lib/Target/X86/X86JITInfo.cpp

   1 //===-- X86JITInfo.cpp - Implement the JIT interfaces for the X86 target --===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the JIT interfaces for the X86 target.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "jit"
  15 #include "X86JITInfo.h"
  16 #include "X86Relocations.h"
  17 #include "X86Subtarget.h"
  18 #include "X86TargetMachine.h"
  19 #include "llvm/Function.h"
  20 #include "llvm/Support/Compiler.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/System/Valgrind.h"
  23 #include <cstdlib>
  24 #include <cstring>
  25 using namespace llvm;
  26
  27 // Determine the platform we're running on
  28 #if defined (__x86_64__) || defined (_M_AMD64) || defined (_M_X64)
  29 # define X86_64_JIT
  30 #elif defined(__i386__) || defined(i386) || defined(_M_IX86)
  31 # define X86_32_JIT
  32 #endif
  33
  34 void X86JITInfo::replaceMachineCodeForFunction(void *Old, void *New) {
  35   unsigned char *OldByte = (unsigned char *)Old;
  36   *OldByte++ = 0xE9;                // Emit JMP opcode.
  37   unsigned *OldWord = (unsigned *)OldByte;
  38   unsigned NewAddr = (intptr_t)New;
  39   unsigned OldAddr = (intptr_t)OldWord;
  40   *OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
  41
  42   // X86 doesn't need to invalidate the processor cache, so just invalidate
  43   // Valgrind's cache directly.
  44   sys::ValgrindDiscardTranslations(Old, 5);
  45 }
  46
  47
  48 /// JITCompilerFunction - This contains the address of the JIT function used to
  49 /// compile a function lazily.
  50 static TargetJITInfo::JITCompilerFn JITCompilerFunction;
  51
  52 // Get the ASMPREFIX for the current host.  This is often '_'.
  53 #ifndef __USER_LABEL_PREFIX__
  54 #define __USER_LABEL_PREFIX__
  55 #endif
  56 #define GETASMPREFIX2(X) #X
  57 #define GETASMPREFIX(X) GETASMPREFIX2(X)
  58 #define ASMPREFIX GETASMPREFIX(__USER_LABEL_PREFIX__)
  59
  60 // For ELF targets, use a .size and .type directive, to let tools
  61 // know the extent of functions defined in assembler.
  62 #if defined(__ELF__)
  63 # define SIZE(sym) ".size " #sym ", . - " #sym "\n"
  64 # define TYPE_FUNCTION(sym) ".type " #sym ", @function\n"
  65 #else
  66 # define SIZE(sym)
  67 # define TYPE_FUNCTION(sym)
  68 #endif
  69
  70 // Provide a convenient way for disabling usage of CFI directives.
  71 // This is needed for old/broken assemblers (for example, gas on
  72 // Darwin is pretty old and doesn't support these directives)
  73 #if defined(__APPLE__)
  74 # define CFI(x)
  75 #else
  76 // FIXME: Disable this until we really want to use it. Also, we will
  77 //        need to add some workarounds for compilers, which support
  78 //        only subset of these directives.
  79 # define CFI(x)
  80 #endif
  81
  82 // Provide a wrapper for X86CompilationCallback2 that saves non-traditional
  83 // callee saved registers, for the fastcc calling convention.
  84 extern "C" {
  85 #if defined(X86_64_JIT)
  86 # ifndef _MSC_VER
  87   // No need to save EAX/EDX for X86-64.
  88   void X86CompilationCallback(void);
  89   asm(
  90     ".text\n"
  91     ".align 8\n"
  92     ".globl " ASMPREFIX "X86CompilationCallback\n"
  93     TYPE_FUNCTION(X86CompilationCallback)
  94   ASMPREFIX "X86CompilationCallback:\n"
  95     CFI(".cfi_startproc\n")
  96     // Save RBP
  97     "pushq   %rbp\n"
  98     CFI(".cfi_def_cfa_offset 16\n")
  99     CFI(".cfi_offset %rbp, -16\n")
 100     // Save RSP
 101     "movq    %rsp, %rbp\n"
 102     CFI(".cfi_def_cfa_register %rbp\n")
 103     // Save all int arg registers
 104     "pushq   %rdi\n"
 105     CFI(".cfi_rel_offset %rdi, 0\n")
 106     "pushq   %rsi\n"
 107     CFI(".cfi_rel_offset %rsi, 8\n")
 108     "pushq   %rdx\n"
 109     CFI(".cfi_rel_offset %rdx, 16\n")
 110     "pushq   %rcx\n"
 111     CFI(".cfi_rel_offset %rcx, 24\n")
 112     "pushq   %r8\n"
 113     CFI(".cfi_rel_offset %r8, 32\n")
 114     "pushq   %r9\n"
 115     CFI(".cfi_rel_offset %r9, 40\n")
 116     // Align stack on 16-byte boundary. ESP might not be properly aligned
 117     // (8 byte) if this is called from an indirect stub.
 118     "andq    $-16, %rsp\n"
 119     // Save all XMM arg registers
 120     "subq    $128, %rsp\n"
 121     "movaps  %xmm0, (%rsp)\n"
 122     "movaps  %xmm1, 16(%rsp)\n"
 123     "movaps  %xmm2, 32(%rsp)\n"
 124     "movaps  %xmm3, 48(%rsp)\n"
 125     "movaps  %xmm4, 64(%rsp)\n"
 126     "movaps  %xmm5, 80(%rsp)\n"
 127     "movaps  %xmm6, 96(%rsp)\n"
 128     "movaps  %xmm7, 112(%rsp)\n"
 129     // JIT callee
 130     "movq    %rbp, %rdi\n"    // Pass prev frame and return address
 131     "movq    8(%rbp), %rsi\n"
 132     "call    " ASMPREFIX "X86CompilationCallback2\n"
 133     // Restore all XMM arg registers
 134     "movaps  112(%rsp), %xmm7\n"
 135     "movaps  96(%rsp), %xmm6\n"
 136     "movaps  80(%rsp), %xmm5\n"
 137     "movaps  64(%rsp), %xmm4\n"
 138     "movaps  48(%rsp), %xmm3\n"
 139     "movaps  32(%rsp), %xmm2\n"
 140     "movaps  16(%rsp), %xmm1\n"
 141     "movaps  (%rsp), %xmm0\n"
 142     // Restore RSP
 143     "movq    %rbp, %rsp\n"
 144     CFI(".cfi_def_cfa_register %rsp\n")
 145     // Restore all int arg registers
 146     "subq    $48, %rsp\n"
 147     CFI(".cfi_adjust_cfa_offset 48\n")
 148     "popq    %r9\n"
 149     CFI(".cfi_adjust_cfa_offset -8\n")
 150     CFI(".cfi_restore %r9\n")
 151     "popq    %r8\n"
 152     CFI(".cfi_adjust_cfa_offset -8\n")
 153     CFI(".cfi_restore %r8\n")
 154     "popq    %rcx\n"
 155     CFI(".cfi_adjust_cfa_offset -8\n")
 156     CFI(".cfi_restore %rcx\n")
 157     "popq    %rdx\n"
 158     CFI(".cfi_adjust_cfa_offset -8\n")
 159     CFI(".cfi_restore %rdx\n")
 160     "popq    %rsi\n"
 161     CFI(".cfi_adjust_cfa_offset -8\n")
 162     CFI(".cfi_restore %rsi\n")
 163     "popq    %rdi\n"
 164     CFI(".cfi_adjust_cfa_offset -8\n")
 165     CFI(".cfi_restore %rdi\n")
 166     // Restore RBP
 167     "popq    %rbp\n"
 168     CFI(".cfi_adjust_cfa_offset -8\n")
 169     CFI(".cfi_restore %rbp\n")
 170     "ret\n"
 171     CFI(".cfi_endproc\n")
 172     SIZE(X86CompilationCallback)
 173   );
 174 # else
 175   // No inline assembler support on this platform. The routine is in external
 176   // file.
 177   void X86CompilationCallback();
 178
 179 # endif
 180 #elif defined (X86_32_JIT)
 181 # ifndef _MSC_VER
 182   void X86CompilationCallback(void);
 183   asm(
 184     ".text\n"
 185     ".align 8\n"
 186     ".globl " ASMPREFIX "X86CompilationCallback\n"
 187     TYPE_FUNCTION(X86CompilationCallback)
 188   ASMPREFIX "X86CompilationCallback:\n"
 189     CFI(".cfi_startproc\n")
 190     "pushl   %ebp\n"
 191     CFI(".cfi_def_cfa_offset 8\n")
 192     CFI(".cfi_offset %ebp, -8\n")
 193     "movl    %esp, %ebp\n"    // Standard prologue
 194     CFI(".cfi_def_cfa_register %ebp\n")
 195     "pushl   %eax\n"
 196     CFI(".cfi_rel_offset %eax, 0\n")
 197     "pushl   %edx\n"          // Save EAX/EDX/ECX
 198     CFI(".cfi_rel_offset %edx, 4\n")
 199     "pushl   %ecx\n"
 200     CFI(".cfi_rel_offset %ecx, 8\n")
 201 #  if defined(__APPLE__)
 202     "andl    $-16, %esp\n"    // Align ESP on 16-byte boundary
 203 #  endif
 204     "subl    $16, %esp\n"
 205     "movl    4(%ebp), %eax\n" // Pass prev frame and return address
 206     "movl    %eax, 4(%esp)\n"
 207     "movl    %ebp, (%esp)\n"
 208     "call    " ASMPREFIX "X86CompilationCallback2\n"
 209     "movl    %ebp, %esp\n"    // Restore ESP
 210     CFI(".cfi_def_cfa_register %esp\n")
 211     "subl    $12, %esp\n"
 212     CFI(".cfi_adjust_cfa_offset 12\n")
 213     "popl    %ecx\n"
 214     CFI(".cfi_adjust_cfa_offset -4\n")
 215     CFI(".cfi_restore %ecx\n")
 216     "popl    %edx\n"
 217     CFI(".cfi_adjust_cfa_offset -4\n")
 218     CFI(".cfi_restore %edx\n")
 219     "popl    %eax\n"
 220     CFI(".cfi_adjust_cfa_offset -4\n")
 221     CFI(".cfi_restore %eax\n")
 222     "popl    %ebp\n"
 223     CFI(".cfi_adjust_cfa_offset -4\n")
 224     CFI(".cfi_restore %ebp\n")
 225     "ret\n"
 226     CFI(".cfi_endproc\n")
 227     SIZE(X86CompilationCallback)
 228   );
 229
 230   // Same as X86CompilationCallback but also saves XMM argument registers.
 231   void X86CompilationCallback_SSE(void);
 232   asm(
 233     ".text\n"
 234     ".align 8\n"
 235     ".globl " ASMPREFIX "X86CompilationCallback_SSE\n"
 236     TYPE_FUNCTION(X86CompilationCallback_SSE)
 237   ASMPREFIX "X86CompilationCallback_SSE:\n"
 238     CFI(".cfi_startproc\n")
 239     "pushl   %ebp\n"
 240     CFI(".cfi_def_cfa_offset 8\n")
 241     CFI(".cfi_offset %ebp, -8\n")
 242     "movl    %esp, %ebp\n"    // Standard prologue
 243     CFI(".cfi_def_cfa_register %ebp\n")
 244     "pushl   %eax\n"
 245     CFI(".cfi_rel_offset %eax, 0\n")
 246     "pushl   %edx\n"          // Save EAX/EDX/ECX
 247     CFI(".cfi_rel_offset %edx, 4\n")
 248     "pushl   %ecx\n"
 249     CFI(".cfi_rel_offset %ecx, 8\n")
 250     "andl    $-16, %esp\n"    // Align ESP on 16-byte boundary
 251     // Save all XMM arg registers
 252     "subl    $64, %esp\n"
 253     // FIXME: provide frame move information for xmm registers.
 254     // This can be tricky, because CFA register is ebp (unaligned)
 255     // and we need to produce offsets relative to it.
 256     "movaps  %xmm0, (%esp)\n"
 257     "movaps  %xmm1, 16(%esp)\n"
 258     "movaps  %xmm2, 32(%esp)\n"
 259     "movaps  %xmm3, 48(%esp)\n"
 260     "subl    $16, %esp\n"
 261     "movl    4(%ebp), %eax\n" // Pass prev frame and return address
 262     "movl    %eax, 4(%esp)\n"
 263     "movl    %ebp, (%esp)\n"
 264     "call    " ASMPREFIX "X86CompilationCallback2\n"
 265     "addl    $16, %esp\n"
 266     "movaps  48(%esp), %xmm3\n"
 267     CFI(".cfi_restore %xmm3\n")
 268     "movaps  32(%esp), %xmm2\n"
 269     CFI(".cfi_restore %xmm2\n")
 270     "movaps  16(%esp), %xmm1\n"
 271     CFI(".cfi_restore %xmm1\n")
 272     "movaps  (%esp), %xmm0\n"
 273     CFI(".cfi_restore %xmm0\n")
 274     "movl    %ebp, %esp\n"    // Restore ESP
 275     CFI(".cfi_def_cfa_register esp\n")
 276     "subl    $12, %esp\n"
 277     CFI(".cfi_adjust_cfa_offset 12\n")
 278     "popl    %ecx\n"
 279     CFI(".cfi_adjust_cfa_offset -4\n")
 280     CFI(".cfi_restore %ecx\n")
 281     "popl    %edx\n"
 282     CFI(".cfi_adjust_cfa_offset -4\n")
 283     CFI(".cfi_restore %edx\n")
 284     "popl    %eax\n"
 285     CFI(".cfi_adjust_cfa_offset -4\n")
 286     CFI(".cfi_restore %eax\n")
 287     "popl    %ebp\n"
 288     CFI(".cfi_adjust_cfa_offset -4\n")
 289     CFI(".cfi_restore %ebp\n")
 290     "ret\n"
 291     CFI(".cfi_endproc\n")
 292     SIZE(X86CompilationCallback_SSE)
 293   );
 294 # else
 295   void X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr);
 296
 297   _declspec(naked) void X86CompilationCallback(void) {
 298     __asm {
 299       push  ebp
 300       mov   ebp, esp
 301       push  eax
 302       push  edx
 303       push  ecx
 304       and   esp, -16
 305       sub   esp, 16
 306       mov   eax, dword ptr [ebp+4]
 307       mov   dword ptr [esp+4], eax
 308       mov   dword ptr [esp], ebp
 309       call  X86CompilationCallback2
 310       mov   esp, ebp
 311       sub   esp, 12
 312       pop   ecx
 313       pop   edx
 314       pop   eax
 315       pop   ebp
 316       ret
 317     }
 318   }
 319
 320 # endif // _MSC_VER
 321
 322 #else // Not an i386 host
 323   void X86CompilationCallback() {
 324     llvm_unreachable("Cannot call X86CompilationCallback() on a non-x86 arch!");
 325   }
 326 #endif
 327 }
 328
 329 /// X86CompilationCallback2 - This is the target-specific function invoked by the
 330 /// function stub when we did not know the real target of a call.  This function
 331 /// must locate the start of the stub or call site and pass it into the JIT
 332 /// compiler function.
 333 extern "C" {
 334 #if !(defined (X86_64_JIT) && defined(_MSC_VER))
 335  // the following function is called only from this translation unit,
 336  // unless we are under 64bit Windows with MSC, where there is
 337  // no support for inline assembly
 338 static
 339 #endif
 340 void LLVM_ATTRIBUTE_USED
 341 X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
 342   intptr_t *RetAddrLoc = &StackPtr[1];
 343   assert(*RetAddrLoc == RetAddr &&
 344          "Could not find return address on the stack!");
 345
 346   // It's a stub if there is an interrupt marker after the call.
 347   bool isStub = ((unsigned char*)RetAddr)[0] == 0xCE;
 348
 349   // The call instruction should have pushed the return value onto the stack...
 350 #if defined (X86_64_JIT)
 351   RetAddr--;     // Backtrack to the reference itself...
 352 #else
 353   RetAddr -= 4;  // Backtrack to the reference itself...
 354 #endif
 355
 356 #if 0
 357   DEBUG(dbgs() << "In callback! Addr=" << (void*)RetAddr
 358                << " ESP=" << (void*)StackPtr
 359                << ": Resolving call to function: "
 360                << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
 361 #endif
 362
 363   // Sanity check to make sure this really is a call instruction.
 364 #if defined (X86_64_JIT)
 365   assert(((unsigned char*)RetAddr)[-2] == 0x41 &&"Not a call instr!");
 366   assert(((unsigned char*)RetAddr)[-1] == 0xFF &&"Not a call instr!");
 367 #else
 368   assert(((unsigned char*)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
 369 #endif
 370
 371   intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)RetAddr);
 372
 373   // Rewrite the call target... so that we don't end up here every time we
 374   // execute the call.
 375 #if defined (X86_64_JIT)
 376   assert(isStub &&
 377          "X86-64 doesn't support rewriting non-stub lazy compilation calls:"
 378          " the call instruction varies too much.");
 379 #else
 380   *(intptr_t *)RetAddr = (intptr_t)(NewVal-RetAddr-4);
 381 #endif
 382
 383   if (isStub) {
 384     // If this is a stub, rewrite the call into an unconditional branch
 385     // instruction so that two return addresses are not pushed onto the stack
 386     // when the requested function finally gets called.  This also makes the
 387     // 0xCE byte (interrupt) dead, so the marker doesn't effect anything.
 388 #if defined (X86_64_JIT)
 389     // If the target address is within 32-bit range of the stub, use a
 390     // PC-relative branch instead of loading the actual address.  (This is
 391     // considerably shorter than the 64-bit immediate load already there.)
 392     // We assume here intptr_t is 64 bits.
 393     intptr_t diff = NewVal-RetAddr+7;
 394     if (diff >= -2147483648LL && diff <= 2147483647LL) {
 395       *(unsigned char*)(RetAddr-0xc) = 0xE9;
 396       *(intptr_t *)(RetAddr-0xb) = diff & 0xffffffff;
 397     } else {
 398       *(intptr_t *)(RetAddr - 0xa) = NewVal;
 399       ((unsigned char*)RetAddr)[0] = (2 | (4 << 3) | (3 << 6));
 400     }
 401     sys::ValgrindDiscardTranslations((void*)(RetAddr-0xc), 0xd);
 402 #else
 403     ((unsigned char*)RetAddr)[-1] = 0xE9;
 404     sys::ValgrindDiscardTranslations((void*)(RetAddr-1), 5);
 405 #endif
 406   }
 407
 408   // Change the return address to reexecute the call instruction...
 409 #if defined (X86_64_JIT)
 410   *RetAddrLoc -= 0xd;
 411 #else
 412   *RetAddrLoc -= 5;
 413 #endif
 414 }
 415 }
 416
 417 TargetJITInfo::LazyResolverFn
 418 X86JITInfo::getLazyResolverFunction(JITCompilerFn F) {
 419   JITCompilerFunction = F;
 420
 421 #if defined (X86_32_JIT) && !defined (_MSC_VER)
 422   if (Subtarget->hasSSE1())
 423     return X86CompilationCallback_SSE;
 424 #endif
 425
 426   return X86CompilationCallback;
 427 }
 428
 429 X86JITInfo::X86JITInfo(X86TargetMachine &tm) : TM(tm) {
 430   Subtarget = &TM.getSubtarget<X86Subtarget>();
 431   useGOT = 0;
 432   TLSOffset = 0;
 433 }
 434
 435 void *X86JITInfo::emitGlobalValueIndirectSym(const GlobalValue* GV, void *ptr,
 436                                              JITCodeEmitter &JCE) {
 437 #if defined (X86_64_JIT)
 438   const unsigned Alignment = 8;
 439   uint8_t Buffer[8];
 440   uint8_t *Cur = Buffer;
 441   MachineCodeEmitter::emitWordLEInto(Cur, (unsigned)(intptr_t)ptr);
 442   MachineCodeEmitter::emitWordLEInto(Cur, (unsigned)(((intptr_t)ptr) >> 32));
 443 #else
 444   const unsigned Alignment = 4;
 445   uint8_t Buffer[4];
 446   uint8_t *Cur = Buffer;
 447   MachineCodeEmitter::emitWordLEInto(Cur, (intptr_t)ptr);
 448 #endif
 449   return JCE.allocIndirectGV(GV, Buffer, sizeof(Buffer), Alignment);
 450 }
 451
 452 TargetJITInfo::StubLayout X86JITInfo::getStubLayout() {
 453   // The 64-bit stub contains:
 454   //   movabs r10 <- 8-byte-target-address  # 10 bytes
 455   //   call|jmp *r10  # 3 bytes
 456   // The 32-bit stub contains a 5-byte call|jmp.
 457   // If the stub is a call to the compilation callback, an extra byte is added
 458   // to mark it as a stub.
 459   StubLayout Result = {14, 4};
 460   return Result;
 461 }
 462
 463 void *X86JITInfo::emitFunctionStub(const Function* F, void *Target,
 464                                    JITCodeEmitter &JCE) {
 465   // Note, we cast to intptr_t here to silence a -pedantic warning that
 466   // complains about casting a function pointer to a normal pointer.
 467 #if defined (X86_32_JIT) && !defined (_MSC_VER)
 468   bool NotCC = (Target != (void*)(intptr_t)X86CompilationCallback &&
 469                 Target != (void*)(intptr_t)X86CompilationCallback_SSE);
 470 #else
 471   bool NotCC = Target != (void*)(intptr_t)X86CompilationCallback;
 472 #endif
 473   JCE.emitAlignment(4);
 474   void *Result = (void*)JCE.getCurrentPCValue();
 475   if (NotCC) {
 476 #if defined (X86_64_JIT)
 477     JCE.emitByte(0x49);          // REX prefix
 478     JCE.emitByte(0xB8+2);        // movabsq r10
 479     JCE.emitWordLE((unsigned)(intptr_t)Target);
 480     JCE.emitWordLE((unsigned)(((intptr_t)Target) >> 32));
 481     JCE.emitByte(0x41);          // REX prefix
 482     JCE.emitByte(0xFF);          // jmpq *r10
 483     JCE.emitByte(2 | (4 << 3) | (3 << 6));
 484 #else
 485     JCE.emitByte(0xE9);
 486     JCE.emitWordLE((intptr_t)Target-JCE.getCurrentPCValue()-4);
 487 #endif
 488     return Result;
 489   }
 490
 491 #if defined (X86_64_JIT)
 492   JCE.emitByte(0x49);          // REX prefix
 493   JCE.emitByte(0xB8+2);        // movabsq r10
 494   JCE.emitWordLE((unsigned)(intptr_t)Target);
 495   JCE.emitWordLE((unsigned)(((intptr_t)Target) >> 32));
 496   JCE.emitByte(0x41);          // REX prefix
 497   JCE.emitByte(0xFF);          // callq *r10
 498   JCE.emitByte(2 | (2 << 3) | (3 << 6));
 499 #else
 500   JCE.emitByte(0xE8);   // Call with 32 bit pc-rel destination...
 501
 502   JCE.emitWordLE((intptr_t)Target-JCE.getCurrentPCValue()-4);
 503 #endif
 504
 505   // This used to use 0xCD, but that value is used by JITMemoryManager to
 506   // initialize the buffer with garbage, which means it may follow a
 507   // noreturn function call, confusing X86CompilationCallback2.  PR 4929.
 508   JCE.emitByte(0xCE);   // Interrupt - Just a marker identifying the stub!
 509   return Result;
 510 }
 511
 512 /// getPICJumpTableEntry - Returns the value of the jumptable entry for the
 513 /// specific basic block.
 514 uintptr_t X86JITInfo::getPICJumpTableEntry(uintptr_t BB, uintptr_t Entry) {
 515 #if defined(X86_64_JIT)
 516   return BB - Entry;
 517 #else
 518   return BB - PICBase;
 519 #endif
 520 }
 521
 522 /// relocate - Before the JIT can run a block of code that has been emitted,
 523 /// it must rewrite the code to contain the actual addresses of any
 524 /// referenced global symbols.
 525 void X86JITInfo::relocate(void *Function, MachineRelocation *MR,
 526                           unsigned NumRelocs, unsigned char* GOTBase) {
 527   for (unsigned i = 0; i != NumRelocs; ++i, ++MR) {
 528     void *RelocPos = (char*)Function + MR->getMachineCodeOffset();
 529     intptr_t ResultPtr = (intptr_t)MR->getResultPointer();
 530     switch ((X86::RelocationType)MR->getRelocationType()) {
 531     case X86::reloc_pcrel_word: {
 532       // PC relative relocation, add the relocated value to the value already in
 533       // memory, after we adjust it for where the PC is.
 534       ResultPtr = ResultPtr -(intptr_t)RelocPos - 4 - MR->getConstantVal();
 535       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 536       break;
 537     }
 538     case X86::reloc_picrel_word: {
 539       // PIC base relative relocation, add the relocated value to the value
 540       // already in memory, after we adjust it for where the PIC base is.
 541       ResultPtr = ResultPtr - ((intptr_t)Function + MR->getConstantVal());
 542       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 543       break;
 544     }
 545     case X86::reloc_absolute_word:
 546     case X86::reloc_absolute_word_sext:
 547       // Absolute relocation, just add the relocated value to the value already
 548       // in memory.
 549       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 550       break;
 551     case X86::reloc_absolute_dword:
 552       *((intptr_t*)RelocPos) += ResultPtr;
 553       break;
 554     }
 555   }
 556 }
 557
 558 char* X86JITInfo::allocateThreadLocalMemory(size_t size) {
 559 #if defined(X86_32_JIT) && !defined(__APPLE__) && !defined(_MSC_VER)
 560   TLSOffset -= size;
 561   return TLSOffset;
 562 #else
 563   llvm_unreachable("Cannot allocate thread local storage on this arch!");
 564   return 0;
 565 #endif
 566 }