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.
getFrameIndexReference(const MachineFunction & MF,int FI,unsigned & FrameReg) const21 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 }
50