1 //===----------------------- AMDGPUFrameLowering.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 // Interface to describe a layout of a stack frame on a AMDGPU target machine.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "AMDGPUFrameLowering.h"
15
16 using namespace llvm;
AMDGPUFrameLowering(StackDirection D,unsigned StackAl,int LAO,unsigned TransAl)17 AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, unsigned StackAl,
18 int LAO, unsigned TransAl)
19 : TargetFrameLowering(D, StackAl, LAO, TransAl) { }
20
21 AMDGPUFrameLowering::~AMDGPUFrameLowering() = default;
22
getStackWidth(const MachineFunction & MF) const23 unsigned AMDGPUFrameLowering::getStackWidth(const MachineFunction &MF) const {
24 // XXX: Hardcoding to 1 for now.
25 //
26 // I think the StackWidth should stored as metadata associated with the
27 // MachineFunction. This metadata can either be added by a frontend, or
28 // calculated by a R600 specific LLVM IR pass.
29 //
30 // The StackWidth determines how stack objects are laid out in memory.
31 // For a vector stack variable, like: int4 stack[2], the data will be stored
32 // in the following ways depending on the StackWidth.
33 //
34 // StackWidth = 1:
35 //
36 // T0.X = stack[0].x
37 // T1.X = stack[0].y
38 // T2.X = stack[0].z
39 // T3.X = stack[0].w
40 // T4.X = stack[1].x
41 // T5.X = stack[1].y
42 // T6.X = stack[1].z
43 // T7.X = stack[1].w
44 //
45 // StackWidth = 2:
46 //
47 // T0.X = stack[0].x
48 // T0.Y = stack[0].y
49 // T1.X = stack[0].z
50 // T1.Y = stack[0].w
51 // T2.X = stack[1].x
52 // T2.Y = stack[1].y
53 // T3.X = stack[1].z
54 // T3.Y = stack[1].w
55 //
56 // StackWidth = 4:
57 // T0.X = stack[0].x
58 // T0.Y = stack[0].y
59 // T0.Z = stack[0].z
60 // T0.W = stack[0].w
61 // T1.X = stack[1].x
62 // T1.Y = stack[1].y
63 // T1.Z = stack[1].z
64 // T1.W = stack[1].w
65 return 1;
66 }
67