1//===-- LoongArchSubtarget.cpp - LoongArch Subtarget Information -*- C++ -*--=//
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// This file implements the LoongArch specific subclass of TargetSubtargetInfo.
10//
11//===----------------------------------------------------------------------===//
12
13#include "LoongArchSubtarget.h"
14#include "LoongArchFrameLowering.h"
15#include "LoongArchSelectionDAGInfo.h"
16#include "MCTargetDesc/LoongArchBaseInfo.h"
17
18using namespace llvm;
19
20#define DEBUG_TYPE "loongarch-subtarget"
21
22#define GET_SUBTARGETINFO_TARGET_DESC
23#define GET_SUBTARGETINFO_CTOR
24#include "LoongArchGenSubtargetInfo.inc"
25
26static cl::opt<bool> UseAA("loongarch-use-aa", cl::init(Val: true),
27 cl::desc("Enable the use of AA during codegen."));
28
29void LoongArchSubtarget::anchor() {}
30
31// Enable use of alias analysis during code generation (during MI scheduling,
32// DAGCombine, etc.).
33bool LoongArchSubtarget::useAA() const { return UseAA; }
34
35LoongArchSubtarget &LoongArchSubtarget::initializeSubtargetDependencies(
36 const Triple &TT, StringRef CPU, StringRef TuneCPU, StringRef FS,
37 StringRef ABIName) {
38 bool Is64Bit = TT.isArch64Bit();
39 if (CPU.empty() || CPU == "generic")
40 CPU = Is64Bit ? "generic-la64" : "generic-la32";
41
42 if (TuneCPU.empty())
43 TuneCPU = CPU;
44
45 ParseSubtargetFeatures(CPU, TuneCPU, FS);
46 initializeProperties(TuneCPU);
47 if (Is64Bit) {
48 GRLenVT = MVT::i64;
49 GRLen = 64;
50 }
51
52 if (HasLA32 == HasLA64)
53 report_fatal_error(reason: "Please use one feature of 32bit and 64bit.");
54
55 if (Is64Bit && HasLA32)
56 report_fatal_error(reason: "Feature 32bit should be used for loongarch32 target.");
57
58 if (!Is64Bit && HasLA64)
59 report_fatal_error(reason: "Feature 64bit should be used for loongarch64 target.");
60
61 TargetABI = LoongArchABI::computeTargetABI(TT, FeatureBits: getFeatureBits(), ABIName);
62
63 return *this;
64}
65
66void LoongArchSubtarget::initializeProperties(StringRef TuneCPU) {
67 // Initialize CPU specific properties. We should add a tablegen feature for
68 // this in the future so we can specify it together with the subtarget
69 // features.
70
71 // TODO: Check TuneCPU and override defaults (that are for LA464) once we
72 // support optimizing for more uarchs.
73
74 // Default to the alignment settings empirically confirmed to perform best
75 // on LA464, with 4-wide instruction fetch and decode stages. These settings
76 // can also be overridden in initializeProperties.
77 //
78 // We default to such higher-than-minimum alignments because we assume that:
79 //
80 // * these settings should benefit most existing uarchs/users,
81 // * future general-purpose LoongArch cores are likely to have issue widths
82 // equal to or wider than 4,
83 // * instruction sequences best for LA464 should not pessimize other future
84 // uarchs, and
85 // * narrower cores would not suffer much (aside from slightly increased
86 // ICache footprint maybe), compared to the gains everywhere else.
87 PrefFunctionAlignment = Align(32);
88 PrefLoopAlignment = Align(16);
89 MaxBytesForAlignment = 16;
90}
91
92LoongArchSubtarget::LoongArchSubtarget(const Triple &TT, StringRef CPU,
93 StringRef TuneCPU, StringRef FS,
94 StringRef ABIName,
95 const TargetMachine &TM)
96 : LoongArchGenSubtargetInfo(TT, CPU, TuneCPU, FS),
97 FrameLowering(
98 initializeSubtargetDependencies(TT, CPU, TuneCPU, FS, ABIName)),
99 InstrInfo(*this), TLInfo(TM, *this) {
100 TSInfo = std::make_unique<LoongArchSelectionDAGInfo>();
101}
102
103LoongArchSubtarget::~LoongArchSubtarget() = default;
104
105const SelectionDAGTargetInfo *LoongArchSubtarget::getSelectionDAGInfo() const {
106 return TSInfo.get();
107}
108