Separate X86ISelLowering stuff out from the X86ISelPattern.cpp file.  Patch
contributed by Evan Cheng.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24358 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
new file mode 100644
index 0000000..b4468ac
--- /dev/null
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -0,0 +1,131 @@
+//===-- X86ISelLowering.h - X86 DAG Lowering Interface ----------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the interfaces that X86 uses to lower LLVM code into a
+// selection DAG.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef X86ISELLOWERING_H
+#define X86ISELLOWERING_H
+
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+
+namespace llvm {
+  // X86 Specific DAG Nodes
+  namespace X86ISD {
+    enum NodeType {
+      // Start the numbering where the builtin ops leave off.
+      FIRST_NUMBER = ISD::BUILTIN_OP_END,
+
+      /// FILD64m - This instruction implements SINT_TO_FP with a
+      /// 64-bit source in memory and a FP reg result.  This corresponds to
+      /// the X86::FILD64m instruction.  It has two inputs (token chain and
+      /// address) and two outputs (FP value and token chain).
+      FILD64m,
+
+      /// FP_TO_INT*_IN_MEM - This instruction implements FP_TO_SINT with the
+      /// integer destination in memory and a FP reg source.  This corresponds
+      /// to the X86::FIST*m instructions and the rounding mode change stuff. It
+      /// has two inputs (token chain and address) and two outputs (FP value and
+      /// token chain).
+      FP_TO_INT16_IN_MEM,
+      FP_TO_INT32_IN_MEM,
+      FP_TO_INT64_IN_MEM,
+
+      /// CALL/TAILCALL - These operations represent an abstract X86 call
+      /// instruction, which includes a bunch of information.  In particular the
+      /// operands of these node are:
+      ///
+      ///     #0 - The incoming token chain
+      ///     #1 - The callee
+      ///     #2 - The number of arg bytes the caller pushes on the stack.
+      ///     #3 - The number of arg bytes the callee pops off the stack.
+      ///     #4 - The value to pass in AL/AX/EAX (optional)
+      ///     #5 - The value to pass in DL/DX/EDX (optional)
+      ///
+      /// The result values of these nodes are:
+      ///
+      ///     #0 - The outgoing token chain
+      ///     #1 - The first register result value (optional)
+      ///     #2 - The second register result value (optional)
+      ///
+      /// The CALL vs TAILCALL distinction boils down to whether the callee is
+      /// known not to modify the caller's stack frame, as is standard with
+      /// LLVM.
+      CALL,
+      TAILCALL,
+    };
+  }
+
+  //===----------------------------------------------------------------------===//
+  //  X86TargetLowering - X86 Implementation of the TargetLowering interface
+  class X86TargetLowering : public TargetLowering {
+    int VarArgsFrameIndex;            // FrameIndex for start of varargs area.
+    int ReturnAddrIndex;              // FrameIndex for return slot.
+    int BytesToPopOnReturn;           // Number of arg bytes ret should pop.
+    int BytesCallerReserves;          // Number of arg bytes caller makes.
+  public:
+    X86TargetLowering(TargetMachine &TM);
+
+    // Return the number of bytes that a function should pop when it returns (in
+    // addition to the space used by the return address).
+    //
+    unsigned getBytesToPopOnReturn() const { return BytesToPopOnReturn; }
+
+    // Return the number of bytes that the caller reserves for arguments passed
+    // to this function.
+    unsigned getBytesCallerReserves() const { return BytesCallerReserves; }
+ 
+    /// LowerOperation - Provide custom lowering hooks for some operations.
+    ///
+    virtual SDOperand LowerOperation(SDOperand Op, SelectionDAG &DAG);
+
+    /// LowerArguments - This hook must be implemented to indicate how we should
+    /// lower the arguments for the specified function, into the specified DAG.
+    virtual std::vector<SDOperand>
+    LowerArguments(Function &F, SelectionDAG &DAG);
+
+    /// LowerCallTo - This hook lowers an abstract call to a function into an
+    /// actual call.
+    virtual std::pair<SDOperand, SDOperand>
+    LowerCallTo(SDOperand Chain, const Type *RetTy, bool isVarArg, unsigned CC,
+                bool isTailCall, SDOperand Callee, ArgListTy &Args,
+                SelectionDAG &DAG);
+
+    virtual SDOperand LowerVAStart(SDOperand Chain, SDOperand VAListP,
+                                   Value *VAListV, SelectionDAG &DAG);
+    virtual std::pair<SDOperand,SDOperand>
+    LowerVAArg(SDOperand Chain, SDOperand VAListP, Value *VAListV,
+               const Type *ArgTy, SelectionDAG &DAG);
+
+    virtual std::pair<SDOperand, SDOperand>
+    LowerFrameReturnAddress(bool isFrameAddr, SDOperand Chain, unsigned Depth,
+                            SelectionDAG &DAG);
+
+    SDOperand getReturnAddressFrameIndex(SelectionDAG &DAG);
+
+  private:
+    // C Calling Convention implementation.
+    std::vector<SDOperand> LowerCCCArguments(Function &F, SelectionDAG &DAG);
+    std::pair<SDOperand, SDOperand>
+    LowerCCCCallTo(SDOperand Chain, const Type *RetTy, bool isVarArg,
+                   bool isTailCall,
+                   SDOperand Callee, ArgListTy &Args, SelectionDAG &DAG);
+
+    // Fast Calling Convention implementation.
+    std::vector<SDOperand> LowerFastCCArguments(Function &F, SelectionDAG &DAG);
+    std::pair<SDOperand, SDOperand>
+    LowerFastCCCallTo(SDOperand Chain, const Type *RetTy, bool isTailCall,
+                      SDOperand Callee, ArgListTy &Args, SelectionDAG &DAG);
+  };
+}
+
+#endif    // X86ISELLOWERING_H