Allow more than one stub to be being generated at the same time.

It's probably better in the long run to replace the
indirect-GlobalVariable system. That'll be done after a subsequent
patch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89708 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 51 insertions, 21 deletions

diff --git a/include/llvm/CodeGen/JITCodeEmitter.h b/include/llvm/CodeGen/JITCodeEmitter.h
index 792fb59923..ea3e59beab 100644
--- a/include/llvm/CodeGen/JITCodeEmitter.h
+++ b/include/llvm/CodeGen/JITCodeEmitter.h
@@ -68,23 +68,29 @@ public:
   ///
   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.
+  /// 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.  The BufferState must be
+  /// passed to finishGVStub, and start/finish pairs with the same BufferState
+  /// must be properly nested.
   ///
-  virtual void startGVStub(const GlobalValue* GV, unsigned StubSize,
-                           unsigned Alignment = 1) = 0;
+  virtual void startGVStub(BufferState &BS, const GlobalValue* GV,
+                           unsigned StubSize, unsigned Alignment = 1) = 0;
 
-  /// startGVStub - This callback is invoked when the JIT needs the address of a 
+  /// 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.
+  /// memory already allocated for this stub.  The BufferState must be passed to
+  /// finishGVStub, and start/finish pairs with the same BufferState must be
+  /// properly nested.
   ///
-  virtual void startGVStub(const GlobalValue* GV, void *Buffer,
+  virtual void startGVStub(BufferState &BS, void *Buffer,
                            unsigned StubSize) = 0;
-  
-  /// finishGVStub - This callback is invoked to terminate a GV stub.
+
+  /// finishGVStub - This callback is invoked to terminate a GV stub and returns
+  /// the start address of the stub.  The BufferState must first have been
+  /// passed to startGVStub.
   ///
-  virtual void *finishGVStub(const GlobalValue* F) = 0;
+  virtual void *finishGVStub(BufferState &BS) = 0;
 
   /// emitByte - This callback is invoked when a byte needs to be written to the
   /// output stream.
diff --git a/include/llvm/CodeGen/MachineCodeEmitter.h b/include/llvm/CodeGen/MachineCodeEmitter.h
index c55a9e65e4..791db003ea 100644
--- a/include/llvm/CodeGen/MachineCodeEmitter.h
+++ b/include/llvm/CodeGen/MachineCodeEmitter.h
@@ -48,17 +48,41 @@ class Function;
 /// occurred, more memory is allocated, and we reemit the code into it.
 /// 
 class MachineCodeEmitter {
+public:
+  class BufferState {
+    friend class MachineCodeEmitter;
+    /// BufferBegin/BufferEnd - Pointers to the start and end of the memory
+    /// allocated for this code buffer.
+    uint8_t *BufferBegin, *BufferEnd;
+
+    /// CurBufferPtr - Pointer to the next byte of memory to fill when emitting
+    /// code.  This is guranteed to be in the range [BufferBegin,BufferEnd].  If
+    /// this pointer is at BufferEnd, it will never move due to code emission,
+    /// and all code emission requests will be ignored (this is the buffer
+    /// overflow condition).
+    uint8_t *CurBufferPtr;
+  public:
+    BufferState() : BufferBegin(NULL), BufferEnd(NULL), CurBufferPtr(NULL) {}
+  };
+
 protected:
-  /// BufferBegin/BufferEnd - Pointers to the start and end of the memory
-  /// allocated for this code buffer.
-  uint8_t *BufferBegin, *BufferEnd;
-  
-  /// CurBufferPtr - Pointer to the next byte of memory to fill when emitting 
-  /// code.  This is guranteed to be in the range [BufferBegin,BufferEnd].  If
-  /// this pointer is at BufferEnd, it will never move due to code emission, and
-  /// all code emission requests will be ignored (this is the buffer overflow
-  /// condition).
-  uint8_t *CurBufferPtr;
+  /// These have the same meanings as the fields in BufferState
+  uint8_t *BufferBegin, *BufferEnd, *CurBufferPtr;
+
+  /// Save or restore the current buffer state.  The BufferState objects must be
+  /// used as a stack.
+  void SaveStateTo(BufferState &BS) {
+    assert(BS.BufferBegin == NULL &&
+           "Can't save state into the same BufferState twice.");
+    BS.BufferBegin = BufferBegin;
+    BS.BufferEnd = BufferEnd;
+    BS.CurBufferPtr = CurBufferPtr;
+  }
+  void RestoreStateFrom(BufferState &BS) {
+    BufferBegin = BS.BufferBegin;
+    BufferEnd = BS.BufferEnd;
+    CurBufferPtr = BS.CurBufferPtr;
+  }
 
 public:
   virtual ~MachineCodeEmitter() {}