Modified the notion of "Block-level expressions" in CFGs to include Stmt*. This

is because GNU-style Statement-expressions cause the last statement in the
statement-expression to act like an expression.

We now have two notions: block-level statements and block-level expressions.

The former are all Stmt* that appear in the list of statements in CFGBlocks. The
latter is the subset of the former; these block-level statements are used as
subexpressions somewhere in the AST. CFG::isBlockExpr() returns true for the
latter, not the former (previously isBlockExpr() always returned true for
non-Expr Stmt*).

Modified the LiveVariables analysis to also track liveness state for block-level
expressions (using the updated definition of block-level expressions).

Modified the dataflow solver so that when it records values for block-level
statements, it records the dataflow value *before* the transfer function for a
Stmt* is evaluated (not after). This is more in sync in what clients will want.

Modified CFGStmtVisitor to record the current block-level statement.

llvm-svn: 46143

1 files changed, 14 insertions, 1 deletions

diff --git a/clang/Analysis/LiveVariables.cpp b/clang/Analysis/LiveVariables.cpp
index ff4224a06fa..5bd72b42af4 100644
--- a/clang/Analysis/LiveVariables.cpp
+++ b/clang/Analysis/LiveVariables.cpp
@@ -77,7 +77,16 @@ void TransferFuncs::Visit(Stmt *S) {
   if (AD.Observer)
     AD.Observer->ObserveStmt(S,AD,LiveState);
   
-  static_cast<CFGStmtVisitor<TransferFuncs>*>(this)->Visit(S);
+
+  if (S == getCurrentBlkStmt()) {
+    StmtVisitor<TransferFuncs,void>::Visit(S);
+    if (getCFG().isBlkExpr(S)) LiveState(S,AD) = Dead;
+  }
+  else if (!getCFG().isBlkExpr(S))
+    StmtVisitor<TransferFuncs,void>::Visit(S);
+  else
+    // For block-level expressions, mark that they are live.
+    LiveState(S,AD) = Alive;
 }
 
 void TransferFuncs::VisitDeclRefExpr(DeclRefExpr* DR) {
@@ -186,6 +195,10 @@ bool LiveVariables::isLive(const ValTy& Live, const VarDecl* D) const {
   return Live(D,getAnalysisData());
 }
 
+bool LiveVariables::isLive(const Stmt* Loc, const Stmt* StmtVal) const {
+  return getStmtData(Loc)(StmtVal,getAnalysisData());
+}
+
 //===----------------------------------------------------------------------===//
 // printing liveness state for debugging
 //