1 //===-- X86Subtarget.cpp - X86 Subtarget Information ----------------------===//
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 implements the X86 specific subclass of TargetSubtargetInfo.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "X86Subtarget.h"
15 #include "X86InstrInfo.h"
16 #include "X86TargetMachine.h"
17 #include "llvm/IR/Attributes.h"
18 #include "llvm/IR/Function.h"
19 #include "llvm/IR/GlobalValue.h"
20 #include "llvm/Support/CommandLine.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Support/ErrorHandling.h"
23 #include "llvm/Support/Host.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include "llvm/Target/TargetMachine.h"
26 #include "llvm/Target/TargetOptions.h"
27 
28 #if defined(_MSC_VER)
29 #include <intrin.h>
30 #endif
31 
32 using namespace llvm;
33 
34 #define DEBUG_TYPE "subtarget"
35 
36 #define GET_SUBTARGETINFO_TARGET_DESC
37 #define GET_SUBTARGETINFO_CTOR
38 #include "X86GenSubtargetInfo.inc"
39 
40 // Temporary option to control early if-conversion for x86 while adding machine
41 // models.
42 static cl::opt<bool>
43 X86EarlyIfConv("x86-early-ifcvt", cl::Hidden,
44                cl::desc("Enable early if-conversion on X86"));
45 
46 
47 /// ClassifyBlockAddressReference - Classify a blockaddress reference for the
48 /// current subtarget according to how we should reference it in a non-pcrel
49 /// context.
50 unsigned char X86Subtarget::ClassifyBlockAddressReference() const {
51   if (isPICStyleGOT())    // 32-bit ELF targets.
52     return X86II::MO_GOTOFF;
53 
54   if (isPICStyleStubPIC())   // Darwin/32 in PIC mode.
55     return X86II::MO_PIC_BASE_OFFSET;
56 
57   // Direct static reference to label.
58   return X86II::MO_NO_FLAG;
59 }
60 
61 /// ClassifyGlobalReference - Classify a global variable reference for the
62 /// current subtarget according to how we should reference it in a non-pcrel
63 /// context.
64 unsigned char X86Subtarget::
65 ClassifyGlobalReference(const GlobalValue *GV, const TargetMachine &TM) const {
66   // DLLImport only exists on windows, it is implemented as a load from a
67   // DLLIMPORT stub.
68   if (GV->hasDLLImportStorageClass())
69     return X86II::MO_DLLIMPORT;
70 
71   bool isDef = GV->isStrongDefinitionForLinker();
72 
73   // X86-64 in PIC mode.
74   if (isPICStyleRIPRel()) {
75     // Large model never uses stubs.
76     if (TM.getCodeModel() == CodeModel::Large)
77       return X86II::MO_NO_FLAG;
78 
79     if (isTargetDarwin()) {
80       // If symbol visibility is hidden, the extra load is not needed if
81       // target is x86-64 or the symbol is definitely defined in the current
82       // translation unit.
83       if (GV->hasDefaultVisibility() && !isDef)
84         return X86II::MO_GOTPCREL;
85     } else if (!isTargetWin64()) {
86       assert(isTargetELF() && "Unknown rip-relative target");
87 
88       // Extra load is needed for all externally visible.
89       if (!GV->hasLocalLinkage() && GV->hasDefaultVisibility())
90         return X86II::MO_GOTPCREL;
91     }
92 
93     return X86II::MO_NO_FLAG;
94   }
95 
96   if (isPICStyleGOT()) {   // 32-bit ELF targets.
97     // Extra load is needed for all externally visible.
98     if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
99       return X86II::MO_GOTOFF;
100     return X86II::MO_GOT;
101   }
102 
103   if (isPICStyleStubPIC()) {  // Darwin/32 in PIC mode.
104     // Determine whether we have a stub reference and/or whether the reference
105     // is relative to the PIC base or not.
106 
107     // If this is a strong reference to a definition, it is definitely not
108     // through a stub.
109     if (isDef)
110       return X86II::MO_PIC_BASE_OFFSET;
111 
112     // Unless we have a symbol with hidden visibility, we have to go through a
113     // normal $non_lazy_ptr stub because this symbol might be resolved late.
114     if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
115       return X86II::MO_DARWIN_NONLAZY_PIC_BASE;
116 
117     // If symbol visibility is hidden, we have a stub for common symbol
118     // references and external declarations.
119     if (GV->isDeclarationForLinker() || GV->hasCommonLinkage()) {
120       // Hidden $non_lazy_ptr reference.
121       return X86II::MO_DARWIN_HIDDEN_NONLAZY_PIC_BASE;
122     }
123 
124     // Otherwise, no stub.
125     return X86II::MO_PIC_BASE_OFFSET;
126   }
127 
128   if (isPICStyleStubNoDynamic()) {  // Darwin/32 in -mdynamic-no-pic mode.
129     // Determine whether we have a stub reference.
130 
131     // If this is a strong reference to a definition, it is definitely not
132     // through a stub.
133     if (isDef)
134       return X86II::MO_NO_FLAG;
135 
136     // Unless we have a symbol with hidden visibility, we have to go through a
137     // normal $non_lazy_ptr stub because this symbol might be resolved late.
138     if (!GV->hasHiddenVisibility())  // Non-hidden $non_lazy_ptr reference.
139       return X86II::MO_DARWIN_NONLAZY;
140 
141     // Otherwise, no stub.
142     return X86II::MO_NO_FLAG;
143   }
144 
145   // Direct static reference to global.
146   return X86II::MO_NO_FLAG;
147 }
148 
149 
150 /// getBZeroEntry - This function returns the name of a function which has an
151 /// interface like the non-standard bzero function, if such a function exists on
152 /// the current subtarget and it is considered prefereable over memset with zero
153 /// passed as the second argument. Otherwise it returns null.
154 const char *X86Subtarget::getBZeroEntry() const {
155   // Darwin 10 has a __bzero entry point for this purpose.
156   if (getTargetTriple().isMacOSX() &&
157       !getTargetTriple().isMacOSXVersionLT(10, 6))
158     return "__bzero";
159 
160   return nullptr;
161 }
162 
163 bool X86Subtarget::hasSinCos() const {
164   return getTargetTriple().isMacOSX() &&
165     !getTargetTriple().isMacOSXVersionLT(10, 9) &&
166     is64Bit();
167 }
168 
169 /// IsLegalToCallImmediateAddr - Return true if the subtarget allows calls
170 /// to immediate address.
171 bool X86Subtarget::IsLegalToCallImmediateAddr(const TargetMachine &TM) const {
172   // FIXME: I386 PE/COFF supports PC relative calls using IMAGE_REL_I386_REL32
173   // but WinCOFFObjectWriter::RecordRelocation cannot emit them.  Once it does,
174   // the following check for Win32 should be removed.
175   if (In64BitMode || isTargetWin32())
176     return false;
177   return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
178 }
179 
180 void X86Subtarget::initSubtargetFeatures(StringRef CPU, StringRef FS) {
181   std::string CPUName = CPU;
182   if (CPUName.empty())
183     CPUName = "generic";
184 
185   // Make sure 64-bit features are available in 64-bit mode. (But make sure
186   // SSE2 can be turned off explicitly.)
187   std::string FullFS = FS;
188   if (In64BitMode) {
189     if (!FullFS.empty())
190       FullFS = "+64bit,+sse2," + FullFS;
191     else
192       FullFS = "+64bit,+sse2";
193   }
194 
195   // If feature string is not empty, parse features string.
196   ParseSubtargetFeatures(CPUName, FullFS);
197 
198   // Make sure the right MCSchedModel is used.
199   InitCPUSchedModel(CPUName);
200 
201   InstrItins = getInstrItineraryForCPU(CPUName);
202 
203   // It's important to keep the MCSubtargetInfo feature bits in sync with
204   // target data structure which is shared with MC code emitter, etc.
205   if (In64BitMode)
206     ToggleFeature(X86::Mode64Bit);
207   else if (In32BitMode)
208     ToggleFeature(X86::Mode32Bit);
209   else if (In16BitMode)
210     ToggleFeature(X86::Mode16Bit);
211   else
212     llvm_unreachable("Not 16-bit, 32-bit or 64-bit mode!");
213 
214   DEBUG(dbgs() << "Subtarget features: SSELevel " << X86SSELevel
215                << ", 3DNowLevel " << X863DNowLevel
216                << ", 64bit " << HasX86_64 << "\n");
217   assert((!In64BitMode || HasX86_64) &&
218          "64-bit code requested on a subtarget that doesn't support it!");
219 
220   // Stack alignment is 16 bytes on Darwin, Linux and Solaris (both
221   // 32 and 64 bit) and for all 64-bit targets.
222   if (StackAlignOverride)
223     stackAlignment = StackAlignOverride;
224   else if (isTargetDarwin() || isTargetLinux() || isTargetSolaris() ||
225            In64BitMode)
226     stackAlignment = 16;
227 }
228 
229 void X86Subtarget::initializeEnvironment() {
230   X86SSELevel = NoMMXSSE;
231   X863DNowLevel = NoThreeDNow;
232   HasCMov = false;
233   HasX86_64 = false;
234   HasPOPCNT = false;
235   HasSSE4A = false;
236   HasAES = false;
237   HasPCLMUL = false;
238   HasFMA = false;
239   HasFMA4 = false;
240   HasXOP = false;
241   HasTBM = false;
242   HasMOVBE = false;
243   HasRDRAND = false;
244   HasF16C = false;
245   HasFSGSBase = false;
246   HasLZCNT = false;
247   HasBMI = false;
248   HasBMI2 = false;
249   HasRTM = false;
250   HasHLE = false;
251   HasERI = false;
252   HasCDI = false;
253   HasPFI = false;
254   HasDQI = false;
255   HasBWI = false;
256   HasVLX = false;
257   HasADX = false;
258   HasSHA = false;
259   HasPRFCHW = false;
260   HasRDSEED = false;
261   HasMPX = false;
262   IsBTMemSlow = false;
263   IsSHLDSlow = false;
264   IsUAMemFast = false;
265   IsUAMem32Slow = false;
266   HasSSEUnalignedMem = false;
267   HasCmpxchg16b = false;
268   UseLeaForSP = false;
269   HasSlowDivide32 = false;
270   HasSlowDivide64 = false;
271   PadShortFunctions = false;
272   CallRegIndirect = false;
273   LEAUsesAG = false;
274   SlowLEA = false;
275   SlowIncDec = false;
276   stackAlignment = 4;
277   // FIXME: this is a known good value for Yonah. How about others?
278   MaxInlineSizeThreshold = 128;
279   UseSoftFloat = false;
280 }
281 
282 X86Subtarget &X86Subtarget::initializeSubtargetDependencies(StringRef CPU,
283                                                             StringRef FS) {
284   initializeEnvironment();
285   initSubtargetFeatures(CPU, FS);
286   return *this;
287 }
288 
289 X86Subtarget::X86Subtarget(const Triple &TT, const std::string &CPU,
290                            const std::string &FS, const X86TargetMachine &TM,
291                            unsigned StackAlignOverride)
292     : X86GenSubtargetInfo(TT, CPU, FS), X86ProcFamily(Others),
293       PICStyle(PICStyles::None), TargetTriple(TT),
294       StackAlignOverride(StackAlignOverride),
295       In64BitMode(TargetTriple.getArch() == Triple::x86_64),
296       In32BitMode(TargetTriple.getArch() == Triple::x86 &&
297                   TargetTriple.getEnvironment() != Triple::CODE16),
298       In16BitMode(TargetTriple.getArch() == Triple::x86 &&
299                   TargetTriple.getEnvironment() == Triple::CODE16),
300       TSInfo(), InstrInfo(initializeSubtargetDependencies(CPU, FS)),
301       TLInfo(TM, *this), FrameLowering(*this, getStackAlignment()) {
302   // Determine the PICStyle based on the target selected.
303   if (TM.getRelocationModel() == Reloc::Static) {
304     // Unless we're in PIC or DynamicNoPIC mode, set the PIC style to None.
305     setPICStyle(PICStyles::None);
306   } else if (is64Bit()) {
307     // PIC in 64 bit mode is always rip-rel.
308     setPICStyle(PICStyles::RIPRel);
309   } else if (isTargetCOFF()) {
310     setPICStyle(PICStyles::None);
311   } else if (isTargetDarwin()) {
312     if (TM.getRelocationModel() == Reloc::PIC_)
313       setPICStyle(PICStyles::StubPIC);
314     else {
315       assert(TM.getRelocationModel() == Reloc::DynamicNoPIC);
316       setPICStyle(PICStyles::StubDynamicNoPIC);
317     }
318   } else if (isTargetELF()) {
319     setPICStyle(PICStyles::GOT);
320   }
321 }
322 
323 bool X86Subtarget::enableEarlyIfConversion() const {
324   return hasCMov() && X86EarlyIfConv;
325 }
326 
327