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 <cstdlib>
  23 #include <cstring>
  24 using namespace llvm;
  25
  26 // Determine the platform we're running on
  27 #if defined (__x86_64__) || defined (_M_AMD64) || defined (_M_X64)
  28 # define X86_64_JIT
  29 #elif defined(__i386__) || defined(i386) || defined(_M_IX86)
  30 # define X86_32_JIT
  31 #endif
  32
  33 void X86JITInfo::replaceMachineCodeForFunction(void *Old, void *New) {
  34   unsigned char *OldByte = (unsigned char *)Old;
  35   *OldByte++ = 0xE9;                // Emit JMP opcode.
  36   unsigned *OldWord = (unsigned *)OldByte;
  37   unsigned NewAddr = (intptr_t)New;
  38   unsigned OldAddr = (intptr_t)OldWord;
  39   *OldWord = NewAddr - OldAddr - 4; // Emit PC-relative addr of New code.
  40 }
  41
  42
  43 /// JITCompilerFunction - This contains the address of the JIT function used to
  44 /// compile a function lazily.
  45 static TargetJITInfo::JITCompilerFn JITCompilerFunction;
  46
  47 // Get the ASMPREFIX for the current host.  This is often '_'.
  48 #ifndef __USER_LABEL_PREFIX__
  49 #define __USER_LABEL_PREFIX__
  50 #endif
  51 #define GETASMPREFIX2(X) #X
  52 #define GETASMPREFIX(X) GETASMPREFIX2(X)
  53 #define ASMPREFIX GETASMPREFIX(__USER_LABEL_PREFIX__)
  54
  55 // For ELF targets, use a .size and .type directive, to let tools
  56 // know the extent of functions defined in assembler.
  57 #if defined(__ELF__)
  58 # define SIZE(sym) ".size " #sym ", . - " #sym "\n"
  59 # define TYPE_FUNCTION(sym) ".type " #sym ", @function\n"
  60 #else
  61 # define SIZE(sym)
  62 # define TYPE_FUNCTION(sym)
  63 #endif
  64
  65 // Provide a convenient way for disabling usage of CFI directives.
  66 // This is needed for old/broken assemblers (for example, gas on
  67 // Darwin is pretty old and doesn't support these directives)
  68 #if defined(__APPLE__)
  69 # define CFI(x)
  70 #else
  71 // FIXME: Disable this until we really want to use it. Also, we will
  72 //        need to add some workarounds for compilers, which support
  73 //        only subset of these directives.
  74 # define CFI(x)
  75 #endif
  76
  77 // Provide a wrapper for X86CompilationCallback2 that saves non-traditional
  78 // callee saved registers, for the fastcc calling convention.
  79 extern "C" {
  80 #if defined(X86_64_JIT)
  81 # ifndef _MSC_VER
  82   // No need to save EAX/EDX for X86-64.
  83   void X86CompilationCallback(void);
  84   asm(
  85     ".text\n"
  86     ".align 8\n"
  87     ".globl " ASMPREFIX "X86CompilationCallback\n"
  88     TYPE_FUNCTION(X86CompilationCallback)
  89   ASMPREFIX "X86CompilationCallback:\n"
  90     CFI(".cfi_startproc\n")
  91     // Save RBP
  92     "pushq   %rbp\n"
  93     CFI(".cfi_def_cfa_offset 16\n")
  94     CFI(".cfi_offset %rbp, -16\n")
  95     // Save RSP
  96     "movq    %rsp, %rbp\n"
  97     CFI(".cfi_def_cfa_register %rbp\n")
  98     // Save all int arg registers
  99     "pushq   %rdi\n"
 100     CFI(".cfi_rel_offset %rdi, 0\n")
 101     "pushq   %rsi\n"
 102     CFI(".cfi_rel_offset %rsi, 8\n")
 103     "pushq   %rdx\n"
 104     CFI(".cfi_rel_offset %rdx, 16\n")
 105     "pushq   %rcx\n"
 106     CFI(".cfi_rel_offset %rcx, 24\n")
 107     "pushq   %r8\n"
 108     CFI(".cfi_rel_offset %r8, 32\n")
 109     "pushq   %r9\n"
 110     CFI(".cfi_rel_offset %r9, 40\n")
 111     // Align stack on 16-byte boundary. ESP might not be properly aligned
 112     // (8 byte) if this is called from an indirect stub.
 113     "andq    $-16, %rsp\n"
 114     // Save all XMM arg registers
 115     "subq    $128, %rsp\n"
 116     "movaps  %xmm0, (%rsp)\n"
 117     "movaps  %xmm1, 16(%rsp)\n"
 118     "movaps  %xmm2, 32(%rsp)\n"
 119     "movaps  %xmm3, 48(%rsp)\n"
 120     "movaps  %xmm4, 64(%rsp)\n"
 121     "movaps  %xmm5, 80(%rsp)\n"
 122     "movaps  %xmm6, 96(%rsp)\n"
 123     "movaps  %xmm7, 112(%rsp)\n"
 124     // JIT callee
 125     "movq    %rbp, %rdi\n"    // Pass prev frame and return address
 126     "movq    8(%rbp), %rsi\n"
 127     "call    " ASMPREFIX "X86CompilationCallback2\n"
 128     // Restore all XMM arg registers
 129     "movaps  112(%rsp), %xmm7\n"
 130     "movaps  96(%rsp), %xmm6\n"
 131     "movaps  80(%rsp), %xmm5\n"
 132     "movaps  64(%rsp), %xmm4\n"
 133     "movaps  48(%rsp), %xmm3\n"
 134     "movaps  32(%rsp), %xmm2\n"
 135     "movaps  16(%rsp), %xmm1\n"
 136     "movaps  (%rsp), %xmm0\n"
 137     // Restore RSP
 138     "movq    %rbp, %rsp\n"
 139     CFI(".cfi_def_cfa_register %rsp\n")
 140     // Restore all int arg registers
 141     "subq    $48, %rsp\n"
 142     CFI(".cfi_adjust_cfa_offset 48\n")
 143     "popq    %r9\n"
 144     CFI(".cfi_adjust_cfa_offset -8\n")
 145     CFI(".cfi_restore %r9\n")
 146     "popq    %r8\n"
 147     CFI(".cfi_adjust_cfa_offset -8\n")
 148     CFI(".cfi_restore %r8\n")
 149     "popq    %rcx\n"
 150     CFI(".cfi_adjust_cfa_offset -8\n")
 151     CFI(".cfi_restore %rcx\n")
 152     "popq    %rdx\n"
 153     CFI(".cfi_adjust_cfa_offset -8\n")
 154     CFI(".cfi_restore %rdx\n")
 155     "popq    %rsi\n"
 156     CFI(".cfi_adjust_cfa_offset -8\n")
 157     CFI(".cfi_restore %rsi\n")
 158     "popq    %rdi\n"
 159     CFI(".cfi_adjust_cfa_offset -8\n")
 160     CFI(".cfi_restore %rdi\n")
 161     // Restore RBP
 162     "popq    %rbp\n"
 163     CFI(".cfi_adjust_cfa_offset -8\n")
 164     CFI(".cfi_restore %rbp\n")
 165     "ret\n"
 166     CFI(".cfi_endproc\n")
 167     SIZE(X86CompilationCallback)
 168   );
 169 # else
 170   // No inline assembler support on this platform. The routine is in external
 171   // file.
 172   void X86CompilationCallback();
 173
 174 # endif
 175 #elif defined (X86_32_JIT)
 176 # ifndef _MSC_VER
 177   void X86CompilationCallback(void);
 178   asm(
 179     ".text\n"
 180     ".align 8\n"
 181     ".globl " ASMPREFIX "X86CompilationCallback\n"
 182     TYPE_FUNCTION(X86CompilationCallback)
 183   ASMPREFIX "X86CompilationCallback:\n"
 184     CFI(".cfi_startproc\n")
 185     "pushl   %ebp\n"
 186     CFI(".cfi_def_cfa_offset 8\n")
 187     CFI(".cfi_offset %ebp, -8\n")
 188     "movl    %esp, %ebp\n"    // Standard prologue
 189     CFI(".cfi_def_cfa_register %ebp\n")
 190     "pushl   %eax\n"
 191     CFI(".cfi_rel_offset %eax, 0\n")
 192     "pushl   %edx\n"          // Save EAX/EDX/ECX
 193     CFI(".cfi_rel_offset %edx, 4\n")
 194     "pushl   %ecx\n"
 195     CFI(".cfi_rel_offset %ecx, 8\n")
 196 #  if defined(__APPLE__)
 197     "andl    $-16, %esp\n"    // Align ESP on 16-byte boundary
 198 #  endif
 199     "subl    $16, %esp\n"
 200     "movl    4(%ebp), %eax\n" // Pass prev frame and return address
 201     "movl    %eax, 4(%esp)\n"
 202     "movl    %ebp, (%esp)\n"
 203     "call    " ASMPREFIX "X86CompilationCallback2\n"
 204     "movl    %ebp, %esp\n"    // Restore ESP
 205     CFI(".cfi_def_cfa_register %esp\n")
 206     "subl    $12, %esp\n"
 207     CFI(".cfi_adjust_cfa_offset 12\n")
 208     "popl    %ecx\n"
 209     CFI(".cfi_adjust_cfa_offset -4\n")
 210     CFI(".cfi_restore %ecx\n")
 211     "popl    %edx\n"
 212     CFI(".cfi_adjust_cfa_offset -4\n")
 213     CFI(".cfi_restore %edx\n")
 214     "popl    %eax\n"
 215     CFI(".cfi_adjust_cfa_offset -4\n")
 216     CFI(".cfi_restore %eax\n")
 217     "popl    %ebp\n"
 218     CFI(".cfi_adjust_cfa_offset -4\n")
 219     CFI(".cfi_restore %ebp\n")
 220     "ret\n"
 221     CFI(".cfi_endproc\n")
 222     SIZE(X86CompilationCallback)
 223   );
 224
 225   // Same as X86CompilationCallback but also saves XMM argument registers.
 226   void X86CompilationCallback_SSE(void);
 227   asm(
 228     ".text\n"
 229     ".align 8\n"
 230     ".globl " ASMPREFIX "X86CompilationCallback_SSE\n"
 231     TYPE_FUNCTION(X86CompilationCallback_SSE)
 232   ASMPREFIX "X86CompilationCallback_SSE:\n"
 233     CFI(".cfi_startproc\n")
 234     "pushl   %ebp\n"
 235     CFI(".cfi_def_cfa_offset 8\n")
 236     CFI(".cfi_offset %ebp, -8\n")
 237     "movl    %esp, %ebp\n"    // Standard prologue
 238     CFI(".cfi_def_cfa_register %ebp\n")
 239     "pushl   %eax\n"
 240     CFI(".cfi_rel_offset %eax, 0\n")
 241     "pushl   %edx\n"          // Save EAX/EDX/ECX
 242     CFI(".cfi_rel_offset %edx, 4\n")
 243     "pushl   %ecx\n"
 244     CFI(".cfi_rel_offset %ecx, 8\n")
 245     "andl    $-16, %esp\n"    // Align ESP on 16-byte boundary
 246     // Save all XMM arg registers
 247     "subl    $64, %esp\n"
 248     // FIXME: provide frame move information for xmm registers.
 249     // This can be tricky, because CFA register is ebp (unaligned)
 250     // and we need to produce offsets relative to it.
 251     "movaps  %xmm0, (%esp)\n"
 252     "movaps  %xmm1, 16(%esp)\n"
 253     "movaps  %xmm2, 32(%esp)\n"
 254     "movaps  %xmm3, 48(%esp)\n"
 255     "subl    $16, %esp\n"
 256     "movl    4(%ebp), %eax\n" // Pass prev frame and return address
 257     "movl    %eax, 4(%esp)\n"
 258     "movl    %ebp, (%esp)\n"
 259     "call    " ASMPREFIX "X86CompilationCallback2\n"
 260     "addl    $16, %esp\n"
 261     "movaps  48(%esp), %xmm3\n"
 262     CFI(".cfi_restore %xmm3\n")
 263     "movaps  32(%esp), %xmm2\n"
 264     CFI(".cfi_restore %xmm2\n")
 265     "movaps  16(%esp), %xmm1\n"
 266     CFI(".cfi_restore %xmm1\n")
 267     "movaps  (%esp), %xmm0\n"
 268     CFI(".cfi_restore %xmm0\n")
 269     "movl    %ebp, %esp\n"    // Restore ESP
 270     CFI(".cfi_def_cfa_register esp\n")
 271     "subl    $12, %esp\n"
 272     CFI(".cfi_adjust_cfa_offset 12\n")
 273     "popl    %ecx\n"
 274     CFI(".cfi_adjust_cfa_offset -4\n")
 275     CFI(".cfi_restore %ecx\n")
 276     "popl    %edx\n"
 277     CFI(".cfi_adjust_cfa_offset -4\n")
 278     CFI(".cfi_restore %edx\n")
 279     "popl    %eax\n"
 280     CFI(".cfi_adjust_cfa_offset -4\n")
 281     CFI(".cfi_restore %eax\n")
 282     "popl    %ebp\n"
 283     CFI(".cfi_adjust_cfa_offset -4\n")
 284     CFI(".cfi_restore %ebp\n")
 285     "ret\n"
 286     CFI(".cfi_endproc\n")
 287     SIZE(X86CompilationCallback_SSE)
 288   );
 289 # else
 290   void X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr);
 291
 292   _declspec(naked) void X86CompilationCallback(void) {
 293     __asm {
 294       push  ebp
 295       mov   ebp, esp
 296       push  eax
 297       push  edx
 298       push  ecx
 299       and   esp, -16
 300       mov   eax, dword ptr [ebp+4]
 301       mov   dword ptr [esp+4], eax
 302       mov   dword ptr [esp], ebp
 303       call  X86CompilationCallback2
 304       mov   esp, ebp
 305       sub   esp, 12
 306       pop   ecx
 307       pop   edx
 308       pop   eax
 309       pop   ebp
 310       ret
 311     }
 312   }
 313
 314 # endif // _MSC_VER
 315
 316 #else // Not an i386 host
 317   void X86CompilationCallback() {
 318     llvm_unreachable("Cannot call X86CompilationCallback() on a non-x86 arch!");
 319   }
 320 #endif
 321 }
 322
 323 /// X86CompilationCallback2 - This is the target-specific function invoked by the
 324 /// function stub when we did not know the real target of a call.  This function
 325 /// must locate the start of the stub or call site and pass it into the JIT
 326 /// compiler function.
 327 extern "C" {
 328 #if !(defined (X86_64_JIT) && defined(_MSC_VER))
 329  // the following function is called only from this translation unit,
 330  // unless we are under 64bit Windows with MSC, where there is
 331  // no support for inline assembly
 332 static
 333 #endif
 334 void ATTRIBUTE_USED
 335 X86CompilationCallback2(intptr_t *StackPtr, intptr_t RetAddr) {
 336   intptr_t *RetAddrLoc = &StackPtr[1];
 337   assert(*RetAddrLoc == RetAddr &&
 338          "Could not find return address on the stack!");
 339
 340   // It's a stub if there is an interrupt marker after the call.
 341   bool isStub = ((unsigned char*)RetAddr)[0] == 0xCD;
 342
 343   // The call instruction should have pushed the return value onto the stack...
 344 #if defined (X86_64_JIT)
 345   RetAddr--;     // Backtrack to the reference itself...
 346 #else
 347   RetAddr -= 4;  // Backtrack to the reference itself...
 348 #endif
 349
 350 #if 0
 351   DEBUG(errs() << "In callback! Addr=" << (void*)RetAddr
 352                << " ESP=" << (void*)StackPtr
 353                << ": Resolving call to function: "
 354                << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
 355 #endif
 356
 357   // Sanity check to make sure this really is a call instruction.
 358 #if defined (X86_64_JIT)
 359   assert(((unsigned char*)RetAddr)[-2] == 0x41 &&"Not a call instr!");
 360   assert(((unsigned char*)RetAddr)[-1] == 0xFF &&"Not a call instr!");
 361 #else
 362   assert(((unsigned char*)RetAddr)[-1] == 0xE8 &&"Not a call instr!");
 363 #endif
 364
 365   intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)RetAddr);
 366
 367   // Rewrite the call target... so that we don't end up here every time we
 368   // execute the call.
 369 #if defined (X86_64_JIT)
 370   if (!isStub)
 371     *(intptr_t *)(RetAddr - 0xa) = NewVal;
 372 #else
 373   *(intptr_t *)RetAddr = (intptr_t)(NewVal-RetAddr-4);
 374 #endif
 375
 376   if (isStub) {
 377     // If this is a stub, rewrite the call into an unconditional branch
 378     // instruction so that two return addresses are not pushed onto the stack
 379     // when the requested function finally gets called.  This also makes the
 380     // 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
 381 #if defined (X86_64_JIT)
 382     // If the target address is within 32-bit range of the stub, use a
 383     // PC-relative branch instead of loading the actual address.  (This is
 384     // considerably shorter than the 64-bit immediate load already there.)
 385     // We assume here intptr_t is 64 bits.
 386     intptr_t diff = NewVal-RetAddr+7;
 387     if (diff >= -2147483648LL && diff <= 2147483647LL) {
 388       *(unsigned char*)(RetAddr-0xc) = 0xE9;
 389       *(intptr_t *)(RetAddr-0xb) = diff & 0xffffffff;
 390     } else {
 391       *(intptr_t *)(RetAddr - 0xa) = NewVal;
 392       ((unsigned char*)RetAddr)[0] = (2 | (4 << 3) | (3 << 6));
 393     }
 394 #else
 395     ((unsigned char*)RetAddr)[-1] = 0xE9;
 396 #endif
 397   }
 398
 399   // Change the return address to reexecute the call instruction...
 400 #if defined (X86_64_JIT)
 401   *RetAddrLoc -= 0xd;
 402 #else
 403   *RetAddrLoc -= 5;
 404 #endif
 405 }
 406 }
 407
 408 TargetJITInfo::LazyResolverFn
 409 X86JITInfo::getLazyResolverFunction(JITCompilerFn F) {
 410   JITCompilerFunction = F;
 411
 412 #if defined (X86_32_JIT) && !defined (_MSC_VER)
 413   if (Subtarget->hasSSE1())
 414     return X86CompilationCallback_SSE;
 415 #endif
 416
 417   return X86CompilationCallback;
 418 }
 419
 420 X86JITInfo::X86JITInfo(X86TargetMachine &tm) : TM(tm) {
 421   Subtarget = &TM.getSubtarget<X86Subtarget>();
 422   useGOT = 0;
 423   TLSOffset = 0;
 424 }
 425
 426 void *X86JITInfo::emitGlobalValueIndirectSym(const GlobalValue* GV, void *ptr,
 427                                              JITCodeEmitter &JCE) {
 428 #if defined (X86_64_JIT)
 429   JCE.startGVStub(GV, 8, 8);
 430   JCE.emitWordLE((unsigned)(intptr_t)ptr);
 431   JCE.emitWordLE((unsigned)(((intptr_t)ptr) >> 32));
 432 #else
 433   JCE.startGVStub(GV, 4, 4);
 434   JCE.emitWordLE((intptr_t)ptr);
 435 #endif
 436   return JCE.finishGVStub(GV);
 437 }
 438
 439 void *X86JITInfo::emitFunctionStub(const Function* F, void *Fn,
 440                                    JITCodeEmitter &JCE) {
 441   // Note, we cast to intptr_t here to silence a -pedantic warning that
 442   // complains about casting a function pointer to a normal pointer.
 443 #if defined (X86_32_JIT) && !defined (_MSC_VER)
 444   bool NotCC = (Fn != (void*)(intptr_t)X86CompilationCallback &&
 445                 Fn != (void*)(intptr_t)X86CompilationCallback_SSE);
 446 #else
 447   bool NotCC = Fn != (void*)(intptr_t)X86CompilationCallback;
 448 #endif
 449   if (NotCC) {
 450 #if defined (X86_64_JIT)
 451     JCE.startGVStub(F, 13, 4);
 452     JCE.emitByte(0x49);          // REX prefix
 453     JCE.emitByte(0xB8+2);        // movabsq r10
 454     JCE.emitWordLE((unsigned)(intptr_t)Fn);
 455     JCE.emitWordLE((unsigned)(((intptr_t)Fn) >> 32));
 456     JCE.emitByte(0x41);          // REX prefix
 457     JCE.emitByte(0xFF);          // jmpq *r10
 458     JCE.emitByte(2 | (4 << 3) | (3 << 6));
 459 #else
 460     JCE.startGVStub(F, 5, 4);
 461     JCE.emitByte(0xE9);
 462     JCE.emitWordLE((intptr_t)Fn-JCE.getCurrentPCValue()-4);
 463 #endif
 464     return JCE.finishGVStub(F);
 465   }
 466
 467 #if defined (X86_64_JIT)
 468   JCE.startGVStub(F, 14, 4);
 469   JCE.emitByte(0x49);          // REX prefix
 470   JCE.emitByte(0xB8+2);        // movabsq r10
 471   JCE.emitWordLE((unsigned)(intptr_t)Fn);
 472   JCE.emitWordLE((unsigned)(((intptr_t)Fn) >> 32));
 473   JCE.emitByte(0x41);          // REX prefix
 474   JCE.emitByte(0xFF);          // callq *r10
 475   JCE.emitByte(2 | (2 << 3) | (3 << 6));
 476 #else
 477   JCE.startGVStub(F, 6, 4);
 478   JCE.emitByte(0xE8);   // Call with 32 bit pc-rel destination...
 479
 480   JCE.emitWordLE((intptr_t)Fn-JCE.getCurrentPCValue()-4);
 481 #endif
 482
 483   JCE.emitByte(0xCD);   // Interrupt - Just a marker identifying the stub!
 484   return JCE.finishGVStub(F);
 485 }
 486
 487 void X86JITInfo::emitFunctionStubAtAddr(const Function* F, void *Fn, void *Stub,
 488                                         JITCodeEmitter &JCE) {
 489   // Note, we cast to intptr_t here to silence a -pedantic warning that
 490   // complains about casting a function pointer to a normal pointer.
 491   JCE.startGVStub(F, Stub, 5);
 492   JCE.emitByte(0xE9);
 493 #if defined (X86_64_JIT) && !defined (NDEBUG)
 494   // Yes, we need both of these casts, or some broken versions of GCC (4.2.4)
 495   // get the signed-ness of the expression wrong.  Go figure.
 496   intptr_t Displacement = (intptr_t)Fn - (intptr_t)JCE.getCurrentPCValue() - 5;
 497   assert(((Displacement << 32) >> 32) == Displacement
 498          && "PIC displacement does not fit in displacement field!");
 499 #endif
 500   JCE.emitWordLE((intptr_t)Fn-JCE.getCurrentPCValue()-4);
 501   JCE.finishGVStub(F);
 502 }
 503
 504 /// getPICJumpTableEntry - Returns the value of the jumptable entry for the
 505 /// specific basic block.
 506 uintptr_t X86JITInfo::getPICJumpTableEntry(uintptr_t BB, uintptr_t Entry) {
 507 #if defined(X86_64_JIT)
 508   return BB - Entry;
 509 #else
 510   return BB - PICBase;
 511 #endif
 512 }
 513
 514 /// relocate - Before the JIT can run a block of code that has been emitted,
 515 /// it must rewrite the code to contain the actual addresses of any
 516 /// referenced global symbols.
 517 void X86JITInfo::relocate(void *Function, MachineRelocation *MR,
 518                           unsigned NumRelocs, unsigned char* GOTBase) {
 519   for (unsigned i = 0; i != NumRelocs; ++i, ++MR) {
 520     void *RelocPos = (char*)Function + MR->getMachineCodeOffset();
 521     intptr_t ResultPtr = (intptr_t)MR->getResultPointer();
 522     switch ((X86::RelocationType)MR->getRelocationType()) {
 523     case X86::reloc_pcrel_word: {
 524       // PC relative relocation, add the relocated value to the value already in
 525       // memory, after we adjust it for where the PC is.
 526       ResultPtr = ResultPtr -(intptr_t)RelocPos - 4 - MR->getConstantVal();
 527       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 528       break;
 529     }
 530     case X86::reloc_picrel_word: {
 531       // PIC base relative relocation, add the relocated value to the value
 532       // already in memory, after we adjust it for where the PIC base is.
 533       ResultPtr = ResultPtr - ((intptr_t)Function + MR->getConstantVal());
 534       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 535       break;
 536     }
 537     case X86::reloc_absolute_word:
 538     case X86::reloc_absolute_word_sext:
 539       // Absolute relocation, just add the relocated value to the value already
 540       // in memory.
 541       *((unsigned*)RelocPos) += (unsigned)ResultPtr;
 542       break;
 543     case X86::reloc_absolute_dword:
 544       *((intptr_t*)RelocPos) += ResultPtr;
 545       break;
 546     }
 547   }
 548 }
 549
 550 char* X86JITInfo::allocateThreadLocalMemory(size_t size) {
 551 #if defined(X86_32_JIT) && !defined(__APPLE__) && !defined(_MSC_VER)
 552   TLSOffset -= size;
 553   return TLSOffset;
 554 #else
 555   llvm_unreachable("Cannot allocate thread local storage on this arch!");
 556   return 0;
 557 #endif
 558 }