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 return (!isDirectCall &&
44 (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage() ||
45 GV->hasCommonLinkage() ||
46 (GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode())));
47 } else if (isTargetELF()) {
48 // Extra load is needed for all externally visible.
51 if (GV->hasInternalLinkage() || GV->hasHiddenVisibility())
54 } else if (isTargetCygMing() || isTargetWindows()) {
55 return (GV->hasDLLImportLinkage());
62 /// getBZeroEntry - This function returns the name of a function which has an
63 /// interface like the non-standard bzero function, if such a function exists on
64 /// the current subtarget and it is considered prefereable over memset with zero
65 /// passed as the second argument. Otherwise it returns null.
66 const char *X86Subtarget::getBZeroEntry() const {
67 // Darwin 10 has a __bzero entry point for this purpose.
68 if (getDarwinVers() >= 10)
74 /// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
75 /// specified arguments. If we can't run cpuid on the host, return true.
76 bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
77 unsigned *rECX, unsigned *rEDX) {
78 #if defined(__x86_64__)
79 // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
80 asm ("movq\t%%rbx, %%rsi\n\t"
82 "xchgq\t%%rbx, %%rsi\n\t"
89 #elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
91 asm ("movl\t%%ebx, %%esi\n\t"
93 "xchgl\t%%ebx, %%esi\n\t"
100 #elif defined(_MSC_VER)
105 mov dword ptr [esi],eax
107 mov dword ptr [esi],ebx
109 mov dword ptr [esi],ecx
111 mov dword ptr [esi],edx
119 void X86Subtarget::AutoDetectSubtargetFeatures() {
120 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
126 if (X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
129 X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
131 if ((EDX >> 23) & 0x1) X86SSELevel = MMX;
132 if ((EDX >> 25) & 0x1) X86SSELevel = SSE1;
133 if ((EDX >> 26) & 0x1) X86SSELevel = SSE2;
134 if (ECX & 0x1) X86SSELevel = SSE3;
135 if ((ECX >> 9) & 0x1) X86SSELevel = SSSE3;
136 if ((ECX >> 19) & 0x1) X86SSELevel = SSE41;
137 if ((ECX >> 20) & 0x1) X86SSELevel = SSE42;
139 if (memcmp(text.c, "GenuineIntel", 12) == 0 ||
140 memcmp(text.c, "AuthenticAMD", 12) == 0) {
141 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
142 HasX86_64 = (EDX >> 29) & 0x1;
146 static const char *GetCurrentX86CPU() {
147 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
148 if (X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
150 unsigned Family = (EAX >> 8) & 0xf; // Bits 8 - 11
151 unsigned Model = (EAX >> 4) & 0xf; // Bits 4 - 7
152 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
153 bool Em64T = (EDX >> 29) & 0x1;
160 X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1);
161 if (memcmp(text.c, "GenuineIntel", 12) == 0) {
169 case 4: return "pentium-mmx";
170 default: return "pentium";
174 case 1: return "pentiumpro";
177 case 6: return "pentium2";
181 case 11: return "pentium3";
183 case 13: return "pentium-m";
184 case 14: return "yonah";
185 case 15: return "core2";
186 default: return "i686";
192 return (Em64T) ? "nocona" : "prescott";
194 return (Em64T) ? "x86-64" : "pentium4";
201 } else if (memcmp(text.c, "AuthenticAMD", 12) == 0) {
202 // FIXME: this poorly matches the generated SubtargetFeatureKV table. There
203 // appears to be no way to generate the wide variety of AMD-specific targets
204 // from the information returned from CPUID.
212 case 8: return "k6-2";
214 case 13: return "k6-3";
215 default: return "pentium";
219 case 4: return "athlon-tbird";
222 case 8: return "athlon-mp";
223 case 10: return "athlon-xp";
224 default: return "athlon";
228 case 1: return "opteron";
229 case 5: return "athlon-fx"; // also opteron
230 default: return "athlon64";
240 X86Subtarget::X86Subtarget(const Module &M, const std::string &FS, bool is64Bit)
241 : AsmFlavor(AsmWriterFlavor)
242 , PICStyle(PICStyle::None)
243 , X86SSELevel(NoMMXSSE)
244 , X863DNowLevel(NoThreeDNow)
249 // FIXME: this is a known good value for Yonah. How about others?
250 , MaxInlineSizeThreshold(128)
252 , TargetType(isELF) { // Default to ELF unless otherwise specified.
254 // Determine default and user specified characteristics
256 // If feature string is not empty, parse features string.
257 std::string CPU = GetCurrentX86CPU();
258 ParseSubtargetFeatures(FS, CPU);
260 // Otherwise, use CPUID to auto-detect feature set.
261 AutoDetectSubtargetFeatures();
264 // If requesting codegen for X86-64, make sure that 64-bit and SSE2 features
265 // are enabled. These are available on all x86-64 CPUs.
268 if (X86SSELevel < SSE2)
272 // Set the boolean corresponding to the current target triple, or the default
273 // if one cannot be determined, to true.
274 const std::string& TT = M.getTargetTriple();
275 if (TT.length() > 5) {
277 if ((Pos = TT.find("-darwin")) != std::string::npos) {
278 TargetType = isDarwin;
280 // Compute the darwin version number.
281 if (isdigit(TT[Pos+7]))
282 DarwinVers = atoi(&TT[Pos+7]);
284 DarwinVers = 8; // Minimum supported darwin is Tiger.
285 } else if (TT.find("linux") != std::string::npos) {
286 // Linux doesn't imply ELF, but we don't currently support anything else.
289 } else if (TT.find("cygwin") != std::string::npos) {
290 TargetType = isCygwin;
291 } else if (TT.find("mingw") != std::string::npos) {
292 TargetType = isMingw;
293 } else if (TT.find("win32") != std::string::npos) {
294 TargetType = isWindows;
295 } else if (TT.find("windows") != std::string::npos) {
296 TargetType = isWindows;
298 } else if (TT.empty()) {
299 #if defined(__CYGWIN__)
300 TargetType = isCygwin;
301 #elif defined(__MINGW32__) || defined(__MINGW64__)
302 TargetType = isMingw;
303 #elif defined(__APPLE__)
304 TargetType = isDarwin;
305 #if __APPLE_CC__ > 5400
306 DarwinVers = 9; // GCC 5400+ is Leopard.
308 DarwinVers = 8; // Minimum supported darwin is Tiger.
311 #elif defined(_WIN32) || defined(_WIN64)
312 TargetType = isWindows;
313 #elif defined(__linux__)
314 // Linux doesn't imply ELF, but we don't currently support anything else.
320 // If the asm syntax hasn't been overridden on the command line, use whatever
322 if (AsmFlavor == X86Subtarget::Unset) {
323 AsmFlavor = (TargetType == isWindows)
324 ? X86Subtarget::Intel : X86Subtarget::ATT;
327 // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
329 if (TargetType == isDarwin || Is64Bit)
333 stackAlignment = StackAlignment;