[modula2] Improve uninitialized variable analysis by combining basic blocks

This patch combines basic blocks for static analysis of uninitialized
variables providing that they are not the top of a loop, are not reached
by a conditional and are not reached after a procedure call.  It also
avoids checking array accesses for static analysis.  Finally the patch
adds switch modifiers to allow static analysis to include conditional
branches for subsequent basic block analysis.

gcc/ChangeLog:

	* doc/gm2.texi (-Wuninit-variable-checking=) New item.

gcc/m2/ChangeLog:

	* gm2-compiler/M2BasicBlock.def (InitBasicBlocksFromRange): New
	parameter ScopeSym.
	* gm2-compiler/M2BasicBlock.mod (ConvertQuads2BasicBlock): New
	parameter ScopeSym.
	(InitBasicBlocksFromRange): New	parameter ScopeSym.  Call
	ConvertQuads2BasicBlock with ScopeSym.
	(DisplayBasicBlocks): Uncomment.
	* gm2-compiler/M2Code.mod: Replace VariableAnalysis with
	ScopeBlockVariableAnalysis.
	(InitialDeclareAndOptiomize): Add parameter scope.
	(SecondDeclareAndOptimize): Add parameter scope.
	* gm2-compiler/M2GCCDeclare.mod (DeclareConstructor): Add scope
	parameter to DeclareTypesConstantsProceduresInRange.
	(DeclareTypesConstantsProceduresInRange): New parameter scope.
	Pass scope to DisplayQuadRange.  Reformatted.
	* gm2-compiler/M2GenGCC.def (ConvertQuadsToTree): New parameter
	scope.
	* gm2-compiler/M2GenGCC.mod (ConvertQuadsToTree): New parameter
	scope.
	* gm2-compiler/M2Optimize.mod (KnownReachable): New parameter
	scope.
	* gm2-compiler/M2Options.def (SetUninitVariableChecking): Add
	arg parameter.
	* gm2-compiler/M2Options.mod (SetUninitVariableChecking): Add
	arg parameter and set boolean UninitVariableChecking and
	UninitVariableConditionalChecking.
	(UninitVariableConditionalChecking): New boolean set to FALSE.
	* gm2-compiler/M2Quads.def (IsGoto): New procedure function.
	(DisplayQuadRange): Add scope parameter.
	(LoopAnalysis): Add scope parameter.
	* gm2-compiler/M2Quads.mod: Import PutVarArrayRef.
	(IsGoto): New procedure function.
	(LoopAnalysis): Add scope parameter and use MetaErrorT1 instead
	of WarnStringAt.
	(BuildStaticArray): Call PutVarArrayRef.
	(BuildDynamicArray): Call PutVarArrayRef.
	(DisplayQuadRange): Add scope parameter.
	(GetM2OperatorDesc): Add relational condition cases.
	* gm2-compiler/M2Scope.def (ScopeProcedure): Add parameter.
	* gm2-compiler/M2Scope.mod (DisplayScope): Pass scopeSym to
	DisplayQuadRange.
	(ForeachScopeBlockDo): Pass scopeSym to p.
	* gm2-compiler/M2SymInit.def (VariableAnalysis): Rename to ...
	(ScopeBlockVariableAnalysis): ... this.
	* gm2-compiler/M2SymInit.mod (ScopeBlockVariableAnalysis): Add
	scope parameter.
	(bbEntry): New pointer to record.
	(bbArray): New array.
	(bbFreeList): New variable.
	(errorList): New list.
	(IssueConditional): New procedure.
	(GenerateNoteFlow): New procedure.
	(IssueWarning): New procedure.
	(IsUniqueWarning): New procedure.
	(CheckDeferredRecordAccess): Re-implement.
	(CheckBinary): Add warning and lst parameters.
	(CheckUnary): Add warning and lst parameters.
	(CheckXIndr): Add warning and lst parameters.
	(CheckIndrX): Add warning and lst parameters.
	(CheckBecomes): Add warning and lst parameters.
	(CheckComparison): Add warning and lst parameters.
	(CheckReadBeforeInitQuad): Add warning and lst parameters to all
	Check procedures.  Add all case quadruple clauses.
	(FilterCheckReadBeforeInitQuad): Add warning and lst parameters.
	(CheckReadBeforeInitFirstBasicBlock): Add warning and lst parameters.
	(bbArrayKill): New procedure.
	(DumpBBEntry): New procedure.
	(DumpBBArray): New procedure.
	(DumpBBSequence): New procedure.
	(TestBBSequence): New procedure.
	(CreateBBPermultations): New procedure.
	(ScopeBlockVariableAnalysis): New procedure.
	(GetOp3): New procedure.
	(GenerateCFG): New procedure.
	(NewEntry): New procedure.
	(AppendEntry): New procedure.
	(init): Initialize bbFreeList and errorList.
	* gm2-compiler/SymbolTable.def (PutVarArrayRef): New procedure.
	(IsVarArrayRef): New procedure function.
	* gm2-compiler/SymbolTable.mod (SymVar): ArrayRef new field.
	(MakeVar): Set ArrayRef to FALSE.
	(PutVarArrayRef): New procedure.
	(IsVarArrayRef): New procedure function.
	* gm2-gcc/init.cc (_M2_M2SymInit_init): New prototype.
	(init_PerCompilationInit): Add call to _M2_M2SymInit_init.
	* gm2-gcc/m2options.h (M2Options_SetUninitVariableChecking):
	New definition.
	* gm2-lang.cc (gm2_langhook_handle_option): Add new case
	OPT_Wuninit_variable_checking_.
	* lang.opt: Wuninit-variable-checking= new entry.

gcc/testsuite/ChangeLog:

	* gm2/switches/uninit-variable-checking/cascade/fail/cascadedif.mod: New test.
	* gm2/switches/uninit-variable-checking/cascade/fail/switches-uninit-variable-checking-cascade-fail.exp:
	New test.

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

1 files changed, 11 insertions, 0 deletions

diff --git a/gcc/doc/gm2.texi b/gcc/doc/gm2.texi
index ae87434..8d5d95f 100644
--- a/gcc/doc/gm2.texi
+++ b/gcc/doc/gm2.texi
@@ -664,6 +664,17 @@ issue a warning if a variable is used before it is initialized.
 The checking only occurs in the first basic block in each procedure.
 It does not check parameters, array types or set types.
 
+@item -Wuninit-variable-checking=all,known,cond
+issue a warning if a variable is used before it is initialized.
+The checking will only occur in the first basic block in each
+procedure if @samp{known} is specified.  If @samp{cond} or @samp{all}
+is specified then checking continues into conditional branches of the
+flow graph.  All checking will stop when a procedure call is invoked
+or the top of a loop is encountered.
+The option @samp{-Wall} will turn on this flag with
+@samp{-Wuninit-variable-checking=known}.
+The @samp{-Wuninit-variable-checking=all} will increase compile time.
+
 @c the following warning options are complete but need to be
 @c regression tested against all other front ends
 @c to ensure the options do not conflict.