[AST] Reimplement Stmt::getLoc{Start,End} to dispatch to subclass overloads.

 - getSourceRange() can be very expensive, we should try to avoid it if at all possible.

In conjunction with the previous commit I measured a ~2% speedup on 403.gcc/combine.c and a 3% speedup on OmniGroupFrameworks/NSBezierPath-OAExtensions.m.

llvm-svn: 152411

1 files changed, 3 insertions, 1 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 0266cd63bbc..8e2e64faf1d 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -94,6 +94,8 @@ bool Expr::isKnownToHaveBooleanValue() const {
 
 // Amusing macro metaprogramming hack: check whether a class provides
 // a more specific implementation of getExprLoc().
+//
+// See also Stmt.cpp:{getLocStart(),getLocEnd()}.
 namespace {
   /// This implementation is used when a class provides a custom
   /// implementation of getExprLoc.
@@ -110,7 +112,7 @@ namespace {
   template <class E>
   SourceLocation getExprLocImpl(const Expr *expr,
                                 SourceLocation (Expr::*v)() const) {
-    return static_cast<const E*>(expr)->getSourceRange().getBegin();
+    return static_cast<const E*>(expr)->getLocStart();
   }
 }