lib/Target/AMDGPU/R600FrameLowering.cpp

   1 //===----------------------- R600FrameLowering.cpp ------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //==-----------------------------------------------------------------------===//
   8
   9 #include "R600FrameLowering.h"
  10 #include "AMDGPUSubtarget.h"
  11 #include "R600RegisterInfo.h"
  12 #include "llvm/CodeGen/MachineFrameInfo.h"
  13 #include "llvm/CodeGen/MachineFunction.h"
  14 #include "llvm/Support/MathExtras.h"
  15
  16 using namespace llvm;
  17
  18 R600FrameLowering::~R600FrameLowering() = default;
  19
  20 /// \returns The number of registers allocated for \p FI.
  21 int R600FrameLowering::getFrameIndexReference(const MachineFunction &MF,
  22                                               int FI,
  23                                               unsigned &FrameReg) const {
  24   const MachineFrameInfo &MFI = MF.getFrameInfo();
  25   const R600RegisterInfo *RI
  26     = MF.getSubtarget<R600Subtarget>().getRegisterInfo();
  27
  28   // Fill in FrameReg output argument.
  29   FrameReg = RI->getFrameRegister(MF);
  30
  31   // Start the offset at 2 so we don't overwrite work group information.
  32   // FIXME: We should only do this when the shader actually uses this
  33   // information.
  34   unsigned OffsetBytes = 2 * (getStackWidth(MF) * 4);
  35   int UpperBound = FI == -1 ? MFI.getNumObjects() : FI;
  36
  37   for (int i = MFI.getObjectIndexBegin(); i < UpperBound; ++i) {
  38     OffsetBytes = alignTo(OffsetBytes, MFI.getObjectAlignment(i));
  39     OffsetBytes += MFI.getObjectSize(i);
  40     // Each register holds 4 bytes, so we must always align the offset to at
  41     // least 4 bytes, so that 2 frame objects won't share the same register.
  42     OffsetBytes = alignTo(OffsetBytes, 4);
  43   }
  44
  45   if (FI != -1)
  46     OffsetBytes = alignTo(OffsetBytes, MFI.getObjectAlignment(FI));
  47
  48   return OffsetBytes / (getStackWidth(MF) * 4);
  49 }