66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
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//===----------------------- AMDGPUFrameLowering.cpp ----------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//==-----------------------------------------------------------------------===//
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//
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// Interface to describe a layout of a stack frame on a AMDGPU target machine.
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//
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//===----------------------------------------------------------------------===//
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#include "AMDGPUFrameLowering.h"
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using namespace llvm;
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AMDGPUFrameLowering::AMDGPUFrameLowering(StackDirection D, Align StackAl,
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int LAO, Align TransAl)
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: TargetFrameLowering(D, StackAl, LAO, TransAl) {}
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AMDGPUFrameLowering::~AMDGPUFrameLowering() = default;
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unsigned AMDGPUFrameLowering::getStackWidth(const MachineFunction &MF) const {
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// XXX: Hardcoding to 1 for now.
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//
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// I think the StackWidth should stored as metadata associated with the
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// MachineFunction. This metadata can either be added by a frontend, or
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// calculated by a R600 specific LLVM IR pass.
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//
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// The StackWidth determines how stack objects are laid out in memory.
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// For a vector stack variable, like: int4 stack[2], the data will be stored
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// in the following ways depending on the StackWidth.
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//
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// StackWidth = 1:
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//
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// T0.X = stack[0].x
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// T1.X = stack[0].y
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// T2.X = stack[0].z
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// T3.X = stack[0].w
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// T4.X = stack[1].x
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// T5.X = stack[1].y
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// T6.X = stack[1].z
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// T7.X = stack[1].w
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//
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// StackWidth = 2:
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//
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// T0.X = stack[0].x
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// T0.Y = stack[0].y
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// T1.X = stack[0].z
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// T1.Y = stack[0].w
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// T2.X = stack[1].x
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// T2.Y = stack[1].y
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// T3.X = stack[1].z
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// T3.Y = stack[1].w
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//
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// StackWidth = 4:
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// T0.X = stack[0].x
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// T0.Y = stack[0].y
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// T0.Z = stack[0].z
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// T0.W = stack[0].w
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// T1.X = stack[1].x
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// T1.Y = stack[1].y
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// T1.Z = stack[1].z
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// T1.W = stack[1].w
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return 1;
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}
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