LLVM  10.0.0svn
R600FrameLowering.cpp
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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"
15 
16 using namespace llvm;
17 
19 
20 /// \returns The number of registers allocated for \p FI.
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 }
Register getFrameRegister(const MachineFunction &MF) const override
AMDGPU specific subclass of TargetSubtarget.
This class represents lattice values for constants.
Definition: AllocatorList.h:23
unsigned getNumObjects() const
Return the number of objects.
Interface definition for R600RegisterInfo.
int getFrameIndexReference(const MachineFunction &MF, int FI, unsigned &FrameReg) const override
The MachineFrameInfo class represents an abstract stack frame until prolog/epilog code is inserted...
int getObjectIndexBegin() const
Return the minimum frame object index.
int64_t getObjectSize(int ObjectIdx) const
Return the size of the specified object.
unsigned getObjectAlignment(int ObjectIdx) const
Return the alignment of the specified stack object.
~R600FrameLowering() override
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
MachineFrameInfo & getFrameInfo()
getFrameInfo - Return the frame info object for the current function.
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
Definition: Alignment.h:163
unsigned getStackWidth(const MachineFunction &MF) const