitialized (sym: CARDINAL) : BOOLEAN ;
PROCEDURE GetVarComponentInitialized (sym: CARDINAL; tok: CARDINAL) : BOOLEAN ;
VAR
lvalue,
init : BOOLEAN ;
@ -919,13 +929,13 @@ VAR
vsym : CARDINAL ;
lst : List ;
BEGIN
component := ComponentFindVar (sym, lvalue) ;
component := ComponentFindVar (sym, lvalue, tok) ;
IF IsItemInList (ignoreList, component) OR IsExempt (component)
THEN
RETURN TRUE
ELSE
init := FALSE ;
vsym := deRefComponent (component, lvalue) ;
vsym := deRefComponent (component, lvalue, sym, tok) ;
IF vsym # NulSym
THEN
IF IsExempt (vsym)
@ -963,7 +973,8 @@ END Trace ;
then set the left and right initialization state.
*)
PROCEDURE SetVarInitialized (sym: CARDINAL; canDereference: BOOLEAN) ;
PROCEDURE SetVarInitialized (sym: CARDINAL; canDereference: BOOLEAN;
tok: CARDINAL) ;
BEGIN
IF IsVar (sym)
THEN
@ -971,7 +982,7 @@ BEGIN
IF IsComponent (sym)
THEN
Trace ("SetVarInitialized sym %d is a component and calling SetVarComponentInitialized", sym);
SetVarComponentInitialized (sym)
SetVarComponentInitialized (sym, tok)
ELSIF (GetMode (sym) = LeftValue) AND canDereference
THEN
Trace ("SetVarInitialized sym %d is LeftValue and canDeference and calling PutVarInitialized LeftValue and RightValue", sym);
@ -993,7 +1004,7 @@ END SetVarInitialized ;
doGetVarInitialized -
*)
PROCEDURE doGetVarInitialized (sym: CARDINAL) : BOOLEAN ;
PROCEDURE doGetVarInitialized (sym: CARDINAL; tok: CARDINAL) : BOOLEAN ;
BEGIN
IF IsVar (sym)
THEN
@ -1002,7 +1013,7 @@ BEGIN
RETURN TRUE
ELSIF IsComponent (sym)
THEN
RETURN GetVarComponentInitialized (sym)
RETURN GetVarComponentInitialized (sym, tok)
END ;
RETURN VarCheckReadInit (sym, GetMode (sym))
END ;
@ -1014,11 +1025,11 @@ END doGetVarInitialized ;
GetVarInitialized -
*)
PROCEDURE GetVarInitialized (sym: CARDINAL) : BOOLEAN ;
PROCEDURE GetVarInitialized (sym: CARDINAL; tok: CARDINAL) : BOOLEAN ;
VAR
init: BOOLEAN ;
BEGIN
init := doGetVarInitialized (sym) ;
init := doGetVarInitialized (sym, tok) ;
IF Debugging
THEN
IF init
@ -1061,7 +1072,7 @@ PROCEDURE CheckBinary (procSym,
BEGIN
CheckDeferredRecordAccess (procSym, op2tok, op2, FALSE, warning, lst, i) ;
CheckDeferredRecordAccess (procSym, op3tok, op3, FALSE, warning, lst, i) ;
SetVarInitialized (op1, FALSE)
SetVarInitialized (op1, FALSE, op1tok)
END CheckBinary ;
@ -1075,7 +1086,7 @@ PROCEDURE CheckUnary (procSym,
lst: List; i: CARDINAL) ;
BEGIN
CheckDeferredRecordAccess (procSym, rhstok, rhs, FALSE, warning, lst, i) ;
SetVarInitialized (lhs, FALSE)
SetVarInitialized (lhs, FALSE, lhstok)
END CheckUnary ;
@ -1093,13 +1104,13 @@ BEGIN
CheckDeferredRecordAccess (procSym, rhstok, rhs, FALSE, warning, bblst, i) ;
CheckDeferredRecordAccess (procSym, lhstok, lhs, FALSE, warning, bblst, i) ;
(* Now see if we know what lhs is pointing to and set fields if necessary. *)
vsym := getContent (getLAlias (lhs)) ;
vsym := getContent (getLAlias (lhs), lhs, lhstok) ;
IF (vsym # NulSym) AND (vsym # lhs) AND (GetSType (vsym) = type)
THEN
IF IsRecord (type)
THEN
(* Set all fields of vsym as initialized. *)
SetVarInitialized (vsym, FALSE)
SetVarInitialized (vsym, FALSE, lhstok)
ELSE
(* Set only the field assigned in vsym as initialized. *)
lst := ComponentCreateFieldList (rhs) ;
@ -1123,7 +1134,7 @@ VAR
content: CARDINAL ;
BEGIN
CheckDeferredRecordAccess (procSym, rhstok, rhs, FALSE, warning, lst, i) ;
content := getContent (getLAlias (rhs)) ;
content := getContent (getLAlias (rhs), rhs, rhstok) ;
IF content = NulSym
THEN
IncludeItemIntoList (ignoreList, lhs)
@ -1131,7 +1142,7 @@ BEGIN
CheckDeferredRecordAccess (procSym, rhstok, content, TRUE, warning, lst, i) ;
(* SetVarInitialized (lhs, IsVarAParam (rhs)) -- was -- *)
(* SetVarInitialized (lhs, FALSE) -- was -- *)
SetVarInitialized (lhs, VarCheckReadInit (content, RightValue))
SetVarInitialized (lhs, VarCheckReadInit (content, RightValue), lhstok)
END
END CheckIndrX ;
@ -1159,12 +1170,12 @@ VAR
BEGIN
CheckDeferredRecordAccess (procSym, exprtok, expr, FALSE, warning, bblst, i) ;
SetupLAlias (des, expr) ;
SetVarInitialized (des, FALSE) ;
SetVarInitialized (des, FALSE, destok) ;
(* Now see if we know what lhs is pointing to and set fields if necessary. *)
IF IsComponent (des)
THEN
vsym := ComponentFindVar (des, lvalue) ;
vsym := deRefComponent (vsym, lvalue) ;
vsym := ComponentFindVar (des, lvalue, destok) ;
vsym := deRefComponent (vsym, lvalue, des, destok) ;
IF vsym # NulSym
THEN
(* Set only the field assigned in vsym as initialized. *)
@ -1196,7 +1207,7 @@ END CheckComparison ;
PROCEDURE CheckAddr (procSym, ptrtok, ptr, contenttok, content: CARDINAL) ;
BEGIN
SetVarInitialized (ptr, GetVarInitialized (content)) ;
SetVarInitialized (ptr, GetVarInitialized (content, contenttok), ptrtok) ;
SetupIndr (ptr, content)
END CheckAddr ;
@ -1281,19 +1292,19 @@ BEGIN
FunctValueOp,
StandardFunctionOp,
HighOp,
SizeOp : SetVarInitialized (op1, FALSE) |
SizeOp : SetVarInitialized (op1, FALSE, op1tok) |
AddrOp : CheckAddr (procSym, op1tok, op1, op3tok, op3) |
ReturnValueOp : SetVarInitialized (op1, FALSE) |
ReturnValueOp : SetVarInitialized (op1, FALSE, op1tok) |
NewLocalVarOp : |
ParamOp : CheckDeferredRecordAccess (procSym, op2tok, op2, FALSE, warning, lst, i) ;
CheckDeferredRecordAccess (procSym, op3tok, op3, FALSE, warning, lst, i) ;
IF (op1 > 0) AND (op1 <= NoOfParam (op2)) AND
IsVarParam (op2, op1)
THEN
SetVarInitialized (op3, TRUE)
SetVarInitialized (op3, TRUE, op3tok)
END |
ArrayOp : CheckDeferredRecordAccess (procSym, op3tok, op3, FALSE, warning, lst, i) ;
SetVarInitialized (op1, TRUE) |
SetVarInitialized (op1, TRUE, op1tok) |
RecordFieldOp : CheckRecordField (procSym, op1tok, op1, op2tok, op2) |
LogicalShiftOp,
LogicalRotateOp,
@ -1318,7 +1329,7 @@ BEGIN
op1tok, op1, op2tok, op2, op3tok, op3, warning, lst, i) |
XIndrOp : CheckXIndr (procSym, op1tok, op1, op2, op3tok, op3, warning, lst, i) |
IndrXOp : CheckIndrX (procSym, op1tok, op1, op2, op3tok, op3, warning, lst, i) |
SaveExceptionOp : SetVarInitialized (op1, FALSE) |
SaveExceptionOp : SetVarInitialized (op1, FALSE, op1tok) |
RestoreExceptionOp: CheckDeferredRecordAccess (procSym, op1tok, op1, FALSE, warning, lst, i) |
SubrangeLowOp,
@ -1516,13 +1527,16 @@ END DumpBBSequence ;
PROCEDURE trashParam (trashQuad: CARDINAL) ;
VAR
op : QuadOperator ;
op1, op2, op3: CARDINAL ;
heapSym, ptr : CARDINAL ;
op : QuadOperator ;
op1, op2, op3 : CARDINAL ;
op1tok, op2tok, op3tok, qtok: CARDINAL ;
overflowChecking : BOOLEAN ;
heapSym, ptr : CARDINAL ;
BEGIN
IF trashQuad # 0
THEN
GetQuad (trashQuad, op, op1, op2, op3) ;
GetQuadOtok (trashQuad, qtok, op, op1, op2, op3, overflowChecking,
op1tok, op2tok, op3tok) ;
heapSym := GetQuadTrash (trashQuad) ;
IF Debugging
THEN
@ -1530,21 +1544,20 @@ BEGIN
END ;
IF heapSym # NulSym
THEN
SetVarInitialized (op3, FALSE) ;
ptr := getContent (getLAlias (op3)) ;
SetVarInitialized (op3, FALSE, op3tok) ;
ptr := getContent (getLAlias (op3), op3, op3tok) ;
IF ptr # NulSym
THEN
SetupIndr (ptr, heapSym) ;
SetVarInitialized (ptr, FALSE)
IF IsDeallocate (op2)
THEN
(* SetupLAlias (ptr, heapSym) *)
(* SetupIndr (ptr, Nil) *)
SetupLAlias (ptr, Nil)
ELSE
SetupIndr (ptr, heapSym)
END ;
SetVarInitialized (ptr, FALSE, op3tok)
END
(*
vsym := getLAlias (op3) ;
VarInitState (vsym) ;
VarInitState (heapSym) ;
PutVarInitialized (vsym, GetMode (vsym)) ;
PutVarInitialized (heapSym, LeftValue) ;
SetupLAlias (vsym, heapSym)
*)
END
END ;
DumpAliases
@ -1788,6 +1801,16 @@ BEGIN
END IsAllocate ;
(*
IsDeallocate - return TRUE is sym is DEALLOCATE.
*)
PROCEDURE IsDeallocate (sym: CARDINAL) : BOOLEAN ;
BEGIN
RETURN IsProcedure (sym) AND (GetSymName (sym) = MakeKey('DEALLOCATE'))
END IsDeallocate ;
(*
DetectTrash -
*)
@ -1803,7 +1826,7 @@ BEGIN
i := bbPtr^.start ;
LOOP
GetQuad (i, op, op1, op2, op3) ;
IF (op = ParamOp) AND (op1 = 1) AND IsAllocate (op2)
IF (op = ParamOp) AND (op1 = 1) AND (IsAllocate (op2) OR IsDeallocate (op2))
THEN
bbPtr^.trashQuad := i
END ;
@ -2078,8 +2101,9 @@ END getLAlias ;
PROCEDURE SetupLAlias (des, exp: CARDINAL) ;
BEGIN
IF IsVar (exp) AND
((GetMode (des) = LeftValue) OR IsReallyPointer (GetSType (des)))
IF (exp = Nil) OR
(IsVar (exp) AND
((GetMode (des) = LeftValue) OR IsReallyPointer (GetSType (des))))
THEN
addAlias (LArray, des, exp) ;
DumpAliases
@ -2098,12 +2122,21 @@ END SetupIndr ;
(*
getContent -
getContent - attempts to return the content pointed to by ptr.
sym is the original symbol and ptr will be the equivalent lvalue.
*)
PROCEDURE getContent (ptr: CARDINAL) : CARDINAL ;
PROCEDURE getContent (ptr: CARDINAL; sym: CARDINAL; tok: CARDINAL) : CARDINAL ;
BEGIN
RETURN doGetAlias (IndirectArray, ptr)
IF ptr = Nil
THEN
MetaErrorT1 (tok,
"attempting to dereference {%1Wad} which will be a {%kNIL} pointer",
sym) ;
RETURN NulSym
ELSE
RETURN doGetAlias (IndirectArray, ptr)
END
END getContent ;

24
gcc/testsuite/gm2/switches/uninit-variable-checking/procedures/fail/testdispose.mod Normal file
View file

@ -0,0 +1,24 @@
MODULE testdispose ;
FROM Storage IMPORT DEALLOCATE ;
TYPE
PtrToVec = POINTER TO RECORD
x, y: INTEGER ;
END ;
PROCEDURE test ;
VAR
ptr: PtrToVec ;
BEGIN
DISPOSE (ptr) ;
IF ptr^.x = 1
THEN
END
END test ;
BEGIN
test
END testdispose.

24
gcc/testsuite/gm2/switches/uninit-variable-checking/procedures/fail/testdispose2.mod Normal file
View file

@ -0,0 +1,24 @@
MODULE testdispose2 ;
FROM Storage IMPORT DEALLOCATE ;
TYPE
PtrToVec = POINTER TO RECORD
x, y: INTEGER ;
END ;
PROCEDURE test (ptr: PtrToVec) ;
BEGIN
DISPOSE (ptr) ;
IF ptr^.x = 1
THEN
END
END test ;
VAR
p: PtrToVec ;
BEGIN
test (p)
END testdispose2.

17
gcc/testsuite/gm2/switches/uninit-variable-checking/procedures/fail/testnil.mod Normal file
View file

@ -0,0 +1,17 @@
MODULE testnil ;
PROCEDURE test ;
VAR
p: POINTER TO CARDINAL ;
BEGIN
p := NIL ;
IF p^ = 1
THEN
END
END test ;
BEGIN
test
END testnil.