1 //===-- X86Subtarget.cpp - X86 Subtarget Information ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the X86 specific subclass of TargetSubtarget.
12 //===----------------------------------------------------------------------===//
14 #define DEBUG_TYPE "subtarget"
15 #include "X86Subtarget.h"
16 #include "X86GenSubtarget.inc"
17 #include "llvm/Module.h"
18 #include "llvm/Support/CommandLine.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Target/TargetMachine.h"
21 #include "llvm/Target/TargetOptions.h"
28 static cl::opt<X86Subtarget::AsmWriterFlavorTy>
29 AsmWriterFlavor("x86-asm-syntax", cl::init(X86Subtarget::Unset),
30 cl::desc("Choose style of code to emit from X86 backend:"),
32 clEnumValN(X86Subtarget::ATT, "att", "Emit AT&T-style assembly"),
33 clEnumValN(X86Subtarget::Intel, "intel", "Emit Intel-style assembly"),
37 /// True if accessing the GV requires an extra load. For Windows, dllimported
38 /// symbols are indirect, loading the value at address GV rather then the
39 /// value of GV itself. This means that the GlobalAddress must be in the base
40 /// or index register of the address, not the GV offset field.
41 bool X86Subtarget::GVRequiresExtraLoad(const GlobalValue* GV,
42 const TargetMachine& TM,
43 bool isDirectCall) const
46 if (TM.getRelocationModel() != Reloc::Static &&
47 TM.getCodeModel() != CodeModel::Large) {
48 if (isTargetDarwin()) {
51 bool isDecl = GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode();
52 if (GV->hasHiddenVisibility() &&
53 (Is64Bit || (!isDecl && !GV->hasCommonLinkage())))
54 // If symbol visibility is hidden, the extra load is not needed if
55 // target is x86-64 or the symbol is definitely defined in the current
58 return !isDirectCall && (isDecl || GV->isWeakForLinker());
59 } else if (isTargetELF()) {
60 // Extra load is needed for all externally visible.
63 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
66 } else if (isTargetCygMing() || isTargetWindows()) {
67 return (GV->hasDLLImportLinkage());
73 /// True if accessing the GV requires a register. This is a superset of the
74 /// cases where GVRequiresExtraLoad is true. Some variations of PIC require
75 /// a register, but not an extra load.
76 bool X86Subtarget::GVRequiresRegister(const GlobalValue *GV,
77 const TargetMachine& TM,
78 bool isDirectCall) const
80 if (GVRequiresExtraLoad(GV, TM, isDirectCall))
82 // Code below here need only consider cases where GVRequiresExtraLoad
84 if (TM.getRelocationModel() == Reloc::PIC_)
85 return !isDirectCall &&
86 (GV->hasLocalLinkage() || GV->hasExternalLinkage());
90 /// getBZeroEntry - This function returns the name of a function which has an
91 /// interface like the non-standard bzero function, if such a function exists on
92 /// the current subtarget and it is considered prefereable over memset with zero
93 /// passed as the second argument. Otherwise it returns null.
94 const char *X86Subtarget::getBZeroEntry() const {
95 // Darwin 10 has a __bzero entry point for this purpose.
96 if (getDarwinVers() >= 10)
102 /// IsLegalToCallImmediateAddr - Return true if the subtarget allows calls
103 /// to immediate address.
104 bool X86Subtarget::IsLegalToCallImmediateAddr(const TargetMachine &TM) const {
107 return isTargetELF() || TM.getRelocationModel() == Reloc::Static;
110 /// getSpecialAddressLatency - For targets where it is beneficial to
111 /// backschedule instructions that compute addresses, return a value
112 /// indicating the number of scheduling cycles of backscheduling that
113 /// should be attempted.
114 unsigned X86Subtarget::getSpecialAddressLatency() const {
115 // For x86 out-of-order targets, back-schedule address computations so
116 // that loads and stores aren't blocked.
117 // This value was chosen arbitrarily.
121 /// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
122 /// specified arguments. If we can't run cpuid on the host, return true.
123 bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
124 unsigned *rECX, unsigned *rEDX) {
125 #if defined(__x86_64__) || defined(_M_AMD64)
126 #if defined(__GNUC__)
127 // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
128 asm ("movq\t%%rbx, %%rsi\n\t"
130 "xchgq\t%%rbx, %%rsi\n\t"
137 #elif defined(_MSC_VER)
139 __cpuid(registers, value);
140 *rEAX = registers[0];
141 *rEBX = registers[1];
142 *rECX = registers[2];
143 *rEDX = registers[3];
146 #elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
147 #if defined(__GNUC__)
148 asm ("movl\t%%ebx, %%esi\n\t"
150 "xchgl\t%%ebx, %%esi\n\t"
157 #elif defined(_MSC_VER)
162 mov dword ptr [esi],eax
164 mov dword ptr [esi],ebx
166 mov dword ptr [esi],ecx
168 mov dword ptr [esi],edx
176 static void DetectFamilyModel(unsigned EAX, unsigned &Family, unsigned &Model) {
177 Family = (EAX >> 8) & 0xf; // Bits 8 - 11
178 Model = (EAX >> 4) & 0xf; // Bits 4 - 7
179 if (Family == 6 || Family == 0xf) {
181 // Examine extended family ID if family ID is F.
182 Family += (EAX >> 20) & 0xff; // Bits 20 - 27
183 // Examine extended model ID if family ID is 6 or F.
184 Model += ((EAX >> 16) & 0xf) << 4; // Bits 16 - 19
188 void X86Subtarget::AutoDetectSubtargetFeatures() {
189 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
195 if (X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
198 X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
200 if ((EDX >> 23) & 0x1) X86SSELevel = MMX;
201 if ((EDX >> 25) & 0x1) X86SSELevel = SSE1;
202 if ((EDX >> 26) & 0x1) X86SSELevel = SSE2;
203 if (ECX & 0x1) X86SSELevel = SSE3;
204 if ((ECX >> 9) & 0x1) X86SSELevel = SSSE3;
205 if ((ECX >> 19) & 0x1) X86SSELevel = SSE41;
206 if ((ECX >> 20) & 0x1) X86SSELevel = SSE42;
208 bool IsIntel = memcmp(text.c, "GenuineIntel", 12) == 0;
209 bool IsAMD = !IsIntel && memcmp(text.c, "AuthenticAMD", 12) == 0;
210 if (IsIntel || IsAMD) {
211 // Determine if bit test memory instructions are slow.
214 DetectFamilyModel(EAX, Family, Model);
215 IsBTMemSlow = IsAMD || (Family == 6 && Model >= 13);
217 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
218 HasX86_64 = (EDX >> 29) & 0x1;
222 static const char *GetCurrentX86CPU() {
223 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
224 if (X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
228 DetectFamilyModel(EAX, Family, Model);
230 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
231 bool Em64T = (EDX >> 29) & 0x1;
238 X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1);
239 if (memcmp(text.c, "GenuineIntel", 12) == 0) {
247 case 4: return "pentium-mmx";
248 default: return "pentium";
252 case 1: return "pentiumpro";
255 case 6: return "pentium2";
259 case 11: return "pentium3";
261 case 13: return "pentium-m";
262 case 14: return "yonah";
264 case 22: // Celeron M 540
266 case 23: // 45nm: Penryn , Wolfdale, Yorkfield (XE)
268 default: return "i686";
274 case 6: // same as 4, but 65nm
275 return (Em64T) ? "nocona" : "prescott";
281 return (Em64T) ? "x86-64" : "pentium4";
288 } else if (memcmp(text.c, "AuthenticAMD", 12) == 0) {
289 // FIXME: this poorly matches the generated SubtargetFeatureKV table. There
290 // appears to be no way to generate the wide variety of AMD-specific targets
291 // from the information returned from CPUID.
299 case 8: return "k6-2";
301 case 13: return "k6-3";
302 default: return "pentium";
306 case 4: return "athlon-tbird";
309 case 8: return "athlon-mp";
310 case 10: return "athlon-xp";
311 default: return "athlon";
315 case 1: return "opteron";
316 case 5: return "athlon-fx"; // also opteron
317 default: return "athlon64";
327 X86Subtarget::X86Subtarget(const Module &M, const std::string &FS, bool is64Bit)
328 : AsmFlavor(AsmWriterFlavor)
329 , PICStyle(PICStyles::None)
330 , X86SSELevel(NoMMXSSE)
331 , X863DNowLevel(NoThreeDNow)
337 // FIXME: this is a known good value for Yonah. How about others?
338 , MaxInlineSizeThreshold(128)
340 , TargetType(isELF) { // Default to ELF unless otherwise specified.
342 // Determine default and user specified characteristics
344 // If feature string is not empty, parse features string.
345 std::string CPU = GetCurrentX86CPU();
346 ParseSubtargetFeatures(FS, CPU);
347 // All X86-64 CPUs also have SSE2, however user might request no SSE via
348 // -mattr, so don't force SSELevel here.
350 // Otherwise, use CPUID to auto-detect feature set.
351 AutoDetectSubtargetFeatures();
352 // Make sure SSE2 is enabled; it is available on all X86-64 CPUs.
353 if (Is64Bit && X86SSELevel < SSE2)
357 // If requesting codegen for X86-64, make sure that 64-bit features
362 DOUT << "Subtarget features: SSELevel " << X86SSELevel
363 << ", 3DNowLevel " << X863DNowLevel
364 << ", 64bit " << HasX86_64 << "\n";
365 assert((!Is64Bit || HasX86_64) &&
366 "64-bit code requested on a subtarget that doesn't support it!");
368 // Set the boolean corresponding to the current target triple, or the default
369 // if one cannot be determined, to true.
370 const std::string& TT = M.getTargetTriple();
371 if (TT.length() > 5) {
373 if ((Pos = TT.find("-darwin")) != std::string::npos) {
374 TargetType = isDarwin;
376 // Compute the darwin version number.
377 if (isdigit(TT[Pos+7]))
378 DarwinVers = atoi(&TT[Pos+7]);
380 DarwinVers = 8; // Minimum supported darwin is Tiger.
381 } else if (TT.find("linux") != std::string::npos) {
382 // Linux doesn't imply ELF, but we don't currently support anything else.
385 } else if (TT.find("cygwin") != std::string::npos) {
386 TargetType = isCygwin;
387 } else if (TT.find("mingw") != std::string::npos) {
388 TargetType = isMingw;
389 } else if (TT.find("win32") != std::string::npos) {
390 TargetType = isWindows;
391 } else if (TT.find("windows") != std::string::npos) {
392 TargetType = isWindows;
394 else if (TT.find("-cl") != std::string::npos) {
395 TargetType = isDarwin;
398 } else if (TT.empty()) {
399 #if defined(__CYGWIN__)
400 TargetType = isCygwin;
401 #elif defined(__MINGW32__) || defined(__MINGW64__)
402 TargetType = isMingw;
403 #elif defined(__APPLE__)
404 TargetType = isDarwin;
405 #if __APPLE_CC__ > 5400
406 DarwinVers = 9; // GCC 5400+ is Leopard.
408 DarwinVers = 8; // Minimum supported darwin is Tiger.
411 #elif defined(_WIN32) || defined(_WIN64)
412 TargetType = isWindows;
413 #elif defined(__linux__)
414 // Linux doesn't imply ELF, but we don't currently support anything else.
420 // If the asm syntax hasn't been overridden on the command line, use whatever
422 if (AsmFlavor == X86Subtarget::Unset) {
423 AsmFlavor = (TargetType == isWindows)
424 ? X86Subtarget::Intel : X86Subtarget::ATT;
427 // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
429 if (TargetType == isDarwin || Is64Bit)
433 stackAlignment = StackAlignment;