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; 17 AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, unsigned StackAl, 18 int LAO, unsigned TransAl) 19 : TargetFrameLowering(D, StackAl, LAO, TransAl) { } 20 21 AMDGPUFrameLowering::~AMDGPUFrameLowering() = default; 22 23 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