X86TargetMachine.cpp revision 202878 
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 "X86MCAsmInfo.h"
15#include "X86TargetMachine.h"
16#include "X86.h"
17#include "llvm/PassManager.h"
18#include "llvm/CodeGen/MachineFunction.h"
19#include "llvm/CodeGen/Passes.h"
20#include "llvm/Support/FormattedStream.h"
21#include "llvm/Target/TargetOptions.h"
22#include "llvm/Target/TargetRegistry.h"
23using namespace llvm;
24
25static const MCAsmInfo *createMCAsmInfo(const Target &T, StringRef TT) {
26  Triple TheTriple(TT);
27  switch (TheTriple.getOS()) {
28  case Triple::Darwin:
29    return new X86MCAsmInfoDarwin(TheTriple);
30  case Triple::MinGW32:
31  case Triple::MinGW64:
32  case Triple::Cygwin:
33    return new X86MCAsmInfoCOFF(TheTriple);
34  case Triple::Win32:
35    return new X86WinMCAsmInfo(TheTriple);
36  default:
37    return new X86ELFMCAsmInfo(TheTriple);
38  }
39}
40
41extern "C" void LLVMInitializeX86Target() {
42  // Register the target.
43  RegisterTargetMachine<X86_32TargetMachine> X(TheX86_32Target);
44  RegisterTargetMachine<X86_64TargetMachine> Y(TheX86_64Target);
45
46  // Register the target asm info.
47  RegisterAsmInfoFn A(TheX86_32Target, createMCAsmInfo);
48  RegisterAsmInfoFn B(TheX86_64Target, createMCAsmInfo);
49
50  // Register the code emitter.
51  TargetRegistry::RegisterCodeEmitter(TheX86_32Target, createX86MCCodeEmitter);
52  TargetRegistry::RegisterCodeEmitter(TheX86_64Target, createX86MCCodeEmitter);
53}
54
55
56X86_32TargetMachine::X86_32TargetMachine(const Target &T, const std::string &TT,
57                                         const std::string &FS)
58  : X86TargetMachine(T, TT, FS, false) {
59}
60
61
62X86_64TargetMachine::X86_64TargetMachine(const Target &T, const std::string &TT,
63                                         const std::string &FS)
64  : X86TargetMachine(T, TT, FS, true) {
65}
66
67/// X86TargetMachine ctor - Create an X86 target.
68///
69X86TargetMachine::X86TargetMachine(const Target &T, const std::string &TT,
70                                   const std::string &FS, bool is64Bit)
71  : LLVMTargetMachine(T, TT),
72    Subtarget(TT, FS, is64Bit),
73    DataLayout(Subtarget.getDataLayout()),
74    FrameInfo(TargetFrameInfo::StackGrowsDown,
75              Subtarget.getStackAlignment(),
76              (Subtarget.isTargetWin64() ? -40 :
77               (Subtarget.is64Bit() ? -8 : -4))),
78    InstrInfo(*this), JITInfo(*this), TLInfo(*this), ELFWriterInfo(*this) {
79  DefRelocModel = getRelocationModel();
80
81  // If no relocation model was picked, default as appropriate for the target.
82  if (getRelocationModel() == Reloc::Default) {
83    if (!Subtarget.isTargetDarwin())
84      setRelocationModel(Reloc::Static);
85    else if (Subtarget.is64Bit())
86      setRelocationModel(Reloc::PIC_);
87    else
88      setRelocationModel(Reloc::DynamicNoPIC);
89  }
90
91  assert(getRelocationModel() != Reloc::Default &&
92         "Relocation mode not picked");
93
94  // ELF and X86-64 don't have a distinct DynamicNoPIC model.  DynamicNoPIC
95  // is defined as a model for code which may be used in static or dynamic
96  // executables but not necessarily a shared library. On X86-32 we just
97  // compile in -static mode, in x86-64 we use PIC.
98  if (getRelocationModel() == Reloc::DynamicNoPIC) {
99    if (is64Bit)
100      setRelocationModel(Reloc::PIC_);
101    else if (!Subtarget.isTargetDarwin())
102      setRelocationModel(Reloc::Static);
103  }
104
105  // If we are on Darwin, disallow static relocation model in X86-64 mode, since
106  // the Mach-O file format doesn't support it.
107  if (getRelocationModel() == Reloc::Static &&
108      Subtarget.isTargetDarwin() &&
109      is64Bit)
110    setRelocationModel(Reloc::PIC_);
111
112  // Determine the PICStyle based on the target selected.
113  if (getRelocationModel() == Reloc::Static) {
114    // Unless we're in PIC or DynamicNoPIC mode, set the PIC style to None.
115    Subtarget.setPICStyle(PICStyles::None);
116  } else if (Subtarget.isTargetCygMing()) {
117    Subtarget.setPICStyle(PICStyles::None);
118  } else if (Subtarget.isTargetDarwin()) {
119    if (Subtarget.is64Bit())
120      Subtarget.setPICStyle(PICStyles::RIPRel);
121    else if (getRelocationModel() == Reloc::PIC_)
122      Subtarget.setPICStyle(PICStyles::StubPIC);
123    else {
124      assert(getRelocationModel() == Reloc::DynamicNoPIC);
125      Subtarget.setPICStyle(PICStyles::StubDynamicNoPIC);
126    }
127  } else if (Subtarget.isTargetELF()) {
128    if (Subtarget.is64Bit())
129      Subtarget.setPICStyle(PICStyles::RIPRel);
130    else
131      Subtarget.setPICStyle(PICStyles::GOT);
132  }
133
134  // Finally, if we have "none" as our PIC style, force to static mode.
135  if (Subtarget.getPICStyle() == PICStyles::None)
136    setRelocationModel(Reloc::Static);
137}
138
139//===----------------------------------------------------------------------===//
140// Pass Pipeline Configuration
141//===----------------------------------------------------------------------===//
142
143bool X86TargetMachine::addInstSelector(PassManagerBase &PM,
144                                       CodeGenOpt::Level OptLevel) {
145  // Install an instruction selector.
146  PM.add(createX86ISelDag(*this, OptLevel));
147
148  // If we're using Fast-ISel, clean up the mess.
149  if (EnableFastISel)
150    PM.add(createDeadMachineInstructionElimPass());
151
152  // Install a pass to insert x87 FP_REG_KILL instructions, as needed.
153  PM.add(createX87FPRegKillInserterPass());
154
155  return false;
156}
157
158bool X86TargetMachine::addPreRegAlloc(PassManagerBase &PM,
159                                      CodeGenOpt::Level OptLevel) {
160  return false;  // -print-machineinstr shouldn't print after this.
161}
162
163bool X86TargetMachine::addPostRegAlloc(PassManagerBase &PM,
164                                       CodeGenOpt::Level OptLevel) {
165  PM.add(createX86FloatingPointStackifierPass());
166  return true;  // -print-machineinstr should print after this.
167}
168
169bool X86TargetMachine::addCodeEmitter(PassManagerBase &PM,
170                                      CodeGenOpt::Level OptLevel,
171                                      MachineCodeEmitter &MCE) {
172  // FIXME: Move this to TargetJITInfo!
173  // On Darwin, do not override 64-bit setting made in X86TargetMachine().
174  if (DefRelocModel == Reloc::Default &&
175      (!Subtarget.isTargetDarwin() || !Subtarget.is64Bit())) {
176    setRelocationModel(Reloc::Static);
177    Subtarget.setPICStyle(PICStyles::None);
178  }
179
180  PM.add(createX86CodeEmitterPass(*this, MCE));
181
182  return false;
183}
184
185bool X86TargetMachine::addCodeEmitter(PassManagerBase &PM,
186                                      CodeGenOpt::Level OptLevel,
187                                      JITCodeEmitter &JCE) {
188  // FIXME: Move this to TargetJITInfo!
189  // On Darwin, do not override 64-bit setting made in X86TargetMachine().
190  if (DefRelocModel == Reloc::Default &&
191      (!Subtarget.isTargetDarwin() || !Subtarget.is64Bit())) {
192    setRelocationModel(Reloc::Static);
193    Subtarget.setPICStyle(PICStyles::None);
194  }
195
196
197  PM.add(createX86JITCodeEmitterPass(*this, JCE));
198
199  return false;
200}
201
202bool X86TargetMachine::addCodeEmitter(PassManagerBase &PM,
203                                      CodeGenOpt::Level OptLevel,
204                                      ObjectCodeEmitter &OCE) {
205  PM.add(createX86ObjectCodeEmitterPass(*this, OCE));
206  return false;
207}
208
209bool X86TargetMachine::addSimpleCodeEmitter(PassManagerBase &PM,
210                                            CodeGenOpt::Level OptLevel,
211                                            MachineCodeEmitter &MCE) {
212  PM.add(createX86CodeEmitterPass(*this, MCE));
213  return false;
214}
215
216bool X86TargetMachine::addSimpleCodeEmitter(PassManagerBase &PM,
217                                            CodeGenOpt::Level OptLevel,
218                                            JITCodeEmitter &JCE) {
219  PM.add(createX86JITCodeEmitterPass(*this, JCE));
220  return false;
221}
222
223bool X86TargetMachine::addSimpleCodeEmitter(PassManagerBase &PM,
224                                            CodeGenOpt::Level OptLevel,
225                                            ObjectCodeEmitter &OCE) {
226  PM.add(createX86ObjectCodeEmitterPass(*this, OCE));
227  return false;
228}
229
230void X86TargetMachine::setCodeModelForStatic() {
231
232    if (getCodeModel() != CodeModel::Default) return;
233
234    // For static codegen, if we're not already set, use Small codegen.
235    setCodeModel(CodeModel::Small);
236}
237
238
239void X86TargetMachine::setCodeModelForJIT() {
240
241  if (getCodeModel() != CodeModel::Default) return;
242
243  // 64-bit JIT places everything in the same buffer except external functions.
244  if (Subtarget.is64Bit())
245    setCodeModel(CodeModel::Large);
246  else
247    setCodeModel(CodeModel::Small);
248}
249
250/// getLSDAEncoding - Returns the LSDA pointer encoding. The choices are 4-byte,
251/// 8-byte, and target default. The CIE is hard-coded to indicate that the LSDA
252/// pointer in the FDE section is an "sdata4", and should be encoded as a 4-byte
253/// pointer by default. However, some systems may require a different size due
254/// to bugs or other conditions. We will default to a 4-byte encoding unless the
255/// system tells us otherwise.
256///
257/// The issue is when the CIE says their is an LSDA. That mandates that every
258/// FDE have an LSDA slot. But if the function does not need an LSDA. There
259/// needs to be some way to signify there is none. The LSDA is encoded as
260/// pc-rel. But you don't look for some magic value after adding the pc. You
261/// have to look for a zero before adding the pc. The problem is that the size
262/// of the zero to look for depends on the encoding. The unwinder bug in SL is
263/// that it always checks for a pointer-size zero. So on x86_64 it looks for 8
264/// bytes of zero. If you have an LSDA, it works fine since the 8-bytes are
265/// non-zero so it goes ahead and then reads the value based on the encoding.
266/// But if you use sdata4 and there is no LSDA, then the test for zero gives a
267/// false negative and the unwinder thinks there is an LSDA.
268///
269/// FIXME: This call-back isn't good! We should be using the correct encoding
270/// regardless of the system. However, there are some systems which have bugs
271/// that prevent this from occuring.
272DwarfLSDAEncoding::Encoding X86TargetMachine::getLSDAEncoding() const {
273  if (Subtarget.isTargetDarwin() && Subtarget.getDarwinVers() != 10)
274    return DwarfLSDAEncoding::Default;
275
276  return DwarfLSDAEncoding::EightByte;
277}
278