[Clang Interpreter] Initial patch for the constexpr interpreter

Summary:
This patch introduces the skeleton of the constexpr interpreter,
capable of evaluating a simple constexpr functions consisting of
if statements. The interpreter is described in more detail in the
RFC. Further patches will add more features.

Reviewers: Bigcheese, jfb, rsmith

Subscribers: bruno, uenoku, ldionne, Tyker, thegameg, tschuett, dexonsmith, mgorny, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64146

llvm-svn: 370476

1 files changed, 39 insertions, 0 deletions

diff --git a/clang/lib/AST/Interp/Source.cpp b/clang/lib/AST/Interp/Source.cpp
new file mode 100644
index 00000000000..4bec8781263
--- /dev/null
+++ b/clang/lib/AST/Interp/Source.cpp
@@ -0,0 +1,39 @@
+//===--- Source.cpp - Source expression tracking ----------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "Source.h"
+#include "clang/AST/Expr.h"
+
+using namespace clang;
+using namespace clang::interp;
+
+SourceLocation SourceInfo::getLoc() const {
+  if (const Expr *E = asExpr())
+    return E->getExprLoc();
+  if (const Stmt *S = asStmt())
+    return S->getBeginLoc();
+  if (const Decl *D = asDecl())
+    return D->getBeginLoc();
+  return SourceLocation();
+}
+
+const Expr *SourceInfo::asExpr() const {
+  if (auto *S = Source.dyn_cast<const Stmt *>())
+    return dyn_cast<Expr>(S);
+  return nullptr;
+}
+
+const Expr *SourceMapper::getExpr(Function *F, CodePtr PC) const {
+  if (const Expr *E = getSource(F, PC).asExpr())
+    return E;
+  llvm::report_fatal_error("missing source expression");
+}
+
+SourceLocation SourceMapper::getLocation(Function *F, CodePtr PC) const {
+  return getSource(F, PC).getLoc();
+}