[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, 66 insertions, 0 deletions

diff --git a/clang/lib/AST/Stmt.cpp b/clang/lib/AST/Stmt.cpp
index 0deaaa83bad..7907e565dde 100644
--- a/clang/lib/AST/Stmt.cpp
+++ b/clang/lib/AST/Stmt.cpp
@@ -176,6 +176,72 @@ SourceRange Stmt::getSourceRange() const {
   llvm_unreachable("unknown statement kind!");
 }
 
+// Amusing macro metaprogramming hack: check whether a class provides
+// a more specific implementation of getLocStart() and getLocEnd().
+//
+// See also Expr.cpp:getExprLoc().
+namespace {
+  /// This implementation is used when a class provides a custom
+  /// implementation of getLocStart.
+  template <class S, class T>
+  SourceLocation getLocStartImpl(const Stmt *stmt,
+                                 SourceLocation (T::*v)() const) {
+    return static_cast<const S*>(stmt)->getLocStart();
+  }
+
+  /// This implementation is used when a class doesn't provide a custom
+  /// implementation of getLocStart.  Overload resolution should pick it over
+  /// the implementation above because it's more specialized according to
+  /// function template partial ordering.
+  template <class S>
+  SourceLocation getLocStartImpl(const Stmt *stmt,
+                                SourceLocation (Stmt::*v)() const) {
+    return static_cast<const S*>(stmt)->getSourceRange().getBegin();
+  }
+
+  /// This implementation is used when a class provides a custom
+  /// implementation of getLocEnd.
+  template <class S, class T>
+  SourceLocation getLocEndImpl(const Stmt *stmt,
+                               SourceLocation (T::*v)() const) {
+    return static_cast<const S*>(stmt)->getLocEnd();
+  }
+
+  /// This implementation is used when a class doesn't provide a custom
+  /// implementation of getLocEnd.  Overload resolution should pick it over
+  /// the implementation above because it's more specialized according to
+  /// function template partial ordering.
+  template <class S>
+  SourceLocation getLocEndImpl(const Stmt *stmt,
+                               SourceLocation (Stmt::*v)() const) {
+    return static_cast<const S*>(stmt)->getSourceRange().getEnd();
+  }
+}
+
+SourceLocation Stmt::getLocStart() const {
+  switch (getStmtClass()) {
+  case Stmt::NoStmtClass: llvm_unreachable("statement without class");
+#define ABSTRACT_STMT(type)
+#define STMT(type, base) \
+  case Stmt::type##Class: \
+    return getLocStartImpl<type>(this, &type::getLocStart);
+#include "clang/AST/StmtNodes.inc"
+  }
+  llvm_unreachable("unknown statement kind");
+}
+
+SourceLocation Stmt::getLocEnd() const {
+  switch (getStmtClass()) {
+  case Stmt::NoStmtClass: llvm_unreachable("statement without class");
+#define ABSTRACT_STMT(type)
+#define STMT(type, base) \
+  case Stmt::type##Class: \
+    return getLocEndImpl<type>(this, &type::getLocEnd);
+#include "clang/AST/StmtNodes.inc"
+  }
+  llvm_unreachable("unknown statement kind");
+}
+
 void CompoundStmt::setStmts(ASTContext &C, Stmt **Stmts, unsigned NumStmts) {
   if (this->Body)
     C.Deallocate(Body);