lib/Target/AMDGPU/R600FrameLowering.cpp

   1 //===----------------------- R600FrameLowering.cpp ------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //==-----------------------------------------------------------------------===//
   9
  10 #include "R600FrameLowering.h"
  11 #include "AMDGPUSubtarget.h"
  12 #include "R600RegisterInfo.h"
  13 #include "llvm/CodeGen/MachineFrameInfo.h"
  14 #include "llvm/CodeGen/MachineFunction.h"
  15 #include "llvm/Support/MathExtras.h"
  16
  17 using namespace llvm;
  18
  19 R600FrameLowering::~R600FrameLowering() = default;
  20
  21 /// \returns The number of registers allocated for \p FI.
  22 int R600FrameLowering::getFrameIndexReference(const MachineFunction &MF,
  23                                               int FI,
  24                                               unsigned &FrameReg) const {
  25   const MachineFrameInfo &MFI = MF.getFrameInfo();
  26   const R600RegisterInfo *RI
  27     = MF.getSubtarget<R600Subtarget>().getRegisterInfo();
  28
  29   // Fill in FrameReg output argument.
  30   FrameReg = RI->getFrameRegister(MF);
  31
  32   // Start the offset at 2 so we don't overwrite work group information.
  33   // FIXME: We should only do this when the shader actually uses this
  34   // information.
  35   unsigned OffsetBytes = 2 * (getStackWidth(MF) * 4);
  36   int UpperBound = FI == -1 ? MFI.getNumObjects() : FI;
  37
  38   for (int i = MFI.getObjectIndexBegin(); i < UpperBound; ++i) {
  39     OffsetBytes = alignTo(OffsetBytes, MFI.getObjectAlignment(i));
  40     OffsetBytes += MFI.getObjectSize(i);
  41     // Each register holds 4 bytes, so we must always align the offset to at
  42     // least 4 bytes, so that 2 frame objects won't share the same register.
  43     OffsetBytes = alignTo(OffsetBytes, 4);
  44   }
  45
  46   if (FI != -1)
  47     OffsetBytes = alignTo(OffsetBytes, MFI.getObjectAlignment(FI));
  48
  49   return OffsetBytes / (getStackWidth(MF) * 4);
  50 }