1//===-- PowerPCSubtarget.cpp - PPC Subtarget Information ------------------===//
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 PPC specific subclass of TargetSubtargetInfo.
10//
11//===----------------------------------------------------------------------===//
12
13#include "PPCSubtarget.h"
14#include "GISel/PPCCallLowering.h"
15#include "GISel/PPCLegalizerInfo.h"
16#include "GISel/PPCRegisterBankInfo.h"
17#include "PPC.h"
18#include "PPCRegisterInfo.h"
19#include "PPCSelectionDAGInfo.h"
20#include "PPCTargetMachine.h"
21#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
22#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
23#include "llvm/CodeGen/MachineFunction.h"
24#include "llvm/CodeGen/MachineScheduler.h"
25#include "llvm/IR/GlobalAlias.h"
26#include "llvm/IR/GlobalValue.h"
27#include "llvm/IR/GlobalVariable.h"
28#include "llvm/MC/TargetRegistry.h"
29#include "llvm/Support/CommandLine.h"
30#include "llvm/Target/TargetMachine.h"
31#include "llvm/TargetParser/PPCTargetParser.h"
32#include <cstdlib>
33
34using namespace llvm;
35
36#define DEBUG_TYPE "ppc-subtarget"
37
38#define GET_SUBTARGETINFO_TARGET_DESC
39#define GET_SUBTARGETINFO_CTOR
40#include "PPCGenSubtargetInfo.inc"
41
42static cl::opt<bool>
43 EnableMachinePipeliner("ppc-enable-pipeliner",
44 cl::desc("Enable Machine Pipeliner for PPC"),
45 cl::init(Val: false), cl::Hidden);
46
47PPCSubtarget &PPCSubtarget::initializeSubtargetDependencies(StringRef CPU,
48 StringRef TuneCPU,
49 StringRef FS) {
50 initializeEnvironment();
51 initSubtargetFeatures(CPU, TuneCPU, FS);
52 return *this;
53}
54
55PPCSubtarget::PPCSubtarget(const Triple &TT, const std::string &CPU,
56 const std::string &TuneCPU, const std::string &FS,
57 const PPCTargetMachine &TM)
58 : PPCGenSubtargetInfo(TT, CPU, TuneCPU, FS), TargetTriple(TT),
59 IsPPC64(TargetTriple.getArch() == Triple::ppc64 ||
60 TargetTriple.getArch() == Triple::ppc64le),
61 TM(TM), FrameLowering(initializeSubtargetDependencies(CPU, TuneCPU, FS)),
62 InstrInfo(*this), TLInfo(TM, *this) {
63 TSInfo = std::make_unique<PPCSelectionDAGInfo>();
64
65 CallLoweringInfo.reset(p: new PPCCallLowering(*getTargetLowering()));
66 Legalizer.reset(p: new PPCLegalizerInfo(*this));
67 auto *RBI = new PPCRegisterBankInfo(*getRegisterInfo());
68 RegBankInfo.reset(p: RBI);
69
70 InstSelector.reset(p: createPPCInstructionSelector(TM, *this, *RBI));
71}
72
73PPCSubtarget::~PPCSubtarget() = default;
74
75const SelectionDAGTargetInfo *PPCSubtarget::getSelectionDAGInfo() const {
76 return TSInfo.get();
77}
78
79void PPCSubtarget::initializeEnvironment() {
80 StackAlignment = Align(16);
81 CPUDirective = PPC::DIR_NONE;
82 HasPOPCNTD = POPCNTD_Unavailable;
83}
84
85void PPCSubtarget::initSubtargetFeatures(StringRef CPU, StringRef TuneCPU,
86 StringRef FS) {
87 // Determine default and user specified characteristics
88 std::string CPUName = std::string(CPU);
89 if (CPUName.empty() || CPU == "generic") {
90 if (TargetTriple.getSubArch() == Triple::PPCSubArch_spe)
91 CPUName = "e500";
92 else
93 CPUName = std::string(PPC::getNormalizedPPCTargetCPU(T: TargetTriple));
94 }
95
96 // Determine the CPU to schedule for.
97 if (TuneCPU.empty()) TuneCPU = CPUName;
98
99 // Initialize scheduling itinerary for the specified CPU.
100 InstrItins = getInstrItineraryForCPU(CPU: CPUName);
101
102 // Parse features string.
103 ParseSubtargetFeatures(CPU: CPUName, TuneCPU, FS);
104
105 // If the user requested use of 64-bit regs, but the cpu selected doesn't
106 // support it, ignore.
107 if (IsPPC64 && has64BitSupport())
108 Use64BitRegs = true;
109
110 if (TargetTriple.isPPC32SecurePlt())
111 IsSecurePlt = true;
112
113 if (HasSPE && IsPPC64)
114 report_fatal_error( reason: "SPE is only supported for 32-bit targets.\n", gen_crash_diag: false);
115 if (HasSPE && (HasAltivec || HasVSX || HasFPU))
116 report_fatal_error(
117 reason: "SPE and traditional floating point cannot both be enabled.\n", gen_crash_diag: false);
118
119 // If not SPE, set standard FPU
120 if (!HasSPE)
121 HasFPU = true;
122
123 StackAlignment = getPlatformStackAlignment();
124
125 // Determine endianness.
126 IsLittleEndian = TM.isLittleEndian();
127
128 if (HasAIXSmallLocalExecTLS || HasAIXSmallLocalDynamicTLS) {
129 if (!TargetTriple.isOSAIX() || !IsPPC64)
130 report_fatal_error(reason: "The aix-small-local-[exec|dynamic]-tls attribute is "
131 "only supported on AIX in "
132 "64-bit mode.\n",
133 gen_crash_diag: false);
134 // The aix-small-local-[exec|dynamic]-tls attribute should only be used with
135 // -data-sections, as having data sections turned off with this option
136 // is not ideal for performance. Moreover, the
137 // small-local-[exec|dynamic]-tls region is a limited resource, and should
138 // not be used for variables that may be replaced.
139 if (!TM.getDataSections())
140 report_fatal_error(reason: "The aix-small-local-[exec|dynamic]-tls attribute can "
141 "only be specified with "
142 "-data-sections.\n",
143 gen_crash_diag: false);
144 }
145
146 if (HasAIXShLibTLSModelOpt && (!TargetTriple.isOSAIX() || !IsPPC64))
147 report_fatal_error(reason: "The aix-shared-lib-tls-model-opt attribute "
148 "is only supported on AIX in 64-bit mode.\n",
149 gen_crash_diag: false);
150}
151
152bool PPCSubtarget::enableMachineScheduler() const { return true; }
153
154bool PPCSubtarget::enableMachinePipeliner() const {
155 return getSchedModel().hasInstrSchedModel() && EnableMachinePipeliner;
156}
157
158bool PPCSubtarget::useDFAforSMS() const { return false; }
159
160// This overrides the PostRAScheduler bit in the SchedModel for each CPU.
161bool PPCSubtarget::enablePostRAScheduler() const { return true; }
162
163PPCGenSubtargetInfo::AntiDepBreakMode PPCSubtarget::getAntiDepBreakMode() const {
164 return TargetSubtargetInfo::ANTIDEP_ALL;
165}
166
167void PPCSubtarget::getCriticalPathRCs(RegClassVector &CriticalPathRCs) const {
168 CriticalPathRCs.clear();
169 CriticalPathRCs.push_back(Elt: isPPC64() ?
170 &PPC::G8RCRegClass : &PPC::GPRCRegClass);
171}
172
173void PPCSubtarget::overrideSchedPolicy(MachineSchedPolicy &Policy,
174 unsigned NumRegionInstrs) const {
175 // The GenericScheduler that we use defaults to scheduling bottom up only.
176 // We want to schedule from both the top and the bottom and so we set
177 // OnlyBottomUp to false.
178 // We want to do bi-directional scheduling since it provides a more balanced
179 // schedule leading to better performance.
180 Policy.OnlyBottomUp = false;
181 // Spilling is generally expensive on all PPC cores, so always enable
182 // register-pressure tracking.
183 Policy.ShouldTrackPressure = true;
184}
185
186bool PPCSubtarget::useAA() const {
187 return true;
188}
189
190bool PPCSubtarget::enableSubRegLiveness() const { return true; }
191
192bool PPCSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const {
193 if (isAIXABI()) {
194 if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(Val: GV))
195 // On AIX the only symbols that aren't indirect are toc-data.
196 return !GVar->hasAttribute(Kind: "toc-data");
197
198 return true;
199 }
200
201 // Large code model always uses the TOC even for local symbols.
202 if (TM.getCodeModel() == CodeModel::Large)
203 return true;
204
205 if (TM.shouldAssumeDSOLocal(GV))
206 return false;
207 return true;
208}
209
210CodeModel::Model PPCSubtarget::getCodeModel(const TargetMachine &TM,
211 const GlobalValue *GV) const {
212 // If there isn't an attribute to override the module code model
213 // this will be the effective code model.
214 CodeModel::Model ModuleModel = TM.getCodeModel();
215
216 // Initially support per global code model for AIX only.
217 if (!isAIXABI())
218 return ModuleModel;
219
220 // Only GlobalVariables carry an attribute which can override the module code
221 // model.
222 assert(GV && "Unexpected NULL GlobalValue");
223 const GlobalVariable *GlobalVar =
224 [](const GlobalValue *GV) -> const GlobalVariable * {
225 const GlobalVariable *Var = dyn_cast<GlobalVariable>(Val: GV);
226 if (Var)
227 return Var;
228
229 const GlobalAlias *Alias = dyn_cast<GlobalAlias>(Val: GV);
230 if (Alias)
231 return dyn_cast<GlobalVariable>(Val: Alias->getAliaseeObject());
232
233 return nullptr;
234 }(GV);
235
236 if (!GlobalVar)
237 return ModuleModel;
238
239 std::optional<CodeModel::Model> MaybeCodeModel = GlobalVar->getCodeModel();
240 if (MaybeCodeModel) {
241 CodeModel::Model CM = *MaybeCodeModel;
242 assert((CM == CodeModel::Small || CM == CodeModel::Large) &&
243 "invalid code model for AIX");
244 return CM;
245 }
246
247 return ModuleModel;
248}
249
250bool PPCSubtarget::isELFv2ABI() const { return TM.isELFv2ABI(); }
251bool PPCSubtarget::isPPC64() const { return TM.isPPC64(); }
252
253bool PPCSubtarget::isUsingPCRelativeCalls() const {
254 return isPPC64() && hasPCRelativeMemops() && isELFv2ABI() &&
255 CodeModel::Medium == getTargetMachine().getCodeModel();
256}
257
258// GlobalISEL
259const CallLowering *PPCSubtarget::getCallLowering() const {
260 return CallLoweringInfo.get();
261}
262
263const RegisterBankInfo *PPCSubtarget::getRegBankInfo() const {
264 return RegBankInfo.get();
265}
266
267const LegalizerInfo *PPCSubtarget::getLegalizerInfo() const {
268 return Legalizer.get();
269}
270
271InstructionSelector *PPCSubtarget::getInstructionSelector() const {
272 return InstSelector.get();
273}
274