tools/llvm-exegesis/lib/Assembler.h

   1 //===-- Assembler.h ---------------------------------------------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 ///
  10 /// \file
  11 /// Defines classes to assemble functions composed of a single basic block of
  12 /// MCInsts.
  13 ///
  14 //===----------------------------------------------------------------------===//
  15
  16 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H
  17 #define LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H
  18
  19 #include <memory>
  20
  21 #include "llvm/ADT/ArrayRef.h"
  22 #include "llvm/ADT/BitVector.h"
  23 #include "llvm/CodeGen/MachineFunction.h"
  24 #include "llvm/CodeGen/MachineModuleInfo.h"
  25 #include "llvm/ExecutionEngine/ExecutionEngine.h"
  26 #include "llvm/IR/LLVMContext.h"
  27 #include "llvm/IR/Module.h"
  28 #include "llvm/MC/MCInst.h"
  29 #include "llvm/Object/Binary.h"
  30 #include "llvm/Object/ObjectFile.h"
  31 #include "llvm/Support/raw_ostream.h"
  32 #include "llvm/Target/TargetMachine.h"
  33
  34 namespace exegesis {
  35
  36 class ExegesisTarget;
  37
  38 // Gather the set of reserved registers (depends on function's calling
  39 // convention and target machine).
  40 llvm::BitVector getFunctionReservedRegs(const llvm::TargetMachine &TM);
  41
  42 // A simple object storing the value for a particular register.
  43 struct RegisterValue {
  44   unsigned Register;
  45   llvm::APInt Value;
  46 };
  47
  48 // Creates a temporary `void foo(char*)` function containing the provided
  49 // Instructions. Runs a set of llvm Passes to provide correct prologue and
  50 // epilogue. Once the MachineFunction is ready, it is assembled for TM to
  51 // AsmStream, the temporary function is eventually discarded.
  52 void assembleToStream(const ExegesisTarget &ET,
  53                       std::unique_ptr<llvm::LLVMTargetMachine> TM,
  54                       llvm::ArrayRef<unsigned> LiveIns,
  55                       llvm::ArrayRef<RegisterValue> RegisterInitialValues,
  56                       llvm::ArrayRef<llvm::MCInst> Instructions,
  57                       llvm::raw_pwrite_stream &AsmStream);
  58
  59 // Creates an ObjectFile in the format understood by the host.
  60 // Note: the resulting object keeps a copy of Buffer so it can be discarded once
  61 // this function returns.
  62 llvm::object::OwningBinary<llvm::object::ObjectFile>
  63 getObjectFromBuffer(llvm::StringRef Buffer);
  64
  65 // Loads the content of Filename as on ObjectFile and returns it.
  66 llvm::object::OwningBinary<llvm::object::ObjectFile>
  67 getObjectFromFile(llvm::StringRef Filename);
  68
  69 // Consumes an ObjectFile containing a `void foo(char*)` function and make it
  70 // executable.
  71 struct ExecutableFunction {
  72   explicit ExecutableFunction(
  73       std::unique_ptr<llvm::LLVMTargetMachine> TM,
  74       llvm::object::OwningBinary<llvm::object::ObjectFile> &&ObjectFileHolder);
  75
  76   // Retrieves the function as an array of bytes.
  77   llvm::StringRef getFunctionBytes() const { return FunctionBytes; }
  78
  79   // Executes the function.
  80   void operator()(char *Memory) const {
  81     ((void (*)(char *))(intptr_t)FunctionBytes.data())(Memory);
  82   }
  83
  84   std::unique_ptr<llvm::LLVMContext> Context;
  85   std::unique_ptr<llvm::ExecutionEngine> ExecEngine;
  86   llvm::StringRef FunctionBytes;
  87 };
  88
  89 } // namespace exegesis
  90
  91 #endif // LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H