[modula2] Uninitialized variable static analysis improvements

This patch fixes many limitations of the uninitialized static analysis.
NEW is understood, local variable pointers and non var parameters
will be tracked.

gcc/ChangeLog:

	* doc/gm2.texi (Semantic checking): Change example testwithptr
	to testnew6.

gcc/m2/ChangeLog:

	* Make-lang.in: Minor formatting change.
	* gm2-compiler/M2GCCDeclare.mod
	(DeclareUnboundedProcedureParameters): Rename local variables.
	(WalkUnboundedProcedureParameters): Rename local variables.
	(DoVariableDeclaration): Avoid declaration of a variable if
	it is on the heap (used by static analysis only).
	* gm2-compiler/M2GenGCC.mod: Formatting.
	* gm2-compiler/M2Quads.def (GetQuadTrash): New procedure function.
	* gm2-compiler/M2Quads.mod (GetQuadTrash): New procedure function.
	(QuadFrame): Add Trash field.
	(BuildRealFuncProcCall): Detect ALLOCATE and DEALLOCATE and create
	a heap variable for parameter 1 saving it as the trashed variable
	for static analysis.
	(GenQuadOTrash): New procedure.
	(DisplayQuadRange): Bugfix.  Write the scope number.
	* gm2-compiler/M2SymInit.mod: Rewritten to separate LValue
	equivalence from LValue to RValue pairings.  Comprehensive
	detection of variant record implemented.  Allow dereferencing
	of pointers through LValue/RValue chains.
	* gm2-compiler/SymbolTable.def (PutVarHeap): New procedure.
	(IsVarHeap): New procedure function.
	(ForeachParamSymDo): New procedure.
	* gm2-compiler/SymbolTable.mod (PutVarHeap): New procedure.
	(IsVarHeap): New procedure function.
	(ForeachParamSymDo): New procedure.
	(MakeVariableForParam): Reformatted.
	(CheckForUnknownInModule): Reformatted.
	(SymVar): Add field Heap.
	(MakeVar): Assign Heap to FALSE.

gcc/testsuite/ChangeLog:

	* gm2/switches/uninit-variable-checking/pass/assignparam.mod: New test.
	* gm2/switches/uninit-variable-checking/pass/tiny.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/switches-uninit-variable-checking-procedures-fail.exp:
	New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew2.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew3.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew4.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew5.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testnew6.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/fail/testptrptr.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/assignparam2.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/switches-uninit-variable-checking-procedures-pass.exp:
	New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testnew5.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testnew6.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testparamlvalue.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testparamrvalue.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testproc.mod: New test.
	* gm2/switches/uninit-variable-checking/procedures/pass/testptrptr.mod: New test.

Signed-off-by: Gaius Mulley <gaiusmod2@gmail.com>

1 files changed, 12 insertions, 13 deletions

diff --git a/gcc/doc/gm2.texi b/gcc/doc/gm2.texi
index 8d5d95f..9f7f8ce 100644
--- a/gcc/doc/gm2.texi
+++ b/gcc/doc/gm2.texi
@@ -1471,7 +1471,7 @@ plugin is invoked.
 The @samp{-Wuninit-variable-checking} can be used to identify
 uninitialized variables within the first basic block in a procedure.
 The checking is limited to variables so long as they are
-not an array or set or a variant record.
+not an array or set or a variant record or var parameter.
 
 The following example detects whether a sub component within a record
 is uninitialized.
@@ -1551,22 +1551,20 @@ access expression before it has been initialized
 @end example
 
 @example
-MODULE testwithptr ;
+MODULE testnew6 ;
 
-FROM SYSTEM IMPORT ADR ;
+FROM Storage IMPORT ALLOCATE ;
 
 TYPE
-   PtrToVec = POINTER TO Vec ;
-   Vec = RECORD
-            x, y: CARDINAL ;
-         END ;
+   PtrToVec = POINTER TO RECORD
+                            x, y: INTEGER ;
+                         END ;
 
 PROCEDURE test ;
 VAR
    p: PtrToVec ;
-   v: Vec ;
 BEGIN
-   p := ADR (v) ;
+   NEW (p) ;
    WITH p^ DO
       x := 1 ;
       x := 2   (* Deliberate typo, user meant y.  *)
@@ -1576,16 +1574,17 @@ BEGIN
    END
 END test ;
 
+
 BEGIN
    test
-END testwithptr.
+END testnew6.
 @end example
 
 @example
-gm2 -c -Wuninit-variable-checking testwithptr.mod
-testwithptr.mod:26:9: warning: In procedure ‘test’: attempting to
+$ gm2 -g -c -Wuninit-variable-checking testnew6.mod
+testnew6.mod:19:9: warning: In procedure ‘test’: attempting to
 access expression before it has been initialized
-   26 |    IF p^.y = 2
+   19 |    IF p^.y = 2
       |       ~~^~
 @end example