[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: 370636

1 files changed, 46 insertions, 0 deletions

diff --git a/clang/lib/AST/Interp/ByteCodeGenError.h b/clang/lib/AST/Interp/ByteCodeGenError.h
new file mode 100644
index 00000000000..a4fa4917705
--- /dev/null
+++ b/clang/lib/AST/Interp/ByteCodeGenError.h
@@ -0,0 +1,46 @@
+//===--- ByteCodeGenError.h - Byte code generation error ----------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_INTERP_BYTECODEGENERROR_H
+#define LLVM_CLANG_AST_INTERP_BYTECODEGENERROR_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/Stmt.h"
+#include "clang/Basic/SourceLocation.h"
+#include "llvm/Support/Error.h"
+
+namespace clang {
+namespace interp {
+
+/// Error thrown by the compiler.
+struct ByteCodeGenError : public llvm::ErrorInfo<ByteCodeGenError> {
+public:
+  ByteCodeGenError(SourceLocation Loc) : Loc(Loc) {}
+  ByteCodeGenError(const Stmt *S) : ByteCodeGenError(S->getBeginLoc()) {}
+  ByteCodeGenError(const Decl *D) : ByteCodeGenError(D->getBeginLoc()) {}
+
+  void log(raw_ostream &OS) const override { OS << "unimplemented feature"; }
+
+  const SourceLocation &getLoc() const { return Loc; }
+
+  static char ID;
+
+private:
+  // Start of the item where the error occurred.
+  SourceLocation Loc;
+
+  // Users are not expected to use error_code.
+  std::error_code convertToErrorCode() const override {
+    return llvm::inconvertibleErrorCode();
+  }
+};
+
+} // namespace interp
+} // namespace clang
+
+#endif