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
16using namespace llvm;
17
18R600FrameLowering::~R600FrameLowering() = default;
19
20/// \returns The number of registers allocated for \p FI.
21int 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}
50