tools/llvm-exegesis/lib/Assembler.h

   1 //===-- Assembler.h ---------------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 ///
   9 /// \file
  10 /// Defines classes to assemble functions composed of a single basic block of
  11 /// MCInsts.
  12 ///
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H
  16 #define LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H
  17
  18 #include <memory>
  19
  20 #include "BenchmarkCode.h"
  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 llvm {
  35 namespace exegesis {
  36
  37 class ExegesisTarget;
  38
  39 // Gather the set of reserved registers (depends on function's calling
  40 // convention and target machine).
  41 BitVector getFunctionReservedRegs(const TargetMachine &TM);
  42
  43 // Helper to fill in a basic block.
  44 class BasicBlockFiller {
  45 public:
  46   BasicBlockFiller(MachineFunction &MF, MachineBasicBlock *MBB,
  47                    const MCInstrInfo *MCII);
  48
  49   void addInstruction(const MCInst &Inst, const DebugLoc &DL = DebugLoc());
  50   void addInstructions(ArrayRef<MCInst> Insts, const DebugLoc &DL = DebugLoc());
  51
  52   void addReturn(const DebugLoc &DL = DebugLoc());
  53
  54   MachineFunction &MF;
  55   MachineBasicBlock *const MBB;
  56   const MCInstrInfo *const MCII;
  57 };
  58
  59 // Helper to fill in a function.
  60 class FunctionFiller {
  61 public:
  62   FunctionFiller(MachineFunction &MF, std::vector<unsigned> RegistersSetUp);
  63
  64   // Adds a basic block to the function.
  65   BasicBlockFiller addBasicBlock();
  66
  67   // Returns the function entry point.
  68   BasicBlockFiller getEntry() { return Entry; }
  69
  70   MachineFunction &MF;
  71   const MCInstrInfo *const MCII;
  72
  73   // Returns the set of registers in the snippet setup code.
  74   ArrayRef<unsigned> getRegistersSetUp() const;
  75
  76 private:
  77   BasicBlockFiller Entry;
  78   // The set of registers that are set up in the basic block.
  79   std::vector<unsigned> RegistersSetUp;
  80 };
  81
  82 // A callback that fills a function.
  83 using FillFunction = std::function<void(FunctionFiller &)>;
  84
  85 // Creates a temporary `void foo(char*)` function containing the provided
  86 // Instructions. Runs a set of llvm Passes to provide correct prologue and
  87 // epilogue. Once the MachineFunction is ready, it is assembled for TM to
  88 // AsmStream, the temporary function is eventually discarded.
  89 void assembleToStream(const ExegesisTarget &ET,
  90                       std::unique_ptr<LLVMTargetMachine> TM,
  91                       ArrayRef<unsigned> LiveIns,
  92                       ArrayRef<RegisterValue> RegisterInitialValues,
  93                       const FillFunction &Fill, raw_pwrite_stream &AsmStream);
  94
  95 // Creates an ObjectFile in the format understood by the host.
  96 // Note: the resulting object keeps a copy of Buffer so it can be discarded once
  97 // this function returns.
  98 object::OwningBinary<object::ObjectFile> getObjectFromBuffer(StringRef Buffer);
  99
 100 // Loads the content of Filename as on ObjectFile and returns it.
 101 object::OwningBinary<object::ObjectFile> getObjectFromFile(StringRef Filename);
 102
 103 // Consumes an ObjectFile containing a `void foo(char*)` function and make it
 104 // executable.
 105 struct ExecutableFunction {
 106   explicit ExecutableFunction(
 107       std::unique_ptr<LLVMTargetMachine> TM,
 108       object::OwningBinary<object::ObjectFile> &&ObjectFileHolder);
 109
 110   // Retrieves the function as an array of bytes.
 111   StringRef getFunctionBytes() const { return FunctionBytes; }
 112
 113   // Executes the function.
 114   void operator()(char *Memory) const {
 115     ((void (*)(char *))(intptr_t)FunctionBytes.data())(Memory);
 116   }
 117
 118   std::unique_ptr<LLVMContext> Context;
 119   std::unique_ptr<ExecutionEngine> ExecEngine;
 120   StringRef FunctionBytes;
 121 };
 122
 123 // Creates a void(int8*) MachineFunction.
 124 MachineFunction &createVoidVoidPtrMachineFunction(StringRef FunctionID,
 125                                                   Module *Module,
 126                                                   MachineModuleInfo *MMI);
 127
 128 } // namespace exegesis
 129 } // namespace llvm
 130
 131 #endif // LLVM_TOOLS_LLVM_EXEGESIS_ASSEMBLER_H