1 //===----------------------- AMDGPUFrameLowering.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 // Interface to describe a layout of a stack frame on a AMDGPU target machine. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "AMDGPUFrameLowering.h" 14 15 using namespace llvm; 16 AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, Align StackAl, 17 int LAO, Align TransAl) 18 : TargetFrameLowering(D, StackAl, LAO, TransAl) {} 19 20 AMDGPUFrameLowering::~AMDGPUFrameLowering() = default; 21 22 unsigned AMDGPUFrameLowering::getStackWidth(const MachineFunction &MF) const { 23 // XXX: Hardcoding to 1 for now. 24 // 25 // I think the StackWidth should stored as metadata associated with the 26 // MachineFunction. This metadata can either be added by a frontend, or 27 // calculated by a R600 specific LLVM IR pass. 28 // 29 // The StackWidth determines how stack objects are laid out in memory. 30 // For a vector stack variable, like: int4 stack[2], the data will be stored 31 // in the following ways depending on the StackWidth. 32 // 33 // StackWidth = 1: 34 // 35 // T0.X = stack[0].x 36 // T1.X = stack[0].y 37 // T2.X = stack[0].z 38 // T3.X = stack[0].w 39 // T4.X = stack[1].x 40 // T5.X = stack[1].y 41 // T6.X = stack[1].z 42 // T7.X = stack[1].w 43 // 44 // StackWidth = 2: 45 // 46 // T0.X = stack[0].x 47 // T0.Y = stack[0].y 48 // T1.X = stack[0].z 49 // T1.Y = stack[0].w 50 // T2.X = stack[1].x 51 // T2.Y = stack[1].y 52 // T3.X = stack[1].z 53 // T3.Y = stack[1].w 54 // 55 // StackWidth = 4: 56 // T0.X = stack[0].x 57 // T0.Y = stack[0].y 58 // T0.Z = stack[0].z 59 // T0.W = stack[0].w 60 // T1.X = stack[1].x 61 // T1.Y = stack[1].y 62 // T1.Z = stack[1].z 63 // T1.W = stack[1].w 64 return 1; 65 } 66