diff --git a/ast.cpp b/ast.cpp
index 81070eab..023e4ba9 100644
--- a/ast.cpp
+++ b/ast.cpp
@@ -273,3 +273,19 @@ Stmt *
 TypeCheck(Stmt *stmt) {
     return (Stmt *)TypeCheck((ASTNode *)stmt);
 }
+
+
+static bool
+lCostCallback(ASTNode *node, void *c) {
+    int *cost = (int *)c;
+    *cost += node->EstimateCost();
+    return true;
+}
+
+
+int
+EstimateCost(ASTNode *root) {
+    int cost = 0;
+    WalkAST(root, lCostCallback, NULL, &cost);
+    return cost;
+}
diff --git a/ast.h b/ast.h
index 68fc9a03..0c3d4b64 100644
--- a/ast.h
+++ b/ast.h
@@ -66,6 +66,9 @@ public:
         pointer in place of the original ASTNode *. */
     virtual ASTNode *TypeCheck() = 0;
 
+    /** Estimate the execution cost of the node (not including the cost of
+        the children.  The value returned should be based on the COST_*
+        enumerant values defined in ispc.h. */
     virtual int EstimateCost() const = 0;
 
     /** All AST nodes must track the file position where they are
@@ -127,14 +130,18 @@ extern Expr *Optimize(Expr *);
     to a Stmt *). */ 
 extern Stmt *Optimize(Stmt *);
 
-/* Perform type-checking on the given AST (or portion of one), returning a
-   pointer to the root of the resulting AST. */
+/** Perform type-checking on the given AST (or portion of one), returning a
+    pointer to the root of the resulting AST. */
 extern ASTNode *TypeCheck(ASTNode *root);
 
-/* Convenience version of TypeCheck() for Expr *s that returns an Expr *. */
+/** Convenience version of TypeCheck() for Expr *s that returns an Expr *. */
 extern Expr *TypeCheck(Expr *);
 
-/* Convenience version of TypeCheck() for Stmt *s that returns an Stmt *. */
+/** Convenience version of TypeCheck() for Stmt *s that returns an Stmt *. */
 extern Stmt *TypeCheck(Stmt *);
 
+/** Returns an estimate of the execution cost of the tree starting at
+    the given root. */
+extern int EstimateCost(ASTNode *root);
+
 #endif // ISPC_AST_H
diff --git a/expr.cpp b/expr.cpp
index ade233f1..af6acd28 100644
--- a/expr.cpp
+++ b/expr.cpp
@@ -989,7 +989,7 @@ UnaryExpr::TypeCheck() {
 
 int
 UnaryExpr::EstimateCost() const {
-    return (expr ? expr->EstimateCost() : 0) + COST_SIMPLE_ARITH_LOGIC_OP;
+    return COST_SIMPLE_ARITH_LOGIC_OP;
 }
 
 
@@ -1885,10 +1885,8 @@ BinaryExpr::TypeCheck() {
 
 int
 BinaryExpr::EstimateCost() const {
-    return ((arg0 ? arg0->EstimateCost() : 0) +
-            (arg1 ? arg1->EstimateCost() : 0) +
-            ((op == Div || op == Mod) ? COST_COMPLEX_ARITH_OP : 
-                                        COST_SIMPLE_ARITH_LOGIC_OP));
+    return (op == Div || op == Mod) ? COST_COMPLEX_ARITH_OP : 
+                                      COST_SIMPLE_ARITH_LOGIC_OP;
 }
 
 
@@ -2204,15 +2202,12 @@ AssignExpr::TypeCheck() {
 
 int
 AssignExpr::EstimateCost() const {
-    int cost = ((lvalue ? lvalue->EstimateCost() : 0) +
-                (rvalue ? rvalue->EstimateCost() : 0));
-    cost += COST_ASSIGN;
     if (op == Assign)
-        return cost;
+        return COST_ASSIGN;
     if (op == DivAssign || op == ModAssign)
-        return cost + COST_COMPLEX_ARITH_OP;
+        return COST_ASSIGN + COST_COMPLEX_ARITH_OP;
     else
-        return cost + COST_SIMPLE_ARITH_LOGIC_OP;
+        return COST_ASSIGN + COST_SIMPLE_ARITH_LOGIC_OP;
 }
 
 
@@ -2637,7 +2632,7 @@ FunctionCallExpr::TypeCheck() {
         if (fse->ResolveOverloads(args->pos, argTypes, &argCouldBeNULL) == false)
             return NULL;
 
-        func = fse->TypeCheck();
+        func = ::TypeCheck(fse);
         if (func == NULL)
             return NULL;
 
@@ -2742,28 +2737,20 @@ FunctionCallExpr::TypeCheck() {
 
 int
 FunctionCallExpr::EstimateCost() const {
-    int callCost = 0;
-    if (isLaunch) {
-        callCost = COST_TASK_LAUNCH;
-        if (launchCountExpr != NULL)
-            callCost += launchCountExpr->EstimateCost();
-    }
+    if (isLaunch)
+        return COST_TASK_LAUNCH;
     else if (dynamic_cast<FunctionSymbolExpr *>(func) == NULL) {
         // it's going through a function pointer
         const Type *fpType = func->GetType();
         if (fpType != NULL) {
             Assert(dynamic_cast<const PointerType *>(fpType) != NULL);
             if (fpType->IsUniformType())
-                callCost = COST_FUNPTR_UNIFORM;
+                return COST_FUNPTR_UNIFORM;
             else 
-                callCost = COST_FUNPTR_VARYING;
+                return COST_FUNPTR_VARYING;
         }
     }
-    else
-        // regular function call
-        callCost = COST_FUNCALL;
-
-    return (args ? args->EstimateCost() : 0) + callCost;
+    return COST_FUNCALL;
 }
 
 
@@ -2880,12 +2867,7 @@ ExprList::GetConstant(const Type *type) const {
 
 int
 ExprList::EstimateCost() const {
-    int cost = 0;
-    for (unsigned int i = 0; i < exprs.size(); ++i) {
-        if (exprs[i] != NULL)
-            cost += exprs[i]->EstimateCost();
-    }
-    return cost;
+    return 0;
 }
 
 
diff --git a/func.cpp b/func.cpp
index 0327bff9..61dfb784 100644
--- a/func.cpp
+++ b/func.cpp
@@ -277,7 +277,7 @@ Function::emitCode(FunctionEmitContext *ctx, llvm::Function *function,
         ctx->SetDebugPos(code->pos);
         ctx->AddInstrumentationPoint("function entry");
 
-        int costEstimate = code->EstimateCost();
+        int costEstimate = EstimateCost(code);
         Debug(code->pos, "Estimated cost for function \"%s\" = %d\n", 
               sym->name.c_str(), costEstimate);
 
diff --git a/stmt.cpp b/stmt.cpp
index b3ec0c39..e799fc0b 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -107,7 +107,7 @@ ExprStmt::Print(int indent) const {
 
 int
 ExprStmt::EstimateCost() const {
-    return expr ? expr->EstimateCost() : 0;
+    return 0;
 }
 
 
@@ -467,11 +467,7 @@ DeclStmt::Print(int indent) const {
 
 int
 DeclStmt::EstimateCost() const {
-    int cost = 0;
-    for (unsigned int i = 0; i < vars.size(); ++i)
-        if (vars[i].init != NULL)
-            cost += vars[i].init->EstimateCost();
-    return cost;
+    return 0;
 }
 
 
@@ -577,15 +573,11 @@ IfStmt::TypeCheck() {
 
 int
 IfStmt::EstimateCost() const {
-    int ifcost = 0;
     const Type *type;
-    if (test && (type = test->GetType()) != NULL)
-        ifcost = type->IsUniformType() ? COST_UNIFORM_IF : COST_VARYING_IF;
+    if (test == NULL || (type = test->GetType()) != NULL)
+        return 0;
 
-    return ifcost +
-        ((test ? test->EstimateCost() : 0) +
-         (trueStmts ? trueStmts->EstimateCost() : 0) +
-         (falseStmts ? falseStmts->EstimateCost() : 0));
+    return type->IsUniformType() ? COST_UNIFORM_IF : COST_VARYING_IF;
 }
 
 
@@ -766,9 +758,10 @@ IfStmt::emitVaryingIf(FunctionEmitContext *ctx, llvm::Value *ltest) const {
         //
         // where our use of blend for conditional assignments doesn't check
         // for the 'all lanes' off case.
-        bool costIsAcceptable = ((trueStmts ? trueStmts->EstimateCost() : 0) + 
-                                 (falseStmts ? falseStmts->EstimateCost() : 0)) < 
-            PREDICATE_SAFE_IF_STATEMENT_COST;
+        int trueFalseCost = (::EstimateCost(trueStmts) + 
+                             ::EstimateCost(falseStmts));
+        bool costIsAcceptable = (trueFalseCost <
+                                 PREDICATE_SAFE_IF_STATEMENT_COST);
 
         bool safeToRunWithAllLanesOff = true;
         WalkAST(trueStmts, lCheckAllOffSafety, NULL, &safeToRunWithAllLanesOff);
@@ -1146,8 +1139,11 @@ DoStmt::TypeCheck() {
 
 int
 DoStmt::EstimateCost() const {
-    return ((testExpr ? testExpr->EstimateCost() : 0) +
-            (bodyStmts ? bodyStmts->EstimateCost() : 0));
+    bool uniformTest = testExpr ? testExpr->GetType()->IsUniformType() :
+        (!g->opt.disableUniformControlFlow &&
+         !lHasVaryingBreakOrContinue(bodyStmts));
+
+    return uniformTest ? COST_UNIFORM_LOOP : COST_VARYING_LOOP;
 }
 
 
@@ -1336,11 +1332,7 @@ ForStmt::EstimateCost() const {
         (!g->opt.disableUniformControlFlow &&
          !lHasVaryingBreakOrContinue(stmts));
 
-    return ((init ? init->EstimateCost() : 0) +
-            (test ? test->EstimateCost() : 0) +
-            (step ? step->EstimateCost() : 0) +
-            (stmts ? stmts->EstimateCost() : 0) +
-            (uniformTest ? COST_UNIFORM_LOOP : COST_VARYING_LOOP));
+    return uniformTest ? COST_UNIFORM_LOOP : COST_VARYING_LOOP;
 }
 
 
@@ -1827,8 +1819,7 @@ ForeachStmt::TypeCheck() {
 
 int
 ForeachStmt::EstimateCost() const {
-    return dimVariables.size() * (COST_UNIFORM_LOOP + COST_SIMPLE_ARITH_LOGIC_OP) +
-        (stmts ? stmts->EstimateCost() : 0);
+    return dimVariables.size() * (COST_UNIFORM_LOOP + COST_SIMPLE_ARITH_LOGIC_OP);
 }
 
 
@@ -1908,7 +1899,7 @@ ReturnStmt::TypeCheck() {
 
 int
 ReturnStmt::EstimateCost() const {
-    return COST_RETURN + (val ? val->EstimateCost() : 0);
+    return COST_RETURN;
 }
 
 
@@ -1947,11 +1938,7 @@ StmtList::TypeCheck() {
 
 int
 StmtList::EstimateCost() const {
-    int cost = 0;
-    for (unsigned int i = 0; i < stmts.size(); ++i)
-        if (stmts[i])
-            cost += stmts[i]->EstimateCost();
-    return cost;
+    return 0;
 }
 
 
@@ -2156,7 +2143,7 @@ PrintStmt::TypeCheck() {
 
 int
 PrintStmt::EstimateCost() const {
-    return COST_FUNCALL + (values ? values->EstimateCost() : 0);
+    return COST_FUNCALL;
 }
 
 
@@ -2243,6 +2230,6 @@ AssertStmt::TypeCheck() {
 
 int
 AssertStmt::EstimateCost() const {
-    return (expr ? expr->EstimateCost() : 0) + COST_ASSERT;
+    return COST_ASSERT;
 }