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());
66 /// getBZeroEntry - This function returns the name of a function which has an
67 /// interface like the non-standard bzero function, if such a function exists on
68 /// the current subtarget and it is considered prefereable over memset with zero
69 /// passed as the second argument. Otherwise it returns null.
70 const char *X86Subtarget::getBZeroEntry() const {
71 // Darwin 10 has a __bzero entry point for this purpose.
72 if (getDarwinVers() >= 10)
78 /// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
79 /// specified arguments. If we can't run cpuid on the host, return true.
80 bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
81 unsigned *rECX, unsigned *rEDX) {
82 #if defined(__x86_64__)
83 // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
84 asm ("movq\t%%rbx, %%rsi\n\t"
86 "xchgq\t%%rbx, %%rsi\n\t"
93 #elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
95 asm ("movl\t%%ebx, %%esi\n\t"
97 "xchgl\t%%ebx, %%esi\n\t"
104 #elif defined(_MSC_VER)
109 mov dword ptr [esi],eax
111 mov dword ptr [esi],ebx
113 mov dword ptr [esi],ecx
115 mov dword ptr [esi],edx
123 void X86Subtarget::AutoDetectSubtargetFeatures() {
124 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
130 if (X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
133 X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
135 if ((EDX >> 23) & 0x1) X86SSELevel = MMX;
136 if ((EDX >> 25) & 0x1) X86SSELevel = SSE1;
137 if ((EDX >> 26) & 0x1) X86SSELevel = SSE2;
138 if (ECX & 0x1) X86SSELevel = SSE3;
139 if ((ECX >> 9) & 0x1) X86SSELevel = SSSE3;
140 if ((ECX >> 19) & 0x1) X86SSELevel = SSE41;
141 if ((ECX >> 20) & 0x1) X86SSELevel = SSE42;
143 if (memcmp(text.c, "GenuineIntel", 12) == 0 ||
144 memcmp(text.c, "AuthenticAMD", 12) == 0) {
145 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
146 HasX86_64 = (EDX >> 29) & 0x1;
150 static const char *GetCurrentX86CPU() {
151 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
152 if (X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
154 unsigned Family = (EAX >> 8) & 0xf; // Bits 8 - 11
155 unsigned Model = (EAX >> 4) & 0xf; // Bits 4 - 7
156 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
157 bool Em64T = (EDX >> 29) & 0x1;
164 X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1);
165 if (memcmp(text.c, "GenuineIntel", 12) == 0) {
173 case 4: return "pentium-mmx";
174 default: return "pentium";
178 case 1: return "pentiumpro";
181 case 6: return "pentium2";
185 case 11: return "pentium3";
187 case 13: return "pentium-m";
188 case 14: return "yonah";
189 case 15: return "core2";
190 default: return "i686";
196 return (Em64T) ? "nocona" : "prescott";
198 return (Em64T) ? "x86-64" : "pentium4";
205 } else if (memcmp(text.c, "AuthenticAMD", 12) == 0) {
206 // FIXME: this poorly matches the generated SubtargetFeatureKV table. There
207 // appears to be no way to generate the wide variety of AMD-specific targets
208 // from the information returned from CPUID.
216 case 8: return "k6-2";
218 case 13: return "k6-3";
219 default: return "pentium";
223 case 4: return "athlon-tbird";
226 case 8: return "athlon-mp";
227 case 10: return "athlon-xp";
228 default: return "athlon";
232 case 1: return "opteron";
233 case 5: return "athlon-fx"; // also opteron
234 default: return "athlon64";
244 X86Subtarget::X86Subtarget(const Module &M, const std::string &FS, bool is64Bit)
245 : AsmFlavor(AsmWriterFlavor)
246 , PICStyle(PICStyles::None)
247 , X86SSELevel(NoMMXSSE)
248 , X863DNowLevel(NoThreeDNow)
253 // FIXME: this is a known good value for Yonah. How about others?
254 , MaxInlineSizeThreshold(128)
256 , TargetType(isELF) { // Default to ELF unless otherwise specified.
258 // Determine default and user specified characteristics
260 // If feature string is not empty, parse features string.
261 std::string CPU = GetCurrentX86CPU();
262 ParseSubtargetFeatures(FS, CPU);
264 // Otherwise, use CPUID to auto-detect feature set.
265 AutoDetectSubtargetFeatures();
268 // If requesting codegen for X86-64, make sure that 64-bit and SSE2 features
269 // are enabled. These are available on all x86-64 CPUs.
272 if (X86SSELevel < SSE2)
276 // Set the boolean corresponding to the current target triple, or the default
277 // if one cannot be determined, to true.
278 const std::string& TT = M.getTargetTriple();
279 if (TT.length() > 5) {
281 if ((Pos = TT.find("-darwin")) != std::string::npos) {
282 TargetType = isDarwin;
284 // Compute the darwin version number.
285 if (isdigit(TT[Pos+7]))
286 DarwinVers = atoi(&TT[Pos+7]);
288 DarwinVers = 8; // Minimum supported darwin is Tiger.
289 } else if (TT.find("linux") != std::string::npos) {
290 // Linux doesn't imply ELF, but we don't currently support anything else.
293 } else if (TT.find("cygwin") != std::string::npos) {
294 TargetType = isCygwin;
295 } else if (TT.find("mingw") != std::string::npos) {
296 TargetType = isMingw;
297 } else if (TT.find("win32") != std::string::npos) {
298 TargetType = isWindows;
299 } else if (TT.find("windows") != std::string::npos) {
300 TargetType = isWindows;
302 } else if (TT.empty()) {
303 #if defined(__CYGWIN__)
304 TargetType = isCygwin;
305 #elif defined(__MINGW32__) || defined(__MINGW64__)
306 TargetType = isMingw;
307 #elif defined(__APPLE__)
308 TargetType = isDarwin;
309 #if __APPLE_CC__ > 5400
310 DarwinVers = 9; // GCC 5400+ is Leopard.
312 DarwinVers = 8; // Minimum supported darwin is Tiger.
315 #elif defined(_WIN32) || defined(_WIN64)
316 TargetType = isWindows;
317 #elif defined(__linux__)
318 // Linux doesn't imply ELF, but we don't currently support anything else.
324 // If the asm syntax hasn't been overridden on the command line, use whatever
326 if (AsmFlavor == X86Subtarget::Unset) {
327 AsmFlavor = (TargetType == isWindows)
328 ? X86Subtarget::Intel : X86Subtarget::ATT;
331 // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
333 if (TargetType == isDarwin || Is64Bit)
337 stackAlignment = StackAlignment;