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Revert "[BoundsWidening] Determine checked scope specifier per statement (#1139)" #1141

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Aug 5, 2021
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Revert "[BoundsWidening] Determine checked scope specifier per statement (#1139)" #1141

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21 changes: 4 additions & 17 deletions clang/include/clang/Sema/BoundsWideningAnalysis.h
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Original file line number Diff line number Diff line change
Expand Up @@ -82,17 +82,14 @@ namespace clang {
Lexicographic Lex;
BoundsVarsTy &BoundsVarsLower;
BoundsVarsTy &BoundsVarsUpper;
CheckedScopeMapTy &CheckedScopeMap;

public:
BoundsWideningUtil(Sema &SemaRef, CFG *Cfg,
ASTContext &Ctx, Lexicographic Lex,
BoundsVarsTy &BoundsVarsLower,
BoundsVarsTy &BoundsVarsUpper,
CheckedScopeMapTy &CheckedScopeMap) :
BoundsVarsTy &BoundsVarsUpper) :
SemaRef(SemaRef), Cfg(Cfg), Ctx(Ctx), Lex(Lex),
BoundsVarsLower(BoundsVarsLower), BoundsVarsUpper(BoundsVarsUpper),
CheckedScopeMap(CheckedScopeMap) {}
BoundsVarsLower(BoundsVarsLower), BoundsVarsUpper(BoundsVarsUpper) {}

// Check if B2 is a subrange of B1.
// @param[in] B1 is the first range.
Expand Down Expand Up @@ -175,14 +172,6 @@ namespace clang {
// expression.
const VarDecl *GetNullTermPtrInExpr(Expr *E) const;

// Update the checked scope specifier for the current statement if it has
// changed from that of the previous statement.
// @param[in] CurrStmt is the current statement.
// @param[out] CSS is updated with the checked scope specifier for the
// current statement if it has changed from that of the previous statement.
void UpdateCheckedScopeSpecifier(const Stmt *CurrStmt,
CheckedScopeSpecifier &CSS) const;

// Invoke IgnoreValuePreservingOperations to strip off casts.
// @param[in] E is the expression whose casts must be stripped.
// @return E with casts stripped off.
Expand Down Expand Up @@ -343,13 +332,11 @@ namespace clang {

BoundsWideningAnalysis(Sema &SemaRef, CFG *Cfg,
BoundsVarsTy &BoundsVarsLower,
BoundsVarsTy &BoundsVarsUpper,
CheckedScopeMapTy &CheckedScopeMap) :
BoundsVarsTy &BoundsVarsUpper) :
SemaRef(SemaRef), Cfg(Cfg), Ctx(SemaRef.Context),
Lex(Lexicographic(Ctx, nullptr)), OS(llvm::outs()),
BWUtil(BoundsWideningUtil(SemaRef, Cfg, Ctx, Lex,
BoundsVarsLower, BoundsVarsUpper,
CheckedScopeMap)) {}
BoundsVarsLower, BoundsVarsUpper)) {}

// Run the dataflow analysis to widen bounds for null-terminated arrays.
// @param[in] FD is the current function.
Expand Down
7 changes: 0 additions & 7 deletions clang/include/clang/Sema/CheckedCAnalysesPrepass.h
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Expand Up @@ -38,9 +38,6 @@ namespace clang {
// of F in whose declared bounds expressions F occurs.
using BoundsSiblingFieldsTy = llvm::DenseMap<const FieldDecl *, FieldSetTy>;

// CheckedScopeMapTy maps a statement to its checked scope specifier.
using CheckedScopeMapTy = llvm::DenseMap<const Stmt *, CheckedScopeSpecifier>;

struct PrepassInfo {
// VarUses maps each VarDecl V in a function to the DeclRefExpr (if any)
// that is the first use of V, if V fulfills the following conditions:
Expand Down Expand Up @@ -85,10 +82,6 @@ namespace clang {
// a deterministic iteration order we must remember to sort the keys as
// well as the values.
BoundsSiblingFieldsTy BoundsSiblingFields;

// A map of statements to their checked scope specifiers. An entry in this
// map is made only when the checked scope specifier changes.
CheckedScopeMapTy CheckedScopeMap;
};
} // end namespace clang
#endif
15 changes: 3 additions & 12 deletions clang/lib/Sema/BoundsWideningAnalysis.cpp
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Expand Up @@ -82,7 +82,6 @@ BoundsMapTy BoundsWideningAnalysis::GetOutOfLastStmt(
// statement and return the StmtOut for the last statement of the block.

BoundsMapTy StmtOut = EB->In;
CheckedScopeSpecifier CSS = CheckedScopeSpecifier::CSS_None;

for (CFGBlock::const_iterator I = EB->Block->begin(),
E = EB->Block->end();
Expand All @@ -94,9 +93,6 @@ BoundsMapTy BoundsWideningAnalysis::GetOutOfLastStmt(
if (!CurrStmt)
continue;

// Update the checked scope specifier for the current statement.
BWUtil.UpdateCheckedScopeSpecifier(CurrStmt, CSS);

// The In of the current statement is the value of StmtOut computed so far.
BoundsMapTy InOfCurrStmt = StmtOut;

Expand Down Expand Up @@ -125,6 +121,9 @@ BoundsMapTy BoundsWideningAnalysis::GetOutOfLastStmt(
Expr *OriginalLValue = std::get<1>(ValuesToReplaceInBounds);
VarSetTy PtrsWithAffectedBounds = std::get<2>(ValuesToReplaceInBounds);

// TODO: Determine the Checked scope for each statement.
CheckedScopeSpecifier CSS = CheckedScopeSpecifier::CSS_None;

for (const VarDecl *V : PtrsWithAffectedBounds) {
auto StmtInIt = InOfCurrStmt.find(V);
if (StmtInIt == InOfCurrStmt.end())
Expand Down Expand Up @@ -1420,14 +1419,6 @@ const VarDecl *BoundsWideningUtil::GetNullTermPtrInExpr(Expr *E) const {
return nullptr;
}

void BoundsWideningUtil::UpdateCheckedScopeSpecifier(
const Stmt *CurrStmt, CheckedScopeSpecifier &CSS) const {

auto ScopeIt = CheckedScopeMap.find(CurrStmt);
if (ScopeIt != CheckedScopeMap.end())
CSS = ScopeIt->second;
}

Expr *BoundsWideningUtil::IgnoreCasts(const Expr *E) const {
return Lex.IgnoreValuePreservingOperations(Ctx, const_cast<Expr *>(E));
}
Expand Down
46 changes: 0 additions & 46 deletions clang/lib/Sema/CheckedCAnalysesPrepass.cpp
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Expand Up @@ -277,52 +277,6 @@ class PrepassHelper : public RecursiveASTVisitor<PrepassHelper> {
return ProcessWhereClause(S->getWhereClause());
}

bool VisitCompoundStmt(CompoundStmt *CS) {
if (!CS)
return true;

// Get the checked scope specifier for the current compound statement.
CheckedScopeSpecifier CSS = CS->getCheckedSpecifier();

bool FirstStmt = true;

// A compound statement is of the form {stmt stmt}. Iterate through the
// nested statements of the compound statement.
for (auto I = CS->body_begin(), E = CS->body_end(); I != E; ++I) {
const Stmt *CurrStmt = *I;

// If this is a compound statement the RecursiveASTVisitor will visit
// it later. So we don't need to process it now.
if (isa<CompoundStmt>(CurrStmt)) {
continue;

// Else if this is a label statement. Basic blocks may begin at label
// statements. We need to be able to update the CSS value correctly at
// the beginning of a basic block as we are assured of ordered lookup
// only within a basic block (i.e. the first statement of a basic block
// may be accessed out of statement-order). The AST only stores the
// sub-statement of a label statement. So accordingly we store the CSS
// for the sub-statement.
} else if (auto *L = dyn_cast<LabelStmt>(CurrStmt)) {
Info.CheckedScopeMap[L->getSubStmt()] = CSS;

// Else if this is the first statement in a compound statement store
// its checked scope specifier.
} else if (FirstStmt) {
Info.CheckedScopeMap[CurrStmt] = CSS;

// Else if the previous statement was a compound statement store the
// checked scope specifier of the current statement.
} else if (isa<CompoundStmt>(*(I - 1))) {
Info.CheckedScopeMap[CurrStmt] = CSS;
}

FirstStmt = false;
}

return true;
}

void DumpBoundsVars(FunctionDecl *FD) {
PrintDeclMap<const VarDecl *>(FD, "BoundsVars Lower",
Info.BoundsVarsLower);
Expand Down
6 changes: 2 additions & 4 deletions clang/lib/Sema/SemaBounds.cpp
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Expand Up @@ -2576,8 +2576,7 @@ namespace {
Facts(Facts),
BoundsWideningAnalyzer(BoundsWideningAnalysis(SemaRef, Cfg,
Info.BoundsVarsLower,
Info.BoundsVarsUpper,
Info.CheckedScopeMap)),
Info.BoundsVarsUpper)),
AbstractSetMgr(AbstractSetManager(SemaRef, Info.VarUses)),
BoundsSiblingFields(Info.BoundsSiblingFields),
IncludeNullTerminator(false) {}
Expand All @@ -2594,8 +2593,7 @@ namespace {
Facts(Facts),
BoundsWideningAnalyzer(BoundsWideningAnalysis(SemaRef, nullptr,
Info.BoundsVarsLower,
Info.BoundsVarsUpper,
Info.CheckedScopeMap)),
Info.BoundsVarsUpper)),
AbstractSetMgr(AbstractSetManager(SemaRef, Info.VarUses)),
BoundsSiblingFields(Info.BoundsSiblingFields),
IncludeNullTerminator(false) {}
Expand Down