From 04a913b9584319d3f5d68c08168c217b8ffd186f Mon Sep 17 00:00:00 2001
From: Chris Lattner <sabre@nondot.org>
Date: Fri, 31 Aug 2007 22:09:40 +0000
Subject: [PATCH] implement code generation for scalar stmt expressions.

llvm-svn: 41656
---
 clang/CodeGen/CGExprScalar.cpp  |  7 +++++++
 clang/CodeGen/CGStmt.cpp        | 23 ++++++++++++++++++++---
 clang/CodeGen/CodeGenFunction.h |  2 +-
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/clang/CodeGen/CGExprScalar.cpp b/clang/CodeGen/CGExprScalar.cpp
index 1499054b6cce..db0e6bf492e5 100644
--- a/clang/CodeGen/CGExprScalar.cpp
+++ b/clang/CodeGen/CGExprScalar.cpp
@@ -129,6 +129,8 @@ public:
     return CGF.EmitCallExpr(E).getVal();
   }
   
+  Value *VisitStmtExpr(const StmtExpr *E);
+  
   // Unary Operators.
   Value *VisitPrePostIncDec(const UnaryOperator *E, bool isInc, bool isPre);
   Value *VisitUnaryPostDec(const UnaryOperator *E) {
@@ -437,6 +439,11 @@ Value *ScalarExprEmitter::EmitCastExpr(const Expr *E, QualType DestTy) {
                                        DestTy);
 }
 
+Value *ScalarExprEmitter::VisitStmtExpr(const StmtExpr *E) {
+  return CGF.EmitCompoundStmt(*E->getSubStmt(), true).getVal();
+}
+
+
 //===----------------------------------------------------------------------===//
 //                             Unary Operators
 //===----------------------------------------------------------------------===//
diff --git a/clang/CodeGen/CGStmt.cpp b/clang/CodeGen/CGStmt.cpp
index 04c9c1d3eb70..85a6ca8705ed 100644
--- a/clang/CodeGen/CGStmt.cpp
+++ b/clang/CodeGen/CGStmt.cpp
@@ -60,12 +60,29 @@ void CodeGenFunction::EmitStmt(const Stmt *S) {
   }
 }
 
-void CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S) {
+/// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
+/// this captures the expression result of the last sub-statement and returns it
+/// (for use by the statement expression extension).
+RValue CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast) {
   // FIXME: handle vla's etc.
+  if (S.body_empty() || !isa<Expr>(S.body_back())) GetLast = false;
   
-  for (CompoundStmt::const_body_iterator I = S.body_begin(), E = S.body_end();
-       I != E; ++I)
+  for (CompoundStmt::const_body_iterator I = S.body_begin(),
+       E = S.body_end()-GetLast; I != E; ++I)
     EmitStmt(*I);
+  
+  
+  if (!GetLast)
+    return RValue::get(0);
+    
+  const Expr *Last = cast<Expr>(S.body_back());
+  if (!hasAggregateLLVMType(Last->getType()))
+    return RValue::get(EmitScalarExpr(Last));
+  assert(0 && "Unimp");
+  //else if (Last->getType()->isComplexType())
+  //  EmitComplexExpr(Last);
+  //else
+  //  EmitAggExpr(E, 0, false);
 }
 
 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB) {
diff --git a/clang/CodeGen/CodeGenFunction.h b/clang/CodeGen/CodeGenFunction.h
index af8d80bbb279..a597f4326869 100644
--- a/clang/CodeGen/CodeGenFunction.h
+++ b/clang/CodeGen/CodeGenFunction.h
@@ -265,7 +265,7 @@ public:
   //===--------------------------------------------------------------------===//
 
   void EmitStmt(const Stmt *S);
-  void EmitCompoundStmt(const CompoundStmt &S);
+  RValue EmitCompoundStmt(const CompoundStmt &S, bool GetLast = false);
   void EmitLabelStmt(const LabelStmt &S);
   void EmitGotoStmt(const GotoStmt &S);
   void EmitIfStmt(const IfStmt &S);