1 //===-- X86TargetMachine.cpp - Define TargetMachine for the X86 -----------===//
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 // This file defines the X86 specific subclass of TargetMachine.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "X86TargetMachine.h"
15 #include "X86.h"
16 #include "X86TargetObjectFile.h"
17 #include "X86TargetTransformInfo.h"
18 #include "llvm/CodeGen/Passes.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/IR/LegacyPassManager.h"
21 #include "llvm/Support/CommandLine.h"
22 #include "llvm/Support/FormattedStream.h"
23 #include "llvm/Support/TargetRegistry.h"
24 #include "llvm/Target/TargetOptions.h"
25 using namespace llvm;
26
27 static cl::opt<bool> EnableMachineCombinerPass("x86-machine-combiner",
28 cl::desc("Enable the machine combiner pass"),
29 cl::init(true), cl::Hidden);
30
31 namespace llvm {
32 void initializeWinEHStatePassPass(PassRegistry &);
33 }
34
LLVMInitializeX86Target()35 extern "C" void LLVMInitializeX86Target() {
36 // Register the target.
37 RegisterTargetMachine<X86TargetMachine> X(TheX86_32Target);
38 RegisterTargetMachine<X86TargetMachine> Y(TheX86_64Target);
39
40 PassRegistry &PR = *PassRegistry::getPassRegistry();
41 initializeWinEHStatePassPass(PR);
42 }
43
createTLOF(const Triple & TT)44 static std::unique_ptr<TargetLoweringObjectFile> createTLOF(const Triple &TT) {
45 if (TT.isOSBinFormatMachO()) {
46 if (TT.getArch() == Triple::x86_64)
47 return make_unique<X86_64MachoTargetObjectFile>();
48 return make_unique<TargetLoweringObjectFileMachO>();
49 }
50
51 if (TT.isOSLinux() || TT.isOSNaCl())
52 return make_unique<X86LinuxNaClTargetObjectFile>();
53 if (TT.isOSBinFormatELF())
54 return make_unique<X86ELFTargetObjectFile>();
55 if (TT.isKnownWindowsMSVCEnvironment() || TT.isWindowsCoreCLREnvironment())
56 return make_unique<X86WindowsTargetObjectFile>();
57 if (TT.isOSBinFormatCOFF())
58 return make_unique<TargetLoweringObjectFileCOFF>();
59 llvm_unreachable("unknown subtarget type");
60 }
61
computeDataLayout(const Triple & TT)62 static std::string computeDataLayout(const Triple &TT) {
63 // X86 is little endian
64 std::string Ret = "e";
65
66 Ret += DataLayout::getManglingComponent(TT);
67 // X86 and x32 have 32 bit pointers.
68 if ((TT.isArch64Bit() &&
69 (TT.getEnvironment() == Triple::GNUX32 || TT.isOSNaCl())) ||
70 !TT.isArch64Bit())
71 Ret += "-p:32:32";
72
73 // Some ABIs align 64 bit integers and doubles to 64 bits, others to 32.
74 if (TT.isArch64Bit() || TT.isOSWindows() || TT.isOSNaCl())
75 Ret += "-i64:64";
76 else
77 Ret += "-f64:32:64";
78
79 // Some ABIs align long double to 128 bits, others to 32.
80 if (TT.isOSNaCl())
81 ; // No f80
82 else if (TT.isArch64Bit() || TT.isOSDarwin())
83 Ret += "-f80:128";
84 else
85 Ret += "-f80:32";
86
87 // The registers can hold 8, 16, 32 or, in x86-64, 64 bits.
88 if (TT.isArch64Bit())
89 Ret += "-n8:16:32:64";
90 else
91 Ret += "-n8:16:32";
92
93 // The stack is aligned to 32 bits on some ABIs and 128 bits on others.
94 if (!TT.isArch64Bit() && TT.isOSWindows())
95 Ret += "-a:0:32-S32";
96 else
97 Ret += "-S128";
98
99 return Ret;
100 }
101
102 /// X86TargetMachine ctor - Create an X86 target.
103 ///
X86TargetMachine(const Target & T,const Triple & TT,StringRef CPU,StringRef FS,const TargetOptions & Options,Reloc::Model RM,CodeModel::Model CM,CodeGenOpt::Level OL)104 X86TargetMachine::X86TargetMachine(const Target &T, const Triple &TT,
105 StringRef CPU, StringRef FS,
106 const TargetOptions &Options,
107 Reloc::Model RM, CodeModel::Model CM,
108 CodeGenOpt::Level OL)
109 : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options, RM, CM,
110 OL),
111 TLOF(createTLOF(getTargetTriple())),
112 Subtarget(TT, CPU, FS, *this, Options.StackAlignmentOverride) {
113 // Windows stack unwinder gets confused when execution flow "falls through"
114 // after a call to 'noreturn' function.
115 // To prevent that, we emit a trap for 'unreachable' IR instructions.
116 // (which on X86, happens to be the 'ud2' instruction)
117 if (Subtarget.isTargetWin64())
118 this->Options.TrapUnreachable = true;
119
120 // By default (and when -ffast-math is on), enable estimate codegen for
121 // everything except scalar division. By default, use 1 refinement step for
122 // all operations. Defaults may be overridden by using command-line options.
123 // Scalar division estimates are disabled because they break too much
124 // real-world code. These defaults match GCC behavior.
125 this->Options.Reciprocals.setDefaults("sqrtf", true, 1);
126 this->Options.Reciprocals.setDefaults("divf", false, 1);
127 this->Options.Reciprocals.setDefaults("vec-sqrtf", true, 1);
128 this->Options.Reciprocals.setDefaults("vec-divf", true, 1);
129
130 initAsmInfo();
131 }
132
~X86TargetMachine()133 X86TargetMachine::~X86TargetMachine() {}
134
135 const X86Subtarget *
getSubtargetImpl(const Function & F) const136 X86TargetMachine::getSubtargetImpl(const Function &F) const {
137 Attribute CPUAttr = F.getFnAttribute("target-cpu");
138 Attribute FSAttr = F.getFnAttribute("target-features");
139
140 std::string CPU = !CPUAttr.hasAttribute(Attribute::None)
141 ? CPUAttr.getValueAsString().str()
142 : TargetCPU;
143 std::string FS = !FSAttr.hasAttribute(Attribute::None)
144 ? FSAttr.getValueAsString().str()
145 : TargetFS;
146
147 // FIXME: This is related to the code below to reset the target options,
148 // we need to know whether or not the soft float flag is set on the
149 // function before we can generate a subtarget. We also need to use
150 // it as a key for the subtarget since that can be the only difference
151 // between two functions.
152 bool SoftFloat =
153 F.hasFnAttribute("use-soft-float") &&
154 F.getFnAttribute("use-soft-float").getValueAsString() == "true";
155 // If the soft float attribute is set on the function turn on the soft float
156 // subtarget feature.
157 if (SoftFloat)
158 FS += FS.empty() ? "+soft-float" : ",+soft-float";
159
160 auto &I = SubtargetMap[CPU + FS];
161 if (!I) {
162 // This needs to be done before we create a new subtarget since any
163 // creation will depend on the TM and the code generation flags on the
164 // function that reside in TargetOptions.
165 resetTargetOptions(F);
166 I = llvm::make_unique<X86Subtarget>(TargetTriple, CPU, FS, *this,
167 Options.StackAlignmentOverride);
168 }
169 return I.get();
170 }
171
172 //===----------------------------------------------------------------------===//
173 // Command line options for x86
174 //===----------------------------------------------------------------------===//
175 static cl::opt<bool>
176 UseVZeroUpper("x86-use-vzeroupper", cl::Hidden,
177 cl::desc("Minimize AVX to SSE transition penalty"),
178 cl::init(true));
179
180 //===----------------------------------------------------------------------===//
181 // X86 TTI query.
182 //===----------------------------------------------------------------------===//
183
getTargetIRAnalysis()184 TargetIRAnalysis X86TargetMachine::getTargetIRAnalysis() {
185 return TargetIRAnalysis([this](const Function &F) {
186 return TargetTransformInfo(X86TTIImpl(this, F));
187 });
188 }
189
190
191 //===----------------------------------------------------------------------===//
192 // Pass Pipeline Configuration
193 //===----------------------------------------------------------------------===//
194
195 namespace {
196 /// X86 Code Generator Pass Configuration Options.
197 class X86PassConfig : public TargetPassConfig {
198 public:
X86PassConfig(X86TargetMachine * TM,PassManagerBase & PM)199 X86PassConfig(X86TargetMachine *TM, PassManagerBase &PM)
200 : TargetPassConfig(TM, PM) {}
201
getX86TargetMachine() const202 X86TargetMachine &getX86TargetMachine() const {
203 return getTM<X86TargetMachine>();
204 }
205
206 void addIRPasses() override;
207 bool addInstSelector() override;
208 bool addILPOpts() override;
209 bool addPreISel() override;
210 void addPreRegAlloc() override;
211 void addPostRegAlloc() override;
212 void addPreEmitPass() override;
213 void addPreSched2() override;
214 };
215 } // namespace
216
createPassConfig(PassManagerBase & PM)217 TargetPassConfig *X86TargetMachine::createPassConfig(PassManagerBase &PM) {
218 return new X86PassConfig(this, PM);
219 }
220
addIRPasses()221 void X86PassConfig::addIRPasses() {
222 addPass(createAtomicExpandPass(&getX86TargetMachine()));
223
224 TargetPassConfig::addIRPasses();
225 }
226
addInstSelector()227 bool X86PassConfig::addInstSelector() {
228 // Install an instruction selector.
229 addPass(createX86ISelDag(getX86TargetMachine(), getOptLevel()));
230
231 // For ELF, cleanup any local-dynamic TLS accesses.
232 if (TM->getTargetTriple().isOSBinFormatELF() &&
233 getOptLevel() != CodeGenOpt::None)
234 addPass(createCleanupLocalDynamicTLSPass());
235
236 addPass(createX86GlobalBaseRegPass());
237
238 return false;
239 }
240
addILPOpts()241 bool X86PassConfig::addILPOpts() {
242 addPass(&EarlyIfConverterID);
243 if (EnableMachineCombinerPass)
244 addPass(&MachineCombinerID);
245 return true;
246 }
247
addPreISel()248 bool X86PassConfig::addPreISel() {
249 // Only add this pass for 32-bit x86 Windows.
250 const Triple &TT = TM->getTargetTriple();
251 if (TT.isOSWindows() && TT.getArch() == Triple::x86)
252 addPass(createX86WinEHStatePass());
253 return true;
254 }
255
addPreRegAlloc()256 void X86PassConfig::addPreRegAlloc() {
257 if (getOptLevel() != CodeGenOpt::None)
258 addPass(createX86OptimizeLEAs());
259
260 addPass(createX86CallFrameOptimization());
261 }
262
addPostRegAlloc()263 void X86PassConfig::addPostRegAlloc() {
264 addPass(createX86FloatingPointStackifierPass());
265 }
266
addPreSched2()267 void X86PassConfig::addPreSched2() { addPass(createX86ExpandPseudoPass()); }
268
addPreEmitPass()269 void X86PassConfig::addPreEmitPass() {
270 if (getOptLevel() != CodeGenOpt::None)
271 addPass(createExecutionDependencyFixPass(&X86::VR128RegClass));
272
273 if (UseVZeroUpper)
274 addPass(createX86IssueVZeroUpperPass());
275
276 if (getOptLevel() != CodeGenOpt::None) {
277 addPass(createX86PadShortFunctions());
278 addPass(createX86FixupLEAs());
279 }
280 }
281