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 if (isTargetDarwin()) {
42 return (!isDirectCall &&
43 (GV->hasWeakLinkage() || GV->hasLinkOnceLinkage() ||
44 GV->hasCommonLinkage() ||
45 (GV->isDeclaration() && !GV->hasNotBeenReadFromBitcode())));
46 } else if (isTargetELF()) {
47 // Extra load is needed for all externally visible.
50 if (GV->hasInternalLinkage() || GV->hasHiddenVisibility())
53 } else if (isTargetCygMing() || isTargetWindows()) {
54 return (GV->hasDLLImportLinkage());
61 /// This function returns the name of a function which has an interface
62 /// like the non-standard bzero function, if such a function exists on
63 /// the current subtarget and it is considered prefereable over
64 /// memset with zero passed as the second argument. Otherwise it
66 const char *X86Subtarget::getBZeroEntry() const {
68 // Darwin 10 has a __bzero entry point for this purpose.
69 if (getDarwinVers() >= 10)
75 /// GetCpuIDAndInfo - Execute the specified cpuid and return the 4 values in the
76 /// specified arguments. If we can't run cpuid on the host, return true.
77 bool X86::GetCpuIDAndInfo(unsigned value, unsigned *rEAX, unsigned *rEBX,
78 unsigned *rECX, unsigned *rEDX) {
79 #if defined(__x86_64__)
80 // gcc doesn't know cpuid would clobber ebx/rbx. Preseve it manually.
81 asm ("movq\t%%rbx, %%rsi\n\t"
83 "xchgq\t%%rbx, %%rsi\n\t"
90 #elif defined(i386) || defined(__i386__) || defined(__x86__) || defined(_M_IX86)
92 asm ("movl\t%%ebx, %%esi\n\t"
94 "xchgl\t%%ebx, %%esi\n\t"
101 #elif defined(_MSC_VER)
106 mov dword ptr [esi],eax
108 mov dword ptr [esi],ebx
110 mov dword ptr [esi],ecx
112 mov dword ptr [esi],edx
120 void X86Subtarget::AutoDetectSubtargetFeatures() {
121 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
127 if (X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1))
130 X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX);
132 if ((EDX >> 23) & 0x1) X86SSELevel = MMX;
133 if ((EDX >> 25) & 0x1) X86SSELevel = SSE1;
134 if ((EDX >> 26) & 0x1) X86SSELevel = SSE2;
135 if (ECX & 0x1) X86SSELevel = SSE3;
136 if ((ECX >> 9) & 0x1) X86SSELevel = SSSE3;
137 if ((ECX >> 19) & 0x1) X86SSELevel = SSE41;
138 if ((ECX >> 20) & 0x1) X86SSELevel = SSE42;
140 if (memcmp(text.c, "GenuineIntel", 12) == 0 ||
141 memcmp(text.c, "AuthenticAMD", 12) == 0) {
142 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
143 HasX86_64 = (EDX >> 29) & 0x1;
147 static const char *GetCurrentX86CPU() {
148 unsigned EAX = 0, EBX = 0, ECX = 0, EDX = 0;
149 if (X86::GetCpuIDAndInfo(0x1, &EAX, &EBX, &ECX, &EDX))
151 unsigned Family = (EAX >> 8) & 0xf; // Bits 8 - 11
152 unsigned Model = (EAX >> 4) & 0xf; // Bits 4 - 7
153 X86::GetCpuIDAndInfo(0x80000001, &EAX, &EBX, &ECX, &EDX);
154 bool Em64T = (EDX >> 29) & 0x1;
161 X86::GetCpuIDAndInfo(0, &EAX, text.u+0, text.u+2, text.u+1);
162 if (memcmp(text.c, "GenuineIntel", 12) == 0) {
170 case 4: return "pentium-mmx";
171 default: return "pentium";
175 case 1: return "pentiumpro";
178 case 6: return "pentium2";
182 case 11: return "pentium3";
184 case 13: return "pentium-m";
185 case 14: return "yonah";
186 case 15: return "core2";
187 default: return "i686";
193 return (Em64T) ? "nocona" : "prescott";
195 return (Em64T) ? "x86-64" : "pentium4";
202 } else if (memcmp(text.c, "AuthenticAMD", 12) == 0) {
203 // FIXME: this poorly matches the generated SubtargetFeatureKV table. There
204 // appears to be no way to generate the wide variety of AMD-specific targets
205 // from the information returned from CPUID.
213 case 8: return "k6-2";
215 case 13: return "k6-3";
216 default: return "pentium";
220 case 4: return "athlon-tbird";
223 case 8: return "athlon-mp";
224 case 10: return "athlon-xp";
225 default: return "athlon";
229 case 1: return "opteron";
230 case 5: return "athlon-fx"; // also opteron
231 default: return "athlon64";
241 X86Subtarget::X86Subtarget(const Module &M, const std::string &FS, bool is64Bit)
242 : AsmFlavor(AsmWriterFlavor)
243 , PICStyle(PICStyle::None)
244 , X86SSELevel(NoMMXSSE)
245 , X863DNowLevel(NoThreeDNow)
250 // FIXME: this is a known good value for Yonah. How about others?
251 , MaxInlineSizeThreshold(128)
253 , TargetType(isELF) { // Default to ELF unless otherwise specified.
255 // Determine default and user specified characteristics
257 // If feature string is not empty, parse features string.
258 std::string CPU = GetCurrentX86CPU();
259 ParseSubtargetFeatures(FS, CPU);
261 // Otherwise, use CPUID to auto-detect feature set.
262 AutoDetectSubtargetFeatures();
265 // If requesting codegen for X86-64, make sure that 64-bit and SSE2 features
266 // are enabled. These are available on all x86-64 CPUs.
269 if (X86SSELevel < SSE2)
273 // Set the boolean corresponding to the current target triple, or the default
274 // if one cannot be determined, to true.
275 const std::string& TT = M.getTargetTriple();
276 if (TT.length() > 5) {
278 if ((Pos = TT.find("-darwin")) != std::string::npos) {
279 TargetType = isDarwin;
281 // Compute the darwin version number.
282 if (isdigit(TT[Pos+7]))
283 DarwinVers = atoi(&TT[Pos+7]);
285 DarwinVers = 8; // Minimum supported darwin is Tiger.
286 } else if (TT.find("linux") != std::string::npos) {
287 // Linux doesn't imply ELF, but we don't currently support anything else.
290 } else if (TT.find("cygwin") != std::string::npos) {
291 TargetType = isCygwin;
292 } else if (TT.find("mingw") != std::string::npos) {
293 TargetType = isMingw;
294 } else if (TT.find("win32") != std::string::npos) {
295 TargetType = isWindows;
296 } else if (TT.find("windows") != std::string::npos) {
297 TargetType = isWindows;
299 } else if (TT.empty()) {
300 #if defined(__CYGWIN__)
301 TargetType = isCygwin;
302 #elif defined(__MINGW32__) || defined(__MINGW64__)
303 TargetType = isMingw;
304 #elif defined(__APPLE__)
305 TargetType = isDarwin;
306 #if __APPLE_CC__ > 5400
307 DarwinVers = 9; // GCC 5400+ is Leopard.
309 DarwinVers = 8; // Minimum supported darwin is Tiger.
312 #elif defined(_WIN32) || defined(_WIN64)
313 TargetType = isWindows;
314 #elif defined(__linux__)
315 // Linux doesn't imply ELF, but we don't currently support anything else.
321 // If the asm syntax hasn't been overridden on the command line, use whatever
323 if (AsmFlavor == X86Subtarget::Unset) {
324 AsmFlavor = (TargetType == isWindows)
325 ? X86Subtarget::Intel : X86Subtarget::ATT;
328 // Stack alignment is 16 bytes on Darwin (both 32 and 64 bit) and for all 64
330 if (TargetType == isDarwin || Is64Bit)
334 stackAlignment = StackAlignment;