1 //===-- ARMTargetMachine.cpp - Define TargetMachine for ARM ---------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "ARM.h"
14 #include "ARMTargetMachine.h"
15 #include "ARMFrameLowering.h"
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/MC/MCAsmInfo.h"
18 #include "llvm/PassManager.h"
19 #include "llvm/Support/CommandLine.h"
20 #include "llvm/Support/FormattedStream.h"
21 #include "llvm/Support/TargetRegistry.h"
22 #include "llvm/Target/TargetOptions.h"
23 #include "llvm/Transforms/Scalar.h"
24 using namespace llvm;
25 
26 static cl::opt<bool>
27 DisableA15SDOptimization("disable-a15-sd-optimization", cl::Hidden,
28                    cl::desc("Inhibit optimization of S->D register accesses on A15"),
29                    cl::init(false));
30 
31 static cl::opt<bool>
32 EnableAtomicTidy("arm-atomic-cfg-tidy", cl::Hidden,
33                  cl::desc("Run SimplifyCFG after expanding atomic operations"
34                           " to make use of cmpxchg flow-based information"),
35                  cl::init(true));
36 
37 extern "C" void LLVMInitializeARMTarget() {
38   // Register the target.
39   RegisterTargetMachine<ARMLETargetMachine> X(TheARMLETarget);
40   RegisterTargetMachine<ARMBETargetMachine> Y(TheARMBETarget);
41   RegisterTargetMachine<ThumbLETargetMachine> A(TheThumbLETarget);
42   RegisterTargetMachine<ThumbBETargetMachine> B(TheThumbBETarget);
43 }
44 
45 
46 /// TargetMachine ctor - Create an ARM architecture model.
47 ///
48 ARMBaseTargetMachine::ARMBaseTargetMachine(const Target &T, StringRef TT,
49                                            StringRef CPU, StringRef FS,
50                                            const TargetOptions &Options,
51                                            Reloc::Model RM, CodeModel::Model CM,
52                                            CodeGenOpt::Level OL, bool isLittle)
53     : LLVMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL),
54       Subtarget(TT, CPU, FS, *this, isLittle, Options) {
55 
56   // Default to triple-appropriate float ABI
57   if (Options.FloatABIType == FloatABI::Default)
58     this->Options.FloatABIType =
59         Subtarget.isTargetHardFloat() ? FloatABI::Hard : FloatABI::Soft;
60 }
61 
62 void ARMBaseTargetMachine::addAnalysisPasses(PassManagerBase &PM) {
63   // Add first the target-independent BasicTTI pass, then our ARM pass. This
64   // allows the ARM pass to delegate to the target independent layer when
65   // appropriate.
66   PM.add(createBasicTargetTransformInfoPass(this));
67   PM.add(createARMTargetTransformInfoPass(this));
68 }
69 
70 
71 void ARMTargetMachine::anchor() { }
72 
73 ARMTargetMachine::ARMTargetMachine(const Target &T, StringRef TT, StringRef CPU,
74                                    StringRef FS, const TargetOptions &Options,
75                                    Reloc::Model RM, CodeModel::Model CM,
76                                    CodeGenOpt::Level OL, bool isLittle)
77     : ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, isLittle) {
78   initAsmInfo();
79   if (!Subtarget.hasARMOps())
80     report_fatal_error("CPU: '" + Subtarget.getCPUString() + "' does not "
81                        "support ARM mode execution!");
82 }
83 
84 void ARMLETargetMachine::anchor() { }
85 
86 ARMLETargetMachine::ARMLETargetMachine(const Target &T, StringRef TT,
87                                        StringRef CPU, StringRef FS,
88                                        const TargetOptions &Options,
89                                        Reloc::Model RM, CodeModel::Model CM,
90                                        CodeGenOpt::Level OL)
91     : ARMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}
92 
93 void ARMBETargetMachine::anchor() { }
94 
95 ARMBETargetMachine::ARMBETargetMachine(const Target &T, StringRef TT,
96                                        StringRef CPU, StringRef FS,
97                                        const TargetOptions &Options,
98                                        Reloc::Model RM, CodeModel::Model CM,
99                                        CodeGenOpt::Level OL)
100     : ARMTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, false) {}
101 
102 void ThumbTargetMachine::anchor() { }
103 
104 ThumbTargetMachine::ThumbTargetMachine(const Target &T, StringRef TT,
105                                        StringRef CPU, StringRef FS,
106                                        const TargetOptions &Options,
107                                        Reloc::Model RM, CodeModel::Model CM,
108                                        CodeGenOpt::Level OL, bool isLittle)
109     : ARMBaseTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL,
110                            isLittle) {
111   initAsmInfo();
112 }
113 
114 void ThumbLETargetMachine::anchor() { }
115 
116 ThumbLETargetMachine::ThumbLETargetMachine(const Target &T, StringRef TT,
117                                            StringRef CPU, StringRef FS,
118                                            const TargetOptions &Options,
119                                            Reloc::Model RM, CodeModel::Model CM,
120                                            CodeGenOpt::Level OL)
121     : ThumbTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, true) {}
122 
123 void ThumbBETargetMachine::anchor() { }
124 
125 ThumbBETargetMachine::ThumbBETargetMachine(const Target &T, StringRef TT,
126                                            StringRef CPU, StringRef FS,
127                                            const TargetOptions &Options,
128                                            Reloc::Model RM, CodeModel::Model CM,
129                                            CodeGenOpt::Level OL)
130     : ThumbTargetMachine(T, TT, CPU, FS, Options, RM, CM, OL, false) {}
131 
132 namespace {
133 /// ARM Code Generator Pass Configuration Options.
134 class ARMPassConfig : public TargetPassConfig {
135 public:
136   ARMPassConfig(ARMBaseTargetMachine *TM, PassManagerBase &PM)
137     : TargetPassConfig(TM, PM) {}
138 
139   ARMBaseTargetMachine &getARMTargetMachine() const {
140     return getTM<ARMBaseTargetMachine>();
141   }
142 
143   const ARMSubtarget &getARMSubtarget() const {
144     return *getARMTargetMachine().getSubtargetImpl();
145   }
146 
147   void addIRPasses() override;
148   bool addPreISel() override;
149   bool addInstSelector() override;
150   bool addPreRegAlloc() override;
151   bool addPreSched2() override;
152   bool addPreEmitPass() override;
153 };
154 } // namespace
155 
156 TargetPassConfig *ARMBaseTargetMachine::createPassConfig(PassManagerBase &PM) {
157   return new ARMPassConfig(this, PM);
158 }
159 
160 void ARMPassConfig::addIRPasses() {
161   addPass(createAtomicExpandLoadLinkedPass(TM));
162 
163   // Cmpxchg instructions are often used with a subsequent comparison to
164   // determine whether it succeeded. We can exploit existing control-flow in
165   // ldrex/strex loops to simplify this, but it needs tidying up.
166   const ARMSubtarget *Subtarget = &getARMSubtarget();
167   if (Subtarget->hasAnyDataBarrier() && !Subtarget->isThumb1Only())
168     if (TM->getOptLevel() != CodeGenOpt::None && EnableAtomicTidy)
169       addPass(createCFGSimplificationPass());
170 
171   TargetPassConfig::addIRPasses();
172 }
173 
174 bool ARMPassConfig::addPreISel() {
175   if (TM->getOptLevel() != CodeGenOpt::None)
176     addPass(createGlobalMergePass(TM));
177 
178   return false;
179 }
180 
181 bool ARMPassConfig::addInstSelector() {
182   addPass(createARMISelDag(getARMTargetMachine(), getOptLevel()));
183 
184   const ARMSubtarget *Subtarget = &getARMSubtarget();
185   if (Subtarget->isTargetELF() && !Subtarget->isThumb1Only() &&
186       TM->Options.EnableFastISel)
187     addPass(createARMGlobalBaseRegPass());
188   return false;
189 }
190 
191 bool ARMPassConfig::addPreRegAlloc() {
192   if (getOptLevel() != CodeGenOpt::None)
193     addPass(createARMLoadStoreOptimizationPass(true));
194   if (getOptLevel() != CodeGenOpt::None && getARMSubtarget().isCortexA9())
195     addPass(createMLxExpansionPass());
196   // Since the A15SDOptimizer pass can insert VDUP instructions, it can only be
197   // enabled when NEON is available.
198   if (getOptLevel() != CodeGenOpt::None && getARMSubtarget().isCortexA15() &&
199     getARMSubtarget().hasNEON() && !DisableA15SDOptimization) {
200     addPass(createA15SDOptimizerPass());
201   }
202   return true;
203 }
204 
205 bool ARMPassConfig::addPreSched2() {
206   if (getOptLevel() != CodeGenOpt::None) {
207     addPass(createARMLoadStoreOptimizationPass());
208     printAndVerify("After ARM load / store optimizer");
209 
210     if (getARMSubtarget().hasNEON())
211       addPass(createExecutionDependencyFixPass(&ARM::DPRRegClass));
212   }
213 
214   // Expand some pseudo instructions into multiple instructions to allow
215   // proper scheduling.
216   addPass(createARMExpandPseudoPass());
217 
218   if (getOptLevel() != CodeGenOpt::None) {
219     if (!getARMSubtarget().isThumb1Only()) {
220       // in v8, IfConversion depends on Thumb instruction widths
221       if (getARMSubtarget().restrictIT() &&
222           !getARMSubtarget().prefers32BitThumb())
223         addPass(createThumb2SizeReductionPass());
224       addPass(&IfConverterID);
225     }
226   }
227   if (getARMSubtarget().isThumb2())
228     addPass(createThumb2ITBlockPass());
229 
230   return true;
231 }
232 
233 bool ARMPassConfig::addPreEmitPass() {
234   if (getARMSubtarget().isThumb2()) {
235     if (!getARMSubtarget().prefers32BitThumb())
236       addPass(createThumb2SizeReductionPass());
237 
238     // Constant island pass work on unbundled instructions.
239     addPass(&UnpackMachineBundlesID);
240   }
241 
242   addPass(createARMOptimizeBarriersPass());
243   addPass(createARMConstantIslandPass());
244 
245   return true;
246 }
247 
248 bool ARMBaseTargetMachine::addCodeEmitter(PassManagerBase &PM,
249                                           JITCodeEmitter &JCE) {
250   // Machine code emitter pass for ARM.
251   PM.add(createARMJITCodeEmitterPass(*this, JCE));
252   return false;
253 }
254