First patch in the direction of splitting MachineCodeEmitter in two subclasses:

JITCodeEmitter and ObjectCodeEmitter. No functional changes yet. Patch by Aaron Gray



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72631 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 322 insertions, 0 deletions

diff --git a/include/llvm/CodeGen/JITCodeEmitter.h b/include/llvm/CodeGen/JITCodeEmitter.h
new file mode 100644
index 0000000000..81a7c60bdb
--- /dev/null
+++ b/include/llvm/CodeGen/JITCodeEmitter.h
@@ -0,0 +1,322 @@
+//===-- llvm/CodeGen/JITCodeEmitter.h - Code emission ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines an abstract interface that is used by the machine code
+// emission framework to output the code.  This allows machine code emission to
+// be separated from concerns such as resolution of call targets, and where the
+// machine code will be written (memory or disk, f.e.).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_JITCODEEMITTER_H
+#define LLVM_CODEGEN_JITCODEEMITTER_H
+
+#include <string>
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/CodeGen/MachineCodeEmitter.h"
+
+using namespace std;
+
+namespace llvm {
+
+class MachineBasicBlock;
+class MachineConstantPool;
+class MachineJumpTableInfo;
+class MachineFunction;
+class MachineModuleInfo;
+class MachineRelocation;
+class Value;
+class GlobalValue;
+class Function;
+
+/// JITCodeEmitter - This class defines two sorts of methods: those for
+/// emitting the actual bytes of machine code, and those for emitting auxillary
+/// structures, such as jump tables, relocations, etc.
+///
+/// Emission of machine code is complicated by the fact that we don't (in
+/// general) know the size of the machine code that we're about to emit before
+/// we emit it.  As such, we preallocate a certain amount of memory, and set the
+/// BufferBegin/BufferEnd pointers to the start and end of the buffer.  As we
+/// emit machine instructions, we advance the CurBufferPtr to indicate the
+/// location of the next byte to emit.  In the case of a buffer overflow (we
+/// need to emit more machine code than we have allocated space for), the
+/// CurBufferPtr will saturate to BufferEnd and ignore stores.  Once the entire
+/// function has been emitted, the overflow condition is checked, and if it has
+/// occurred, more memory is allocated, and we reemit the code into it.
+/// 
+class JITCodeEmitter : public MachineCodeEmitter {
+public:
+  virtual ~JITCodeEmitter() {}
+
+  /// startFunction - This callback is invoked when the specified function is
+  /// about to be code generated.  This initializes the BufferBegin/End/Ptr
+  /// fields.
+  ///
+  virtual void startFunction(MachineFunction &F) = 0;
+
+  /// finishFunction - This callback is invoked when the specified function has
+  /// finished code generation.  If a buffer overflow has occurred, this method
+  /// returns true (the callee is required to try again), otherwise it returns
+  /// false.
+  ///
+  virtual bool finishFunction(MachineFunction &F) = 0;
+  
+  /// startGVStub - This callback is invoked when the JIT needs the
+  /// address of a GV (e.g. function) that has not been code generated yet.
+  /// The StubSize specifies the total size required by the stub.
+  ///
+  virtual void startGVStub(const GlobalValue* GV, unsigned StubSize,
+                           unsigned Alignment = 1) = 0;
+
+  /// startGVStub - This callback is invoked when the JIT needs the address of a 
+  /// GV (e.g. function) that has not been code generated yet.  Buffer points to
+  /// memory already allocated for this stub.
+  ///
+  virtual void startGVStub(const GlobalValue* GV, void *Buffer,
+                           unsigned StubSize) = 0;
+  
+  /// finishGVStub - This callback is invoked to terminate a GV stub.
+  ///
+  virtual void *finishGVStub(const GlobalValue* F) = 0;
+
+  /// emitByte - This callback is invoked when a byte needs to be written to the
+  /// output stream.
+  ///
+  void emitByte(unsigned char B) {
+    if (CurBufferPtr != BufferEnd)
+      *CurBufferPtr++ = B;
+  }
+
+  /// emitWordLE - This callback is invoked when a 32-bit word needs to be
+  /// written to the output stream in little-endian format.
+  ///
+  void emitWordLE(unsigned W) {
+    if (4 <= BufferEnd-CurBufferPtr) {
+      *CurBufferPtr++ = (unsigned char)(W >>  0);
+      *CurBufferPtr++ = (unsigned char)(W >>  8);
+      *CurBufferPtr++ = (unsigned char)(W >> 16);
+      *CurBufferPtr++ = (unsigned char)(W >> 24);
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+  
+  /// emitWordBE - This callback is invoked when a 32-bit word needs to be
+  /// written to the output stream in big-endian format.
+  ///
+  void emitWordBE(unsigned W) {
+    if (4 <= BufferEnd-CurBufferPtr) {
+      *CurBufferPtr++ = (unsigned char)(W >> 24);
+      *CurBufferPtr++ = (unsigned char)(W >> 16);
+      *CurBufferPtr++ = (unsigned char)(W >>  8);
+      *CurBufferPtr++ = (unsigned char)(W >>  0);
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+
+  /// emitDWordLE - This callback is invoked when a 64-bit word needs to be
+  /// written to the output stream in little-endian format.
+  ///
+  void emitDWordLE(uint64_t W) {
+    if (8 <= BufferEnd-CurBufferPtr) {
+      *CurBufferPtr++ = (unsigned char)(W >>  0);
+      *CurBufferPtr++ = (unsigned char)(W >>  8);
+      *CurBufferPtr++ = (unsigned char)(W >> 16);
+      *CurBufferPtr++ = (unsigned char)(W >> 24);
+      *CurBufferPtr++ = (unsigned char)(W >> 32);
+      *CurBufferPtr++ = (unsigned char)(W >> 40);
+      *CurBufferPtr++ = (unsigned char)(W >> 48);
+      *CurBufferPtr++ = (unsigned char)(W >> 56);
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+  
+  /// emitDWordBE - This callback is invoked when a 64-bit word needs to be
+  /// written to the output stream in big-endian format.
+  ///
+  void emitDWordBE(uint64_t W) {
+    if (8 <= BufferEnd-CurBufferPtr) {
+      *CurBufferPtr++ = (unsigned char)(W >> 56);
+      *CurBufferPtr++ = (unsigned char)(W >> 48);
+      *CurBufferPtr++ = (unsigned char)(W >> 40);
+      *CurBufferPtr++ = (unsigned char)(W >> 32);
+      *CurBufferPtr++ = (unsigned char)(W >> 24);
+      *CurBufferPtr++ = (unsigned char)(W >> 16);
+      *CurBufferPtr++ = (unsigned char)(W >>  8);
+      *CurBufferPtr++ = (unsigned char)(W >>  0);
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+
+  /// emitAlignment - Move the CurBufferPtr pointer up the the specified
+  /// alignment (saturated to BufferEnd of course).
+  void emitAlignment(unsigned Alignment) {
+    if (Alignment == 0) Alignment = 1;
+
+    if(Alignment <= (uintptr_t)(BufferEnd-CurBufferPtr)) {
+      // Move the current buffer ptr up to the specified alignment.
+      CurBufferPtr =
+        (unsigned char*)(((uintptr_t)CurBufferPtr+Alignment-1) &
+                         ~(uintptr_t)(Alignment-1));
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+  
+
+  /// emitULEB128Bytes - This callback is invoked when a ULEB128 needs to be
+  /// written to the output stream.
+  void emitULEB128Bytes(unsigned Value) {
+    do {
+      unsigned char Byte = Value & 0x7f;
+      Value >>= 7;
+      if (Value) Byte |= 0x80;
+      emitByte(Byte);
+    } while (Value);
+  }
+  
+  /// emitSLEB128Bytes - This callback is invoked when a SLEB128 needs to be
+  /// written to the output stream.
+  void emitSLEB128Bytes(int Value) {
+    int Sign = Value >> (8 * sizeof(Value) - 1);
+    bool IsMore;
+  
+    do {
+      unsigned char Byte = Value & 0x7f;
+      Value >>= 7;
+      IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
+      if (IsMore) Byte |= 0x80;
+      emitByte(Byte);
+    } while (IsMore);
+  }
+
+  /// emitString - This callback is invoked when a String needs to be
+  /// written to the output stream.
+  void emitString(const std::string &String) {
+    for (unsigned i = 0, N = static_cast<unsigned>(String.size());
+         i < N; ++i) {
+      unsigned char C = String[i];
+      emitByte(C);
+    }
+    emitByte(0);
+  }
+  
+  /// emitInt32 - Emit a int32 directive.
+  void emitInt32(int Value) {
+    if (4 <= BufferEnd-CurBufferPtr) {
+      *((uint32_t*)CurBufferPtr) = Value;
+      CurBufferPtr += 4;
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+
+  /// emitInt64 - Emit a int64 directive.
+  void emitInt64(uint64_t Value) {
+    if (8 <= BufferEnd-CurBufferPtr) {
+      *((uint64_t*)CurBufferPtr) = Value;
+      CurBufferPtr += 8;
+    } else {
+      CurBufferPtr = BufferEnd;
+    }
+  }
+  
+  /// emitInt32At - Emit the Int32 Value in Addr.
+  void emitInt32At(uintptr_t *Addr, uintptr_t Value) {
+    if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd)
+      (*(uint32_t*)Addr) = (uint32_t)Value;
+  }
+  
+  /// emitInt64At - Emit the Int64 Value in Addr.
+  void emitInt64At(uintptr_t *Addr, uintptr_t Value) {
+    if (Addr >= (uintptr_t*)BufferBegin && Addr < (uintptr_t*)BufferEnd)
+      (*(uint64_t*)Addr) = (uint64_t)Value;
+  }
+  
+  
+  /// emitLabel - Emits a label
+  virtual void emitLabel(uint64_t LabelID) = 0;
+
+  /// allocateSpace - Allocate a block of space in the current output buffer,
+  /// returning null (and setting conditions to indicate buffer overflow) on
+  /// failure.  Alignment is the alignment in bytes of the buffer desired.
+  virtual void *allocateSpace(uintptr_t Size, unsigned Alignment) {
+    emitAlignment(Alignment);
+    void *Result;
+    
+    // Check for buffer overflow.
+    if (Size >= (uintptr_t)(BufferEnd-CurBufferPtr)) {
+      CurBufferPtr = BufferEnd;
+      Result = 0;
+    } else {
+      // Allocate the space.
+      Result = CurBufferPtr;
+      CurBufferPtr += Size;
+    }
+    
+    return Result;
+  }
+
+  /// StartMachineBasicBlock - This should be called by the target when a new
+  /// basic block is about to be emitted.  This way the MCE knows where the
+  /// start of the block is, and can implement getMachineBasicBlockAddress.
+  virtual void StartMachineBasicBlock(MachineBasicBlock *MBB) = 0;
+  
+  /// getCurrentPCValue - This returns the address that the next emitted byte
+  /// will be output to.
+  ///
+  virtual uintptr_t getCurrentPCValue() const {
+    return (uintptr_t)CurBufferPtr;
+  }
+
+  /// getCurrentPCOffset - Return the offset from the start of the emitted
+  /// buffer that we are currently writing to.
+  uintptr_t getCurrentPCOffset() const {
+    return CurBufferPtr-BufferBegin;
+  }
+
+  /// addRelocation - Whenever a relocatable address is needed, it should be
+  /// noted with this interface.
+  virtual void addRelocation(const MachineRelocation &MR) = 0;
+  
+  /// FIXME: These should all be handled with relocations!
+  
+  /// getConstantPoolEntryAddress - Return the address of the 'Index' entry in
+  /// the constant pool that was last emitted with the emitConstantPool method.
+  ///
+  virtual uintptr_t getConstantPoolEntryAddress(unsigned Index) const = 0;
+
+  /// getJumpTableEntryAddress - Return the address of the jump table with index
+  /// 'Index' in the function that last called initJumpTableInfo.
+  ///
+  virtual uintptr_t getJumpTableEntryAddress(unsigned Index) const = 0;
+  
+  /// getMachineBasicBlockAddress - Return the address of the specified
+  /// MachineBasicBlock, only usable after the label for the MBB has been
+  /// emitted.
+  ///
+  virtual uintptr_t getMachineBasicBlockAddress(MachineBasicBlock *MBB) const= 0;
+
+  /// getLabelAddress - Return the address of the specified LabelID, only usable
+  /// after the LabelID has been emitted.
+  ///
+  virtual uintptr_t getLabelAddress(uint64_t LabelID) const = 0;
+  
+  /// Specifies the MachineModuleInfo object. This is used for exception handling
+  /// purposes.
+  virtual void setModuleInfo(MachineModuleInfo* Info) = 0;
+};
+
+} // End llvm namespace
+
+#endif