[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: 371834

1 files changed, 69 insertions, 0 deletions

diff --git a/clang/lib/AST/Interp/Disasm.cpp b/clang/lib/AST/Interp/Disasm.cpp
new file mode 100644
index 00000000000..e77a825eb1f
--- /dev/null
+++ b/clang/lib/AST/Interp/Disasm.cpp
@@ -0,0 +1,69 @@
+//===--- Disasm.cpp - Disassembler for bytecode functions -------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Dump method for Function which disassembles the bytecode.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Function.h"
+#include "Opcode.h"
+#include "PrimType.h"
+#include "Program.h"
+#include "clang/AST/DeclCXX.h"
+#include "llvm/Support/Compiler.h"
+
+using namespace clang;
+using namespace clang::interp;
+
+LLVM_DUMP_METHOD void Function::dump() const { dump(llvm::errs()); }
+
+LLVM_DUMP_METHOD void Function::dump(llvm::raw_ostream &OS) const {
+  if (F) {
+    if (auto *Cons = dyn_cast<CXXConstructorDecl>(F)) {
+      const std::string &Name = Cons->getParent()->getNameAsString();
+      OS << Name << "::" << Name << ":\n";
+    } else {
+      OS << F->getNameAsString() << ":\n";
+    }
+  } else {
+    OS << "<<expr>>\n";
+  }
+
+  OS << "frame size: " << getFrameSize() << "\n";
+  OS << "arg size:   " << getArgSize() << "\n";
+  OS << "rvo:        " << hasRVO() << "\n";
+
+  auto PrintName = [&OS](const char *Name) {
+    OS << Name;
+    for (long I = 0, N = strlen(Name); I < 30 - N; ++I) {
+      OS << ' ';
+    }
+  };
+
+  for (CodePtr Start = getCodeBegin(), PC = Start; PC != getCodeEnd();) {
+    size_t Addr = PC - Start;
+    auto Op = PC.read<Opcode>();
+    OS << llvm::format("%8d", Addr) << " ";
+    switch (Op) {
+#define GET_DISASM
+#include "Opcodes.inc"
+#undef GET_DISASM
+    }
+  }
+}
+
+LLVM_DUMP_METHOD void Program::dump() const { dump(llvm::errs()); }
+
+LLVM_DUMP_METHOD void Program::dump(llvm::raw_ostream &OS) const {
+  for (auto &Func : Funcs) {
+    Func.second->dump();
+  }
+  for (auto &Anon : AnonFuncs) {
+    Anon->dump();
+  }
+}