path: root/lib/Target/X86/X86FloatingPoint.cpp

//===-- X86FloatingPoint.cpp - Floating point Reg -> Stack converter ------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the pass which converts floating point instructions from
// pseudo registers into register stack instructions.  This pass uses live
// variable information to indicate where the FPn registers are used and their
// lifetimes.
//
// The x87 hardware tracks liveness of the stack registers, so it is necessary
// to implement exact liveness tracking between basic blocks. The CFG edges are
// partitioned into bundles where the same FP registers must be live in
// identical stack positions. Instructions are inserted at the end of each basic
// block to rearrange the live registers to match the outgoing bundle.
//
// This approach avoids splitting critical edges at the potential cost of more
// live register shuffling instructions when critical edges are present.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "x86-codegen"
#include "X86.h"
#include "X86InstrInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"