[cfe-commits] r49734 - in /cfe/trunk: include/clang/Analysis/Analyses/LiveVariables.h include/clang/Analysis/FlowSensitive/DataflowSolver.h lib/Analysis/LiveVariables.cpp lib/Analysis/UninitializedValues.cpp
Ted Kremenek
kremenek at apple.com
Tue Apr 15 11:35:30 PDT 2008
Author: kremenek
Date: Tue Apr 15 13:35:30 2008
New Revision: 49734
URL: http://llvm.org/viewvc/llvm-project?rev=49734&view=rev
Log:
Fix bug in terminator processing for uninitialized-values: simply ignore the terminator, don't reprocess it.
LiveVariables analysis now does a flow-insensitive analysis to determine what variables have their address taken; these variables are now always treated as being live.
The DataflowSolver now uses "SetTopValue()" when getting the initial value for the entry/exit block.
Modified:
cfe/trunk/include/clang/Analysis/Analyses/LiveVariables.h
cfe/trunk/include/clang/Analysis/FlowSensitive/DataflowSolver.h
cfe/trunk/lib/Analysis/LiveVariables.cpp
cfe/trunk/lib/Analysis/UninitializedValues.cpp
Modified: cfe/trunk/include/clang/Analysis/Analyses/LiveVariables.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/Analyses/LiveVariables.h?rev=49734&r1=49733&r2=49734&view=diff
==============================================================================
--- cfe/trunk/include/clang/Analysis/Analyses/LiveVariables.h (original)
+++ cfe/trunk/include/clang/Analysis/Analyses/LiveVariables.h Tue Apr 15 13:35:30 2008
@@ -28,6 +28,8 @@
struct ObserverTy;
+ // We keep dataflow state for declarations and block-level expressions;
+ typedef ExprDeclBitVector_Types::ValTy ValTy;
// We need to keep track of both declarations and CFGBlock-level expressions,
// (so that we don't explore such expressions twice). We also want
@@ -36,12 +38,10 @@
struct AnalysisDataTy : public ExprDeclBitVector_Types::AnalysisDataTy {
ObserverTy* Observer;
+ ValTy AlwaysLive;
AnalysisDataTy() : Observer(NULL) {}
};
-
- // We only keep actual dataflow state for declarations.
- typedef ExprDeclBitVector_Types::ValTy ValTy;
//===-----------------------------------------------------===//
// ObserverTy - Observer for uninitialized values queries.
@@ -61,6 +61,8 @@
class LiveVariables : public DataflowValues<LiveVariables_ValueTypes,
dataflow::backward_analysis_tag> {
+
+
public:
typedef LiveVariables_ValueTypes::ObserverTy ObserverTy;
Modified: cfe/trunk/include/clang/Analysis/FlowSensitive/DataflowSolver.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Analysis/FlowSensitive/DataflowSolver.h?rev=49734&r1=49733&r2=49734&view=diff
==============================================================================
--- cfe/trunk/include/clang/Analysis/FlowSensitive/DataflowSolver.h (original)
+++ cfe/trunk/include/clang/Analysis/FlowSensitive/DataflowSolver.h Tue Apr 15 13:35:30 2008
@@ -204,11 +204,31 @@
void EnqueueFirstBlock(const CFG& cfg, dataflow::backward_analysis_tag) {
WorkList.enqueue(&cfg.getExit());
}
+
+ void ResetValues(CFG& cfg, ValTy& V, const CFGBlock* B,
+ dataflow::forward_analysis_tag){
+
+ if (B == &cfg.getEntry())
+ TF.SetTopValue(V);
+ else
+ V.resetValues(D.getAnalysisData());
+ }
+
+ void ResetValues(CFG& cfg, ValTy& V, const CFGBlock* B,
+ dataflow::backward_analysis_tag){
+
+ if (B == &cfg.getExit())
+ TF.SetTopValue(V);
+ else
+ V.resetValues(D.getAnalysisData());
+ }
void ProcessMerge(CFG& cfg, const CFGBlock* B) {
+
+ ValTy& V = TF.getVal();
+ ResetValues(cfg, V, B, AnalysisDirTag());
+
// Merge dataflow values from all predecessors of this block.
- ValTy& V = TF.getVal();
- V.resetValues(D.getAnalysisData());
MergeOperatorTy Merge;
EdgeDataMapTy& M = D.getEdgeDataMap();
Modified: cfe/trunk/lib/Analysis/LiveVariables.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/LiveVariables.cpp?rev=49734&r1=49733&r2=49734&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/LiveVariables.cpp (original)
+++ cfe/trunk/lib/Analysis/LiveVariables.cpp Tue Apr 15 13:35:30 2008
@@ -19,6 +19,7 @@
#include "clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h"
#include "clang/Analysis/FlowSensitive/DataflowSolver.h"
#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Compiler.h"
#include <string.h>
@@ -27,6 +28,13 @@
using namespace clang;
//===----------------------------------------------------------------------===//
+// Useful constants.
+//===----------------------------------------------------------------------===//
+
+static const bool Alive = true;
+static const bool Dead = false;
+
+//===----------------------------------------------------------------------===//
// Dataflow initialization logic.
//===----------------------------------------------------------------------===//
@@ -35,9 +43,49 @@
: public CFGRecStmtDeclVisitor<RegisterDecls> {
LiveVariables::AnalysisDataTy& AD;
+
+ typedef llvm::SmallVector<VarDecl*, 20> AlwaysLiveTy;
+ AlwaysLiveTy AlwaysLive;
+
+
public:
- RegisterDecls(LiveVariables::AnalysisDataTy& ad) : AD(ad) {}
- void VisitVarDecl(VarDecl* VD) { AD.Register(VD); }
+ RegisterDecls(LiveVariables::AnalysisDataTy& ad) : AD(ad) {}
+
+ ~RegisterDecls() {
+
+ AD.AlwaysLive.resetValues(AD);
+
+ for (AlwaysLiveTy::iterator I = AlwaysLive.begin(), E = AlwaysLive.end();
+ I != E; ++ I)
+ AD.AlwaysLive(*I, AD) = Alive;
+ }
+
+ void VisitVarDecl(VarDecl* VD) {
+ // Register the VarDecl for tracking.
+ AD.Register(VD);
+
+ // Does the variable have global storage? If so, it is always live.
+ if (VD->hasGlobalStorage())
+ AlwaysLive.push_back(VD);
+ }
+
+ void VisitUnaryOperator(UnaryOperator* U) {
+ // Check for '&'. Any VarDecl whose value has its address-taken we
+ // treat as always being live (flow-insensitive).
+
+ Expr* E = U->getSubExpr()->IgnoreParenCasts();
+
+ if (U->getOpcode() == UnaryOperator::AddrOf)
+ if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(E))
+ if (VarDecl* VD = dyn_cast<VarDecl>(DR->getDecl())) {
+ AD.Register(VD);
+ AlwaysLive.push_back(VD);
+ return;
+ }
+
+ Visit(E);
+ }
+
CFG& getCFG() { return AD.getCFG(); }
};
} // end anonymous namespace
@@ -55,9 +103,6 @@
//===----------------------------------------------------------------------===//
namespace {
-
-static const bool Alive = true;
-static const bool Dead = false;
class VISIBILITY_HIDDEN TransferFuncs : public CFGRecStmtVisitor<TransferFuncs>{
LiveVariables::AnalysisDataTy& AD;
@@ -75,6 +120,11 @@
void VisitUnaryOperator(UnaryOperator* U);
void Visit(Stmt *S);
void VisitTerminator(Stmt* S);
+
+ void SetTopValue(LiveVariables::ValTy& V) {
+ V = AD.AlwaysLive;
+ }
+
};
void TransferFuncs::Visit(Stmt *S) {
@@ -151,7 +201,11 @@
// Assigning to a variable?
if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(LHS->IgnoreParens())) {
- LiveState(DR->getDecl(), AD) = Dead;
+
+ // Update liveness inforamtion.
+ unsigned bit = AD.getIdx(DR->getDecl());
+ LiveState.getDeclBit(bit) = Dead | AD.AlwaysLive.getDeclBit(bit);
+
if (AD.Observer) { AD.Observer->ObserverKill(DR); }
// Handle things like +=, etc., which also generate "uses"
@@ -170,7 +224,10 @@
// possibly be live before they are declared.
for (ScopedDecl* D = DS->getDecl(); D != NULL; D = D->getNextDeclarator())
if (VarDecl* VD = dyn_cast<VarDecl>(D)) {
- LiveState(D, AD) = Dead;
+
+ // Update liveness information.
+ unsigned bit = AD.getIdx(VD);
+ LiveState.getDeclBit(bit) = Dead | AD.AlwaysLive.getDeclBit(bit);
if (Expr* Init = VD->getInit())
Visit(Init);
Modified: cfe/trunk/lib/Analysis/UninitializedValues.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Analysis/UninitializedValues.cpp?rev=49734&r1=49733&r2=49734&view=diff
==============================================================================
--- cfe/trunk/lib/Analysis/UninitializedValues.cpp (original)
+++ cfe/trunk/lib/Analysis/UninitializedValues.cpp Tue Apr 15 13:35:30 2008
@@ -58,13 +58,15 @@
UninitializedValues::ValTy V;
UninitializedValues::AnalysisDataTy& AD;
public:
- TransferFuncs(UninitializedValues::AnalysisDataTy& ad) : AD(ad) {
- V.resetValues(AD);
- }
+ TransferFuncs(UninitializedValues::AnalysisDataTy& ad) : AD(ad) {}
UninitializedValues::ValTy& getVal() { return V; }
CFG& getCFG() { return AD.getCFG(); }
+ void SetTopValue(UninitializedValues::ValTy& X) {
+ X.resetValues(AD);
+ }
+
bool VisitDeclRefExpr(DeclRefExpr* DR);
bool VisitBinaryOperator(BinaryOperator* B);
bool VisitUnaryOperator(UnaryOperator* U);
@@ -76,7 +78,7 @@
bool Visit(Stmt *S);
bool BlockStmt_VisitExpr(Expr* E);
- void VisitTerminator(Stmt* T) { Visit(T); }
+ void VisitTerminator(Stmt* T) { }
BlockVarDecl* FindBlockVarDecl(Stmt* S);
};
@@ -216,12 +218,9 @@
// In our transfer functions we take the approach that any
// combination of unintialized values, e.g. Unitialized + ___ = Unitialized.
//
-// Merges take the opposite approach.
-//
-// In the merge of dataflow values we prefer unsoundness, and
-// prefer false negatives to false positives. At merges, if a value for a
-// tracked Decl is EVER initialized in any of the predecessors we treat it as
-// initialized at the confluence point.
+// Merges take the same approach, preferring soundness. At a confluence point,
+// if any predecessor has a variable marked uninitialized, the value is
+// uninitialized at the confluence point.
//===----------------------------------------------------------------------===//
namespace {
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