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 #include "X86Subtarget.h"
15 #include "X86GenSubtarget.inc"
16 #include "llvm/Module.h"
17 #include "llvm/Support/CommandLine.h"
18 #include "llvm/Target/TargetMachine.h"
19 #include "llvm/Target/TargetOptions.h"
22 static cl::opt<X86Subtarget::AsmWriterFlavorTy>
23 AsmWriterFlavor("x86-asm-syntax", cl::init(X86Subtarget::Unset),
24 cl::desc("Choose style of code to emit from X86 backend:"),
26 clEnumValN(X86Subtarget::ATT, "att", "Emit AT&T-style assembly"),
27 clEnumValN(X86Subtarget::Intel, "intel", "Emit Intel-style assembly"),
31 /// True if accessing the GV requires an extra load. For Windows, dllimported
32 /// symbols are indirect, loading the value at address GV rather then the
33 /// value of GV itself. This means that the GlobalAddress must be in the base
34 /// or index register of the address, not the GV offset field.
35 bool X86Subtarget::GVRequiresExtraLoad(const GlobalValue* GV,
36 const TargetMachine& TM,
37 bool isDirectCall) const
40 if (TM.getRelocationModel() != Reloc::Static &&
41 TM.getCodeModel() != CodeModel::Large) {
42 if (isTargetDarwin()) {
43 bool isDecl = GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode();
44 if (GV->hasHiddenVisibility() &&
45 (Is64Bit || (!isDecl && !GV->hasCommonLinkage())))
46 // If symbol visibility is hidden, the extra load is not needed if
47 // target is x86-64 or the symbol is definitely defined in the current
50 return !isDirectCall && (isDecl || GV->mayBeOverridden());
51 } else if (isTargetELF()) {
52 // Extra load is needed for all externally visible.
55 if (GV->hasInternalLinkage() || GV->hasHiddenVisibility())
58 } else if (isTargetCygMing() || isTargetWindows()) {
59 return (GV->hasDLLImportLinkage());
65 /// True if accessing the GV requires a register. This is a superset of the
66 /// cases where GVRequiresExtraLoad is true. Some variations of PIC require
67 /// a register, but not an extra load.
68 bool X86Subtarget::GVRequiresRegister(const GlobalValue *GV,
69 const TargetMachine& TM,
70 bool isDirectCall) const
72 if (GVRequiresExtraLoad(GV, TM, isDirectCall))
74 // Code below here need only consider cases where GVRequiresExtraLoad
76 if (TM.getRelocationModel() == Reloc::PIC_)
77 return !isDirectCall &&
78 (GV->hasInternalLinkage() || GV->hasExternalLinkage());
82 /// getBZeroEntry - This function returns the name of a function which has an
83 /// interface like the non-standard bzero function, if such a function exists on
84 /// the current subtarget and it is considered prefereable over memset with zero
85 /// passed as the second argument. Otherwise it returns null.
86 const char *X86Subtarget::getBZeroEntry() const {
87 // Darwin 10 has a __bzero entry point for this purpose.
88 if (getDarwinVers() >= 10)
94 /// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
95 /// specified arguments. If we can't run cpuid on the host, return true.
96 bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
97 unsigned *rECX, unsigned *rEDX) {
98 #if defined(__x86_64__)
99 // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
100 asm ("movq\t%%rbx, %%rsi\n\t"
102 "xchgq\t%%rbx, %%rsi\n\t"
109 #elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
110 #if defined(__GNUC__)
111 asm ("movl\t%%ebx, %%esi\n\t"
113 "xchgl\t%%ebx, %%esi\n\t"
120 #elif defined(_MSC_VER)
125 mov dword ptr [esi],eax
127 mov dword ptr [esi],ebx
129 mov dword ptr [esi],ecx
131 mov dword ptr [esi],edx
139 void X86Subtarget::AutoDetectSubtargetFeatures() {
140 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
146 if (X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
149 X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
151 if ((EDX >> 23) & 0x1) X86SSELevel = MMX;
152 if ((EDX >> 25) & 0x1) X86SSELevel = SSE1;
153 if ((EDX >> 26) & 0x1) X86SSELevel = SSE2;
154 if (ECX & 0x1) X86SSELevel = SSE3;
155 if ((ECX >> 9) & 0x1) X86SSELevel = SSSE3;
156 if ((ECX >> 19) & 0x1) X86SSELevel = SSE41;
157 if ((ECX >> 20) & 0x1) X86SSELevel = SSE42;
159 if (memcmp(text.c, "GenuineIntel", 12) == 0 ||
160 memcmp(text.c, "AuthenticAMD", 12) == 0) {
161 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
162 HasX86_64 = (EDX >> 29) & 0x1;
166 static const char *GetCurrentX86CPU() {
167 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
168 if (X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
170 unsigned Family = (EAX >> 8) & 0xf; // Bits 8 - 11
171 unsigned Model = (EAX >> 4) & 0xf; // Bits 4 - 7
172 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
173 bool Em64T = (EDX >> 29) & 0x1;
180 X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1);
181 if (memcmp(text.c, "GenuineIntel", 12) == 0) {
189 case 4: return "pentium-mmx";
190 default: return "pentium";
194 case 1: return "pentiumpro";
197 case 6: return "pentium2";
201 case 11: return "pentium3";
203 case 13: return "pentium-m";
204 case 14: return "yonah";
205 case 15: return "core2";
206 default: return "i686";
212 return (Em64T) ? "nocona" : "prescott";
214 return (Em64T) ? "x86-64" : "pentium4";
221 } else if (memcmp(text.c, "AuthenticAMD", 12) == 0) {
222 // FIXME: this poorly matches the generated SubtargetFeatureKV table. There
223 // appears to be no way to generate the wide variety of AMD-specific targets
224 // from the information returned from CPUID.
232 case 8: return "k6-2";
234 case 13: return "k6-3";
235 default: return "pentium";
239 case 4: return "athlon-tbird";
242 case 8: return "athlon-mp";
243 case 10: return "athlon-xp";
244 default: return "athlon";
248 case 1: return "opteron";
249 case 5: return "athlon-fx"; // also opteron
250 default: return "athlon64";
260 X86Subtarget::X86Subtarget(const Module &M, const std::string &FS, bool is64Bit)
261 : AsmFlavor(AsmWriterFlavor)
262 , PICStyle(PICStyles::None)
263 , X86SSELevel(NoMMXSSE)
264 , X863DNowLevel(NoThreeDNow)
269 // FIXME: this is a known good value for Yonah. How about others?
270 , MaxInlineSizeThreshold(128)
272 , TargetType(isELF) { // Default to ELF unless otherwise specified.
274 // Determine default and user specified characteristics
276 // If feature string is not empty, parse features string.
277 std::string CPU = GetCurrentX86CPU();
278 ParseSubtargetFeatures(FS, CPU);
280 // Otherwise, use CPUID to auto-detect feature set.
281 AutoDetectSubtargetFeatures();
284 // If requesting codegen for X86-64, make sure that 64-bit and SSE2 features
285 // are enabled. These are available on all x86-64 CPUs.
288 if (X86SSELevel < SSE2)
292 // Set the boolean corresponding to the current target triple, or the default
293 // if one cannot be determined, to true.
294 const std::string& TT = M.getTargetTriple();
295 if (TT.length() > 5) {
297 if ((Pos = TT.find("-darwin")) != std::string::npos) {
298 TargetType = isDarwin;
300 // Compute the darwin version number.
301 if (isdigit(TT[Pos+7]))
302 DarwinVers = atoi(&TT[Pos+7]);
304 DarwinVers = 8; // Minimum supported darwin is Tiger.
305 } else if (TT.find("linux") != std::string::npos) {
306 // Linux doesn't imply ELF, but we don't currently support anything else.
309 } else if (TT.find("cygwin") != std::string::npos) {
310 TargetType = isCygwin;
311 } else if (TT.find("mingw") != std::string::npos) {
312 TargetType = isMingw;
313 } else if (TT.find("win32") != std::string::npos) {
314 TargetType = isWindows;
315 } else if (TT.find("windows") != std::string::npos) {
316 TargetType = isWindows;
318 } else if (TT.empty()) {
319 #if defined(__CYGWIN__)
320 TargetType = isCygwin;
321 #elif defined(__MINGW32__) || defined(__MINGW64__)
322 TargetType = isMingw;
323 #elif defined(__APPLE__)
324 TargetType = isDarwin;
325 #if __APPLE_CC__ > 5400
326 DarwinVers = 9; // GCC 5400+ is Leopard.
328 DarwinVers = 8; // Minimum supported darwin is Tiger.
331 #elif defined(_WIN32) || defined(_WIN64)
332 TargetType = isWindows;
333 #elif defined(__linux__)
334 // Linux doesn't imply ELF, but we don't currently support anything else.
340 // If the asm syntax hasn't been overridden on the command line, use whatever
342 if (AsmFlavor == X86Subtarget::Unset) {
343 AsmFlavor = (TargetType == isWindows)
344 ? X86Subtarget::Intel : X86Subtarget::ATT;
347 // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
349 if (TargetType == isDarwin || Is64Bit)
353 stackAlignment = StackAlignment;