From fc2954419d754c2dd8c32eb1fd971d8bc800fdbb Mon Sep 17 00:00:00 2001
From: Matt Pharr <matt.pharr@intel.com>
Date: Sat, 15 Oct 2011 13:52:08 -0700
Subject: [PATCH] Update cost model to include "if" overhead in "if" statement
 calculation.

---
 ispc.h   |  2 ++
 stmt.cpp | 12 +++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/ispc.h b/ispc.h
index ba5ce632..a2cacc99 100644
--- a/ispc.h
+++ b/ispc.h
@@ -367,6 +367,8 @@ enum {
     COST_TASK_LAUNCH = 16,
     COST_TYPECAST_COMPLEX = 4,
     COST_TYPECAST_SIMPLE = 1,
+    COST_UNIFORM_IF = 2,
+    COST_VARYING_IF = 3,
     COST_UNIFORM_LOOP = 4,
     COST_VARYING_LOOP = 6,
     COST_ASSERT = 8,
diff --git a/stmt.cpp b/stmt.cpp
index b2c43b4d..364f931b 100644
--- a/stmt.cpp
+++ b/stmt.cpp
@@ -541,9 +541,15 @@ Stmt *IfStmt::TypeCheck() {
 
 int
 IfStmt::EstimateCost() const {
-    return ((test ? test->EstimateCost() : 0) +
-            (trueStmts ? trueStmts->EstimateCost() : 0) +
-            (falseStmts ? falseStmts->EstimateCost() : 0));
+    int ifcost = 0;
+    const Type *type;
+    if (test && (type = test->GetType()) != NULL)
+        ifcost = type->IsUniformType() ? COST_UNIFORM_IF : COST_VARYING_IF;
+
+    return ifcost +
+        ((test ? test->EstimateCost() : 0) +
+         (trueStmts ? trueStmts->EstimateCost() : 0) +
+         (falseStmts ? falseStmts->EstimateCost() : 0));
 }