[llvm] IR2Builder tool for converting LLVM IR files into C++ IRBuilder API (PR #117129)

[Jason Eckhardt via llvm-commits]

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+//===-- ir2builder.cpp - Transpiler from IR to builder API ------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a pass, which converts LLVM IR into llvm::IRBuilder
+// API in textual form.
+//
+// This tool can be used to simplify IR construction using IRBuilder by
+// writing the IR by hand and then converting it using this pass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/APFloat.h"
+#include "llvm/ADT/APInt.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/CallingConv.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/ModuleSummaryIndex.h"
+#include "llvm/Support/AtomicOrdering.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/InitLLVM.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/ToolOutputFile.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cctype>
+#include <cmath>
+#include <cstdint>
+#include <sstream>
+
+using namespace llvm;
+
+cl::OptionCategory Ir2BCat("ir2builder Options");
+
+/** LLVM IR to convert */
+static cl::opt<std::string>
+    InputFilename(cl::Positional, cl::desc("<input .ll file>"), cl::init("-"));
+
+/**
+ * Output file for the generated C++ code.
+ * If not set then stdout will be used.
+ */
+static cl::opt<std::string> OutputFilename("o",
+                                           cl::desc("Override output filename"),
+                                           cl::value_desc("filename"),
+                                           cl::cat(Ir2BCat));
+
+/** Set this when you don't use `using namespace llvm` (don't forget :: at the
+ * end) */
+static cl::opt<std::string> ScopePrefix(
+    "scope-prefix",
+    cl::desc(
+        "All generated calls to LLVM API will be prefixed with this scope. The "
+        "scope has to end with '::' (e.g.: '-scope-prefix=llvm::')"),
+    cl::cat(Ir2BCat), cl::init(""));
+
+/** Set this to your variable name for IRBuilder instance */
+static cl::opt<std::string> BuilderName(
+    "builder-name",
+    cl::desc("IRBuilder variable name that will be used in generated code"),
+    cl::cat(Ir2BCat), cl::init("Builder"));
+
+/** Set this to your LLVMContext variable name */
+static cl::opt<std::string> ContextName(
+    "context-name",
+    cl::desc("Context variable name that will be used in generated code"),
+    cl::cat(Ir2BCat), cl::init("Ctx"));
+
+/** Set this to your llvm::Module * name */
+static cl::opt<std::string> ModuleName(
+    "module-name",
+    cl::desc("Module variable name that will be used in generated code"),
+    cl::cat(Ir2BCat), cl::init("Mod"));
+
+/** Set this if you want custom data layout */
+static cl::opt<std::string> ClDataLayout("data-layout",
+                                         cl::desc("data layout string to use"),
+                                         cl::value_desc("layout-string"),
+                                         cl::init(""), cl::cat(Ir2BCat));
+
+/**
+ * This will generate fully compilable C++ program with main, which will
+ * use generated calls to create the original LLVM IR.
+ * Main purpose of this is to use it for testing and verification that
+ * generated program is correct and compilable.
+ * For example you can generate the code, run this program and then use
+ * llvm-diff to see if it matches the original:
+ *     ```
+ *     ./ir2builder code.ll --runnable > main.cpp &&
+ *     g++ main.cpp `./llvm-conf --cxxflags --ldflags --system-libs --libs core`
+ * -I /llvm/include/ -o main &&
+ *     ./main > generated.ll &&
+ *     ./llvm-diff code.ll generated.ll
+ *     ```
+ */
+static cl::opt<bool> GenerateRunnable(
+    "runnable", cl::desc("Generates whole cpp compilable program with main"),
+    cl::init(false), cl::cat(Ir2BCat));
+
+/**
+ * Disables verification of loaded llvm IR.
+ * Keep in mind that this will most likely result in C++ error as it probably
+ * won't be possible to create Builder calls for this.
+ */
+static cl::opt<bool>
+    DisableVerify("disable-verify", cl::Hidden,
+                  cl::desc("Do not run verifier on input LLVM (dangerous!)"),
+                  cl::cat(Ir2BCat));
+
+/**
+ * Sets the order of traversal for the LLVM IR.
+ * When enabled the traversal will be in reverse post order, which can handle
+ * when values are defined after (text-wise) their use.
+ * On the other hand using just linear traversal will also include parts that
+ * are outside of the graph (dead blocks).
+ */
+static cl::opt<bool>
+    UseRPO("use-rpo",
+           cl::desc("Traverses IR in reverse post order. This can help with "
+                    "\"was not declared\" errors"),
+           cl::init(true), cl::cat(Ir2BCat));
+
+/**
+ * @brief Transpiler from LLVM IR into IRBuilder API calls
+ * The main purpose for this class is to hold variable counter and variable
+ * names for needed resources, such as LLVMContext.
+ */
+class IR2Builder {
+private:
+  unsigned long varI = 0;
+  std::string llvmPrefix;
+  std::string builder;
+  std::string ctx;
+  std::string modName;
----------------
nvjle wrote:

Forgot to mention-- you can automatically identify (and correct) many naming and similar issues with the `clang-tidy` tool, something like `clang-tidy -p my_build_dir ir2builder.cpp ` (add `--fix` to apply suggested fixes, otherwise the tool will just show them).

https://github.com/llvm/llvm-project/pull/117129