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When adding assignment expressions to the set of block-level expressions, only 

include the assignment expressions whose result (as in the value of the
expression) is used by other expressions.

llvm-svn: 46361
This commit is contained in:
Ted Kremenek 2008-01-25 18:28:28 +00:00
parent 6532001fc0
commit 463b726698
1 changed files with 35 additions and 8 deletions
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43
clang/AST/CFG.cpp
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@ -991,26 +991,53 @@ namespace {
typedef llvm::DenseMap<const Stmt*,unsigned> BlkExprMapTy;
}
static void FindSubExprAssignments(Stmt* S, llvm::SmallPtrSet<Expr*,50>& Set) {
for (Stmt::child_iterator I=S->child_begin(), E=S->child_end(); I!=E; ++I) {
if (BinaryOperator* B = dyn_cast<BinaryOperator>(*I))
if (B->isAssignmentOp()) Set.insert(B);
FindSubExprAssignments(*I, Set);
}
}
static BlkExprMapTy* PopulateBlkExprMap(CFG& cfg) {
BlkExprMapTy* M = new BlkExprMapTy();
// Look for assignments that are used as subexpressions. These are the
// only assignments that we want to register as a block-level expression.
llvm::SmallPtrSet<Expr*,50> SubExprAssignments;
for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I)
for (CFGBlock::iterator BI=I->begin(), EI=I->end(); BI != EI; ++BI)
if (const Expr* E = dyn_cast<Expr>(*BI)) {
unsigned x = M->size();
(*M)[E] = x;
FindSubExprAssignments(*BI, SubExprAssignments);
// Special handling for statement expressions. The last statement
// in the statement expression is also a block-level expr.
if (const StmtExpr* S = dyn_cast<StmtExpr>(E)) {
// Iterate over the statements again on identify the Expr* and Stmt* at
// the block-level that are block-level expressions.
for (CFG::iterator I=cfg.begin(), E=cfg.end(); I != E; ++I)
for (CFGBlock::iterator BI=I->begin(), EI=I->end(); BI != EI; ++BI)
if (Expr* E = dyn_cast<Expr>(*BI)) {
if (BinaryOperator* B = dyn_cast<BinaryOperator>(E)) {
// Assignment expressions that are not nested within another
// expression are really "statements" whose value is never
// used by another expression.
if (B->isAssignmentOp() && !SubExprAssignments.count(E))
continue;
}
else if (const StmtExpr* S = dyn_cast<StmtExpr>(E)) {
// Special handling for statement expressions. The last statement
// in the statement expression is also a block-level expr.
const CompoundStmt* C = S->getSubStmt();
if (!C->body_empty()) {
x = M->size();
unsigned x = M->size();
(*M)[C->body_back()] = x;
}
}
}
unsigned x = M->size();
(*M)[E] = x;
}
return M;
}