1//===-- MipsTargetMachine.cpp - Define TargetMachine for Mips -------------===//
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// Implements the info about Mips target spec.
10//
11//===----------------------------------------------------------------------===//
12
13#include "MipsTargetMachine.h"
14#include "MCTargetDesc/MipsABIInfo.h"
15#include "MCTargetDesc/MipsMCTargetDesc.h"
16#include "Mips.h"
17#include "Mips16ISelDAGToDAG.h"
18#include "MipsSEISelDAGToDAG.h"
19#include "MipsSubtarget.h"
20#include "MipsTargetObjectFile.h"
21#include "TargetInfo/MipsTargetInfo.h"
22#include "llvm/ADT/Optional.h"
23#include "llvm/ADT/STLExtras.h"
24#include "llvm/ADT/StringRef.h"
25#include "llvm/Analysis/TargetTransformInfo.h"
26#include "llvm/CodeGen/BasicTTIImpl.h"
27#include "llvm/CodeGen/GlobalISel/IRTranslator.h"
28#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
29#include "llvm/CodeGen/GlobalISel/Legalizer.h"
30#include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
31#include "llvm/CodeGen/MachineFunction.h"
32#include "llvm/CodeGen/Passes.h"
33#include "llvm/CodeGen/TargetPassConfig.h"
34#include "llvm/IR/Attributes.h"
35#include "llvm/IR/Function.h"
36#include "llvm/InitializePasses.h"
37#include "llvm/Support/CodeGen.h"
38#include "llvm/Support/Debug.h"
39#include "llvm/Support/TargetRegistry.h"
40#include "llvm/Support/raw_ostream.h"
41#include "llvm/Target/TargetOptions.h"
42#include <string>
43
44using namespace llvm;
45
46#define DEBUG_TYPE "mips"
47
48extern "C" LLVM_EXTERNAL_VISIBILITY void LLVMInitializeMipsTarget() {
49  // Register the target.
50  RegisterTargetMachine<MipsebTargetMachine> X(getTheMipsTarget());
51  RegisterTargetMachine<MipselTargetMachine> Y(getTheMipselTarget());
52  RegisterTargetMachine<MipsebTargetMachine> A(getTheMips64Target());
53  RegisterTargetMachine<MipselTargetMachine> B(getTheMips64elTarget());
54
55  PassRegistry *PR = PassRegistry::getPassRegistry();
56  initializeGlobalISel(*PR);
57  initializeMipsDelaySlotFillerPass(*PR);
58  initializeMipsBranchExpansionPass(*PR);
59  initializeMicroMipsSizeReducePass(*PR);
60  initializeMipsPreLegalizerCombinerPass(*PR);
61}
62
63static std::string computeDataLayout(const Triple &TT, StringRef CPU,
64                                     const TargetOptions &Options,
65                                     bool isLittle) {
66  std::string Ret;
67  MipsABIInfo ABI = MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions);
68
69  // There are both little and big endian mips.
70  if (isLittle)
71    Ret += "e";
72  else
73    Ret += "E";
74
75  if (ABI.IsO32())
76    Ret += "-m:m";
77  else
78    Ret += "-m:e";
79
80  // Pointers are 32 bit on some ABIs.
81  if (!ABI.IsN64())
82    Ret += "-p:32:32";
83
84  // 8 and 16 bit integers only need to have natural alignment, but try to
85  // align them to 32 bits. 64 bit integers have natural alignment.
86  Ret += "-i8:8:32-i16:16:32-i64:64";
87
88  // 32 bit registers are always available and the stack is at least 64 bit
89  // aligned. On N64 64 bit registers are also available and the stack is
90  // 128 bit aligned.
91  if (ABI.IsN64() || ABI.IsN32())
92    Ret += "-n32:64-S128";
93  else
94    Ret += "-n32-S64";
95
96  return Ret;
97}
98
99static Reloc::Model getEffectiveRelocModel(bool JIT,
100                                           Optional<Reloc::Model> RM) {
101  if (!RM.hasValue() || JIT)
102    return Reloc::Static;
103  return *RM;
104}
105
106// On function prologue, the stack is created by decrementing
107// its pointer. Once decremented, all references are done with positive
108// offset from the stack/frame pointer, using StackGrowsUp enables
109// an easier handling.
110// Using CodeModel::Large enables different CALL behavior.
111MipsTargetMachine::MipsTargetMachine(const Target &T, const Triple &TT,
112                                     StringRef CPU, StringRef FS,
113                                     const TargetOptions &Options,
114                                     Optional<Reloc::Model> RM,
115                                     Optional<CodeModel::Model> CM,
116                                     CodeGenOpt::Level OL, bool JIT,
117                                     bool isLittle)
118    : LLVMTargetMachine(T, computeDataLayout(TT, CPU, Options, isLittle), TT,
119                        CPU, FS, Options, getEffectiveRelocModel(JIT, RM),
120                        getEffectiveCodeModel(CM, CodeModel::Small), OL),
121      isLittle(isLittle), TLOF(std::make_unique<MipsTargetObjectFile>()),
122      ABI(MipsABIInfo::computeTargetABI(TT, CPU, Options.MCOptions)),
123      Subtarget(nullptr),
124      DefaultSubtarget(TT, CPU, FS, isLittle, *this,
125                       MaybeAlign(Options.StackAlignmentOverride)),
126      NoMips16Subtarget(TT, CPU, FS.empty() ? "-mips16" : FS.str() + ",-mips16",
127                        isLittle, *this,
128                        MaybeAlign(Options.StackAlignmentOverride)),
129      Mips16Subtarget(TT, CPU, FS.empty() ? "+mips16" : FS.str() + ",+mips16",
130                      isLittle, *this,
131                      MaybeAlign(Options.StackAlignmentOverride)) {
132  Subtarget = &DefaultSubtarget;
133  initAsmInfo();
134
135  // Mips supports the debug entry values.
136  setSupportsDebugEntryValues(true);
137}
138
139MipsTargetMachine::~MipsTargetMachine() = default;
140
141void MipsebTargetMachine::anchor() {}
142
143MipsebTargetMachine::MipsebTargetMachine(const Target &T, const Triple &TT,
144                                         StringRef CPU, StringRef FS,
145                                         const TargetOptions &Options,
146                                         Optional<Reloc::Model> RM,
147                                         Optional<CodeModel::Model> CM,
148                                         CodeGenOpt::Level OL, bool JIT)
149    : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, false) {}
150
151void MipselTargetMachine::anchor() {}
152
153MipselTargetMachine::MipselTargetMachine(const Target &T, const Triple &TT,
154                                         StringRef CPU, StringRef FS,
155                                         const TargetOptions &Options,
156                                         Optional<Reloc::Model> RM,
157                                         Optional<CodeModel::Model> CM,
158                                         CodeGenOpt::Level OL, bool JIT)
159    : MipsTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, JIT, true) {}
160
161const MipsSubtarget *
162MipsTargetMachine::getSubtargetImpl(const Function &F) const {
163  Attribute CPUAttr = F.getFnAttribute("target-cpu");
164  Attribute FSAttr = F.getFnAttribute("target-features");
165
166  std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
167                        ? CPUAttr.getValueAsString().str()
168                        : TargetCPU;
169  std::string FS = !FSAttr.hasAttribute(Attribute::None)
170                       ? FSAttr.getValueAsString().str()
171                       : TargetFS;
172  bool hasMips16Attr =
173      !F.getFnAttribute("mips16").hasAttribute(Attribute::None);
174  bool hasNoMips16Attr =
175      !F.getFnAttribute("nomips16").hasAttribute(Attribute::None);
176
177  bool HasMicroMipsAttr =
178      !F.getFnAttribute("micromips").hasAttribute(Attribute::None);
179  bool HasNoMicroMipsAttr =
180      !F.getFnAttribute("nomicromips").hasAttribute(Attribute::None);
181
182  // FIXME: This is related to the code below to reset the target options,
183  // we need to know whether or not the soft float flag is set on the
184  // function, so we can enable it as a subtarget feature.
185  bool softFloat =
186      F.hasFnAttribute("use-soft-float") &&
187      F.getFnAttribute("use-soft-float").getValueAsString() == "true";
188
189  if (hasMips16Attr)
190    FS += FS.empty() ? "+mips16" : ",+mips16";
191  else if (hasNoMips16Attr)
192    FS += FS.empty() ? "-mips16" : ",-mips16";
193  if (HasMicroMipsAttr)
194    FS += FS.empty() ? "+micromips" : ",+micromips";
195  else if (HasNoMicroMipsAttr)
196    FS += FS.empty() ? "-micromips" : ",-micromips";
197  if (softFloat)
198    FS += FS.empty() ? "+soft-float" : ",+soft-float";
199
200  auto &I = SubtargetMap[CPU + FS];
201  if (!I) {
202    // This needs to be done before we create a new subtarget since any
203    // creation will depend on the TM and the code generation flags on the
204    // function that reside in TargetOptions.
205    resetTargetOptions(F);
206    I = std::make_unique<MipsSubtarget>(
207        TargetTriple, CPU, FS, isLittle, *this,
208        MaybeAlign(Options.StackAlignmentOverride));
209  }
210  return I.get();
211}
212
213void MipsTargetMachine::resetSubtarget(MachineFunction *MF) {
214  LLVM_DEBUG(dbgs() << "resetSubtarget\n");
215
216  Subtarget = &MF->getSubtarget<MipsSubtarget>();
217}
218
219namespace {
220
221/// Mips Code Generator Pass Configuration Options.
222class MipsPassConfig : public TargetPassConfig {
223public:
224  MipsPassConfig(MipsTargetMachine &TM, PassManagerBase &PM)
225      : TargetPassConfig(TM, PM) {
226    // The current implementation of long branch pass requires a scratch
227    // register ($at) to be available before branch instructions. Tail merging
228    // can break this requirement, so disable it when long branch pass is
229    // enabled.
230    EnableTailMerge = !getMipsSubtarget().enableLongBranchPass();
231  }
232
233  MipsTargetMachine &getMipsTargetMachine() const {
234    return getTM<MipsTargetMachine>();
235  }
236
237  const MipsSubtarget &getMipsSubtarget() const {
238    return *getMipsTargetMachine().getSubtargetImpl();
239  }
240
241  void addIRPasses() override;
242  bool addInstSelector() override;
243  void addPreEmitPass() override;
244  void addPreRegAlloc() override;
245  bool addIRTranslator() override;
246  void addPreLegalizeMachineIR() override;
247  bool addLegalizeMachineIR() override;
248  bool addRegBankSelect() override;
249  bool addGlobalInstructionSelect() override;
250
251  std::unique_ptr<CSEConfigBase> getCSEConfig() const override;
252};
253
254} // end anonymous namespace
255
256TargetPassConfig *MipsTargetMachine::createPassConfig(PassManagerBase &PM) {
257  return new MipsPassConfig(*this, PM);
258}
259
260std::unique_ptr<CSEConfigBase> MipsPassConfig::getCSEConfig() const {
261  return getStandardCSEConfigForOpt(TM->getOptLevel());
262}
263
264void MipsPassConfig::addIRPasses() {
265  TargetPassConfig::addIRPasses();
266  addPass(createAtomicExpandPass());
267  if (getMipsSubtarget().os16())
268    addPass(createMipsOs16Pass());
269  if (getMipsSubtarget().inMips16HardFloat())
270    addPass(createMips16HardFloatPass());
271}
272// Install an instruction selector pass using
273// the ISelDag to gen Mips code.
274bool MipsPassConfig::addInstSelector() {
275  addPass(createMipsModuleISelDagPass());
276  addPass(createMips16ISelDag(getMipsTargetMachine(), getOptLevel()));
277  addPass(createMipsSEISelDag(getMipsTargetMachine(), getOptLevel()));
278  return false;
279}
280
281void MipsPassConfig::addPreRegAlloc() {
282  addPass(createMipsOptimizePICCallPass());
283}
284
285TargetTransformInfo
286MipsTargetMachine::getTargetTransformInfo(const Function &F) {
287  if (Subtarget->allowMixed16_32()) {
288    LLVM_DEBUG(errs() << "No Target Transform Info Pass Added\n");
289    // FIXME: This is no longer necessary as the TTI returned is per-function.
290    return TargetTransformInfo(F.getParent()->getDataLayout());
291  }
292
293  LLVM_DEBUG(errs() << "Target Transform Info Pass Added\n");
294  return TargetTransformInfo(BasicTTIImpl(this, F));
295}
296
297// Implemented by targets that want to run passes immediately before
298// machine code is emitted. return true if -print-machineinstrs should
299// print out the code after the passes.
300void MipsPassConfig::addPreEmitPass() {
301  // Expand pseudo instructions that are sensitive to register allocation.
302  addPass(createMipsExpandPseudoPass());
303
304  // The microMIPS size reduction pass performs instruction reselection for
305  // instructions which can be remapped to a 16 bit instruction.
306  addPass(createMicroMipsSizeReducePass());
307
308  // The delay slot filler pass can potientially create forbidden slot hazards
309  // for MIPSR6 and therefore it should go before MipsBranchExpansion pass.
310  addPass(createMipsDelaySlotFillerPass());
311
312  // This pass expands branches and takes care about the forbidden slot hazards.
313  // Expanding branches may potentially create forbidden slot hazards for
314  // MIPSR6, and fixing such hazard may potentially break a branch by extending
315  // its offset out of range. That's why this pass combine these two tasks, and
316  // runs them alternately until one of them finishes without any changes. Only
317  // then we can be sure that all branches are expanded properly and no hazards
318  // exists.
319  // Any new pass should go before this pass.
320  addPass(createMipsBranchExpansion());
321
322  addPass(createMipsConstantIslandPass());
323}
324
325bool MipsPassConfig::addIRTranslator() {
326  addPass(new IRTranslator());
327  return false;
328}
329
330void MipsPassConfig::addPreLegalizeMachineIR() {
331  addPass(createMipsPreLegalizeCombiner());
332}
333
334bool MipsPassConfig::addLegalizeMachineIR() {
335  addPass(new Legalizer());
336  return false;
337}
338
339bool MipsPassConfig::addRegBankSelect() {
340  addPass(new RegBankSelect());
341  return false;
342}
343
344bool MipsPassConfig::addGlobalInstructionSelect() {
345  addPass(new InstructionSelect());
346  return false;
347}
348