lib/Renderscript/RSAddDebugInfoPass.cpp

/*
 * Copyright 2015, The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "bcc/Assert.h"
#include "bcc/Renderscript/RSTransforms.h"

#include <llvm/Pass.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/DIBuilder.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/InstIterator.h>
#include <llvm/IR/Instructions.h>
#include <llvm/IR/MDBuilder.h>
#include <llvm/IR/Module.h>
#include <llvm/IR/Type.h>
#include <llvm/Transforms/Utils/BasicBlockUtils.h>

namespace {

const char DEBUG_SOURCE_PATH[] = "/opt/renderscriptdebugger/1";
const char DEBUG_GENERATED_FILE[] = "generated.rs";

/*
 * LLVM pass to attach debug information to the bits of code
 * generated by the compiler.
 */
class RSAddDebugInfoPass : public llvm::ModulePass {

public:
  // Pass ID
  static char ID;

  RSAddDebugInfoPass() : ModulePass(ID) {
  }

  virtual bool runOnModule(llvm::Module &Module) {
    // Set up the debug info builder.
    llvm::DIBuilder DebugInfo(Module);
    DebugInfo.createCompileUnit(llvm::dwarf::DW_LANG_C99,
                                DEBUG_GENERATED_FILE, DEBUG_SOURCE_PATH,
                                "RS", false, "", 0);

    // Attach DI metadata to each generated function.
    for (llvm::Function &Func : Module)
      if (Func.getName().endswith(".expand"))
        attachDebugInfo(DebugInfo, Func);

    DebugInfo.finalize();

    return true;
  }

private:

  /// @brief Add debug information to a generated function.
  ///
  /// This function is used to attach source file and line information
  /// to the generated function code.
  void attachDebugInfo(llvm::DIBuilder &DebugInfo, llvm::Function &Func) {
    llvm::DIFile *sourceFileName =
      DebugInfo.createFile(DEBUG_GENERATED_FILE, DEBUG_SOURCE_PATH);

    // Fabricated function type
    llvm::MDTuple *nullMD = llvm::MDTuple::get(Func.getParent()->getContext(),
                        { DebugInfo.createUnspecifiedType("void") });

    // Create function-level debug metadata.
    llvm::DIScope *GeneratedScope = DebugInfo.createFunction(
        sourceFileName, // scope
        Func.getName(), Func.getName(),
        sourceFileName, 1,
        DebugInfo.createSubroutineType(sourceFileName, nullMD),
        false, true, 1, 0, false, &Func
    );

    // Attach location inforamtion to each instruction in the function
    for (llvm::inst_iterator Inst    = llvm::inst_begin(Func),
                             InstEnd = llvm::inst_end(Func);
                             Inst != InstEnd;
                             ++Inst) {
      Inst->setDebugLoc(llvm::DebugLoc::get(1, 1, GeneratedScope));
    }
  }

}; // end class RSAddDebugInfoPass

char RSAddDebugInfoPass::ID = 0;
static llvm::RegisterPass<RSAddDebugInfoPass> X("addrsdi", "Add RS DebugInfo Pass");

} // end anonymous namespace

namespace bcc {

llvm::ModulePass * createRSAddDebugInfoPass() {
  return new RSAddDebugInfoPass();
}

} // end namespace bcc