linker: Split MachO implementation into new source file

Test Plan: Validate

Reviewers: erikd, austin, simonmar

Reviewed By: simonmar

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2649

1 files changed, 1 insertions, 1226 deletions

diff --git a/rts/Linker.c b/rts/Linker.c
index 3a10bb39b9..7b4753e0ea 100644
--- a/rts/Linker.c
+++ b/rts/Linker.c
@@ -67,18 +67,10 @@
 #  include <windows.h>
 #elif defined(darwin_HOST_OS)
 #  define OBJFORMAT_MACHO
+#  include "linker/MachO.h"
 #  include <regex.h>
 #  include <mach/machine.h>
 #  include <mach-o/fat.h>
-#  include <mach-o/loader.h>
-#  include <mach-o/nlist.h>
-#  include <mach-o/reloc.h>
-#if defined(powerpc_HOST_ARCH)
-#  include <mach-o/ppc/reloc.h>
-#endif
-#if defined(x86_64_HOST_ARCH)
-#  include <mach-o/x86_64/reloc.h>
-#endif
 #endif
 
 #if defined(x86_64_HOST_ARCH) && defined(darwin_HOST_OS)
@@ -204,19 +196,6 @@ static int ocRunInit_ELF        ( ObjectCode* oc );
 #if NEED_SYMBOL_EXTRAS
 static int ocAllocateSymbolExtras_ELF ( ObjectCode* oc );
 #endif
-
-#elif defined(OBJFORMAT_MACHO)
-static int ocVerifyImage_MachO    ( ObjectCode* oc );
-static int ocGetNames_MachO       ( ObjectCode* oc );
-static int ocResolve_MachO        ( ObjectCode* oc );
-static int ocRunInit_MachO        ( ObjectCode* oc );
-static int machoGetMisalignment( FILE * );
-#if NEED_SYMBOL_EXTRAS
-static int ocAllocateSymbolExtras_MachO ( ObjectCode* oc );
-#endif
-#ifdef powerpc_HOST_ARCH
-static void machoInitSymbolsWithoutUnderscore( void );
-#endif
 #endif
 
 /* on x86_64 we have a problem with relocating symbol references in
@@ -3986,1207 +3965,3 @@ static int ocAllocateSymbolExtras_ELF( ObjectCode *oc )
  * Mach-O specifics
  * ------------------------------------------------------------------------*/
 
-#if defined(OBJFORMAT_MACHO)
-
-/*
-  Support for MachO linking on Darwin/MacOS X
-  by Wolfgang Thaller (wolfgang.thaller@gmx.net)
-
-  I hereby formally apologize for the hackish nature of this code.
-  Things that need to be done:
-  *) implement ocVerifyImage_MachO
-  *) add still more sanity checks.
-*/
-
-#if x86_64_HOST_ARCH || powerpc64_HOST_ARCH
-#define mach_header mach_header_64
-#define segment_command segment_command_64
-#define section section_64
-#define nlist nlist_64
-#endif
-
-#ifdef powerpc_HOST_ARCH
-static int
-ocAllocateSymbolExtras_MachO(ObjectCode* oc)
-{
-    struct mach_header *header = (struct mach_header *) oc->image;
-    struct load_command *lc = (struct load_command *) (header + 1);
-    unsigned i;
-
-    IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: start\n"));
-
-    for (i = 0; i < header->ncmds; i++) {
-        if (lc->cmd == LC_SYMTAB) {
-
-                // Find out the first and last undefined external
-                // symbol, so we don't have to allocate too many
-            // jump islands/GOT entries.
-
-            struct symtab_command *symLC = (struct symtab_command *) lc;
-            unsigned min = symLC->nsyms, max = 0;
-            struct nlist *nlist =
-                symLC ? (struct nlist*) ((char*) oc->image + symLC->symoff)
-                      : NULL;
-
-            for (i = 0; i < symLC->nsyms; i++) {
-
-                if (nlist[i].n_type & N_STAB) {
-                    ;
-                } else if (nlist[i].n_type & N_EXT) {
-
-                    if((nlist[i].n_type & N_TYPE) == N_UNDF
-                        && (nlist[i].n_value == 0)) {
-
-                        if (i < min) {
-                            min = i;
-                        }
-
-                        if (i > max) {
-                            max = i;
-                    }
-                }
-            }
-            }
-
-            if (max >= min) {
-                return ocAllocateSymbolExtras(oc, max - min + 1, min);
-            }
-
-            break;
-        }
-
-        lc = (struct load_command *) ( ((char *)lc) + lc->cmdsize );
-    }
-
-    return ocAllocateSymbolExtras(oc,0,0);
-}
-
-#endif
-#ifdef x86_64_HOST_ARCH
-static int
-ocAllocateSymbolExtras_MachO(ObjectCode* oc)
-{
-    struct mach_header *header = (struct mach_header *) oc->image;
-    struct load_command *lc = (struct load_command *) (header + 1);
-    unsigned i;
-
-    IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: start\n"));
-
-    for (i = 0; i < header->ncmds; i++) {
-        if (lc->cmd == LC_SYMTAB) {
-
-                // Just allocate one entry for every symbol
-            struct symtab_command *symLC = (struct symtab_command *) lc;
-
-            IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: allocate %d symbols\n", symLC->nsyms));
-            IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: done\n"));
-            return ocAllocateSymbolExtras(oc, symLC->nsyms, 0);
-        }
-
-        lc = (struct load_command *) ( ((char *)lc) + lc->cmdsize );
-    }
-
-    IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: allocated no symbols\n"));
-    IF_DEBUG(linker, debugBelch("ocAllocateSymbolExtras_MachO: done\n"));
-    return ocAllocateSymbolExtras(oc,0,0);
-}
-#endif
-
-static int
-ocVerifyImage_MachO(ObjectCode * oc)
-{
-    char *image = (char*) oc->image;
-    struct mach_header *header = (struct mach_header*) image;
-
-    IF_DEBUG(linker, debugBelch("ocVerifyImage_MachO: start\n"));
-
-#if x86_64_HOST_ARCH || powerpc64_HOST_ARCH
-    if(header->magic != MH_MAGIC_64) {
-        errorBelch("Could not load image %s: bad magic!\n"
-                   "  Expected %08x (64bit), got %08x%s\n",
-                   oc->fileName, MH_MAGIC_64, header->magic,
-                   header->magic == MH_MAGIC ? " (32bit)." : ".");
-        return 0;
-    }
-#else
-    if(header->magic != MH_MAGIC) {
-        errorBelch("Could not load image %s: bad magic!\n"
-                   "  Expected %08x (32bit), got %08x%s\n",
-                   oc->fileName, MH_MAGIC, header->magic,
-                   header->magic == MH_MAGIC_64 ? " (64bit)." : ".");
-        return 0;
-    }
-#endif
-
-    // FIXME: do some more verifying here
-    IF_DEBUG(linker, debugBelch("ocVerifyImage_MachO: done\n"));
-    return 1;
-}
-
-static int
-resolveImports(
-    ObjectCode* oc,
-    char *image,
-    struct symtab_command *symLC,
-    struct section *sect,    // ptr to lazy or non-lazy symbol pointer section
-    unsigned long *indirectSyms,
-    struct nlist *nlist)
-{
-    unsigned i;
-    size_t itemSize = 4;
-
-    IF_DEBUG(linker, debugBelch("resolveImports: start\n"));
-
-#if i386_HOST_ARCH
-    int isJumpTable = 0;
-
-    if (strcmp(sect->sectname,"__jump_table") == 0) {
-        isJumpTable = 1;
-        itemSize = 5;
-        ASSERT(sect->reserved2 == itemSize);
-    }
-
-#endif
-
-    for(i = 0; i * itemSize < sect->size; i++)
-    {
-        // according to otool, reserved1 contains the first index into the indirect symbol table
-        struct nlist *symbol = &nlist[indirectSyms[sect->reserved1+i]];
-        SymbolName* nm = image + symLC->stroff + symbol->n_un.n_strx;
-        SymbolAddr* addr = NULL;
-
-        IF_DEBUG(linker, debugBelch("resolveImports: resolving %s\n", nm));
-
-        if ((symbol->n_type & N_TYPE) == N_UNDF
-            && (symbol->n_type & N_EXT) && (symbol->n_value != 0)) {
-            addr = (SymbolAddr*) (symbol->n_value);
-            IF_DEBUG(linker, debugBelch("resolveImports: undefined external %s has value %p\n", nm, addr));
-        } else {
-            addr = lookupSymbol_(nm);
-            IF_DEBUG(linker, debugBelch("resolveImports: looking up %s, %p\n", nm, addr));
-        }
-
-        if (addr == NULL)
-        {
-            errorBelch("\nlookupSymbol failed in resolveImports\n"
-                       "%s: unknown symbol `%s'", oc->fileName, nm);
-            return 0;
-        }
-        ASSERT(addr);
-
-#if i386_HOST_ARCH
-        if (isJumpTable) {
-            checkProddableBlock(oc,image + sect->offset + i*itemSize, 5);
-
-            *(image + sect->offset + i * itemSize) = 0xe9; // jmp opcode
-            *(unsigned*)(image + sect->offset + i*itemSize + 1)
-                = (SymbolAddr*)addr - (image + sect->offset + i*itemSize + 5);
-        }
-        else
-#endif
-        {
-            checkProddableBlock(oc,
-                                ((void**)(image + sect->offset)) + i,
-                                sizeof(void *));
-            ((void**)(image + sect->offset))[i] = addr;
-        }
-    }
-
-    IF_DEBUG(linker, debugBelch("resolveImports: done\n"));
-    return 1;
-}
-
-static unsigned long
-relocateAddress(
-    ObjectCode* oc,
-    int nSections,
-    struct section* sections,
-    unsigned long address)
-{
-    int i;
-    IF_DEBUG(linker, debugBelch("relocateAddress: start\n"));
-    for (i = 0; i < nSections; i++)
-    {
-            IF_DEBUG(linker, debugBelch("    relocating address in section %d\n", i));
-        if (sections[i].addr <= address
-            && address < sections[i].addr + sections[i].size)
-        {
-            return (unsigned long)oc->image
-                    + sections[i].offset + address - sections[i].addr;
-        }
-    }
-    barf("Invalid Mach-O file:"
-         "Address out of bounds while relocating object file");
-    return 0;
-}
-
-static int
-relocateSection(
-    ObjectCode* oc,
-    char *image,
-    struct symtab_command *symLC, struct nlist *nlist,
-    int nSections, struct section* sections, struct section *sect)
-{
-    struct relocation_info *relocs;
-    int i, n;
-
-    IF_DEBUG(linker, debugBelch("relocateSection: start\n"));
-
-    if(!strcmp(sect->sectname,"__la_symbol_ptr"))
-        return 1;
-    else if(!strcmp(sect->sectname,"__nl_symbol_ptr"))
-        return 1;
-    else if(!strcmp(sect->sectname,"__la_sym_ptr2"))
-        return 1;
-    else if(!strcmp(sect->sectname,"__la_sym_ptr3"))
-        return 1;
-
-    n = sect->nreloc;
-    IF_DEBUG(linker, debugBelch("relocateSection: number of relocations: %d\n", n));
-
-    relocs = (struct relocation_info*) (image + sect->reloff);
-
-    for(i = 0; i < n; i++)
-    {
-#ifdef x86_64_HOST_ARCH
-        struct relocation_info *reloc = &relocs[i];
-
-        char    *thingPtr = image + sect->offset + reloc->r_address;
-        uint64_t thing;
-        /* We shouldn't need to initialise this, but gcc on OS X 64 bit
-           complains that it may be used uninitialized if we don't */
-        uint64_t value = 0;
-        uint64_t baseValue;
-        int type = reloc->r_type;
-
-        IF_DEBUG(linker, debugBelch("relocateSection: relocation %d\n", i));
-        IF_DEBUG(linker, debugBelch("               : type      = %d\n", reloc->r_type));
-        IF_DEBUG(linker, debugBelch("               : address   = %d\n", reloc->r_address));
-        IF_DEBUG(linker, debugBelch("               : symbolnum = %u\n", reloc->r_symbolnum));
-        IF_DEBUG(linker, debugBelch("               : pcrel     = %d\n", reloc->r_pcrel));
-        IF_DEBUG(linker, debugBelch("               : length    = %d\n", reloc->r_length));
-        IF_DEBUG(linker, debugBelch("               : extern    = %d\n", reloc->r_extern));
-        IF_DEBUG(linker, debugBelch("               : type      = %d\n", reloc->r_type));
-
-        switch(reloc->r_length)
-        {
-            case 0:
-                checkProddableBlock(oc,thingPtr,1);
-                thing = *(uint8_t*)thingPtr;
-                baseValue = (uint64_t)thingPtr + 1;
-                break;
-            case 1:
-                checkProddableBlock(oc,thingPtr,2);
-                thing = *(uint16_t*)thingPtr;
-                baseValue = (uint64_t)thingPtr + 2;
-                break;
-            case 2:
-                checkProddableBlock(oc,thingPtr,4);
-                thing = *(uint32_t*)thingPtr;
-                baseValue = (uint64_t)thingPtr + 4;
-                break;
-            case 3:
-                checkProddableBlock(oc,thingPtr,8);
-                thing = *(uint64_t*)thingPtr;
-                baseValue = (uint64_t)thingPtr + 8;
-                break;
-            default:
-                barf("Unknown size.");
-        }
-
-        IF_DEBUG(linker,
-                 debugBelch("relocateSection: length = %d, thing = %" PRId64 ", baseValue = %p\n",
-                            reloc->r_length, thing, (char *)baseValue));
-
-        if (type == X86_64_RELOC_GOT
-         || type == X86_64_RELOC_GOT_LOAD)
-        {
-            struct nlist *symbol = &nlist[reloc->r_symbolnum];
-            SymbolName* nm = image + symLC->stroff + symbol->n_un.n_strx;
-            SymbolAddr* addr = NULL;
-
-            IF_DEBUG(linker, debugBelch("relocateSection: making jump island for %s, extern = %d, X86_64_RELOC_GOT\n", nm, reloc->r_extern));
-
-            ASSERT(reloc->r_extern);
-            if (reloc->r_extern == 0) {
-                    errorBelch("\nrelocateSection: global offset table relocation for symbol with r_extern == 0\n");
-            }
-
-            if (symbol->n_type & N_EXT) {
-                    // The external bit is set, meaning the symbol is exported,
-                    // and therefore can be looked up in this object module's
-                    // symtab, or it is undefined, meaning dlsym must be used
-                    // to resolve it.
-
-                    addr = lookupSymbol_(nm);
-                    IF_DEBUG(linker, debugBelch("relocateSection: looked up %s, "
-                                                "external X86_64_RELOC_GOT or X86_64_RELOC_GOT_LOAD\n", nm));
-                    IF_DEBUG(linker, debugBelch("               : addr = %p\n", addr));
-
-                    if (addr == NULL) {
-                            errorBelch("\nlookupSymbol failed in relocateSection (RELOC_GOT)\n"
-                                       "%s: unknown symbol `%s'", oc->fileName, nm);
-                            return 0;
-                    }
-            } else {
-                    IF_DEBUG(linker, debugBelch("relocateSection: %s is not an exported symbol\n", nm));
-
-                    // The symbol is not exported, or defined in another
-                    // module, so it must be in the current object module,
-                    // at the location given by the section index and
-                    // symbol address (symbol->n_value)
-
-                    if ((symbol->n_type & N_TYPE) == N_SECT) {
-                            addr = (void *)relocateAddress(oc, nSections, sections, symbol->n_value);
-                            IF_DEBUG(linker, debugBelch("relocateSection: calculated relocation %p of "
-                                                        "non-external X86_64_RELOC_GOT or X86_64_RELOC_GOT_LOAD\n",
-                                                        (void *)symbol->n_value));
-                            IF_DEBUG(linker, debugBelch("               : addr = %p\n", addr));
-                    } else {
-                            errorBelch("\nrelocateSection: %s is not exported,"
-                                       " and should be defined in a section, but isn't!\n", nm);
-                    }
-            }
-
-            value = (uint64_t) &makeSymbolExtra(oc, reloc->r_symbolnum, (unsigned long)addr)->addr;
-
-            type = X86_64_RELOC_SIGNED;
-        }
-        else if (reloc->r_extern)
-        {
-            struct nlist *symbol = &nlist[reloc->r_symbolnum];
-            SymbolName* nm = image + symLC->stroff + symbol->n_un.n_strx;
-            SymbolAddr* addr = NULL;
-
-            IF_DEBUG(linker, debugBelch("relocateSection: looking up external symbol %s\n", nm));
-            IF_DEBUG(linker, debugBelch("               : type  = %d\n", symbol->n_type));
-            IF_DEBUG(linker, debugBelch("               : sect  = %d\n", symbol->n_sect));
-            IF_DEBUG(linker, debugBelch("               : desc  = %d\n", symbol->n_desc));
-            IF_DEBUG(linker, debugBelch("               : value = %p\n", (void *)symbol->n_value));
-
-            if ((symbol->n_type & N_TYPE) == N_SECT) {
-                value = relocateAddress(oc, nSections, sections,
-                                        symbol->n_value);
-                IF_DEBUG(linker, debugBelch("relocateSection, defined external symbol %s, relocated address %p\n", nm, (void *)value));
-            }
-            else {
-                addr = lookupSymbol_(nm);
-                if (addr == NULL)
-                {
-                     errorBelch("\nlookupSymbol failed in relocateSection (relocate external)\n"
-                                "%s: unknown symbol `%s'", oc->fileName, nm);
-                     return 0;
-                }
-
-                value = (uint64_t) addr;
-                IF_DEBUG(linker, debugBelch("relocateSection: external symbol %s, address %p\n", nm, (void *)value));
-            }
-        }
-        else
-        {
-            // If the relocation is not through the global offset table
-            // or external, then set the value to the baseValue.  This
-            // will leave displacements into the __const section
-            // unchanged (as they ought to be).
-
-            value = baseValue;
-        }
-
-        IF_DEBUG(linker, debugBelch("relocateSection: value = %p\n", (void *)value));
-
-        if (type == X86_64_RELOC_BRANCH)
-        {
-            if((int32_t)(value - baseValue) != (int64_t)(value - baseValue))
-            {
-                ASSERT(reloc->r_extern);
-                value = (uint64_t) &makeSymbolExtra(oc, reloc->r_symbolnum, value)
-                                        -> jumpIsland;
-            }
-            ASSERT((int32_t)(value - baseValue) == (int64_t)(value - baseValue));
-            type = X86_64_RELOC_SIGNED;
-        }
-
-        switch(type)
-        {
-            case X86_64_RELOC_UNSIGNED:
-                ASSERT(!reloc->r_pcrel);
-                thing += value;
-                break;
-            case X86_64_RELOC_SIGNED:
-            case X86_64_RELOC_SIGNED_1:
-            case X86_64_RELOC_SIGNED_2:
-            case X86_64_RELOC_SIGNED_4:
-                ASSERT(reloc->r_pcrel);
-                thing += value - baseValue;
-                break;
-            case X86_64_RELOC_SUBTRACTOR:
-                ASSERT(!reloc->r_pcrel);
-                thing -= value;
-                break;
-            default:
-                barf("unkown relocation");
-        }
-
-        switch(reloc->r_length)
-        {
-            case 0:
-                *(uint8_t*)thingPtr = thing;
-                break;
-            case 1:
-                *(uint16_t*)thingPtr = thing;
-                break;
-            case 2:
-                *(uint32_t*)thingPtr = thing;
-                break;
-            case 3:
-                *(uint64_t*)thingPtr = thing;
-                break;
-        }
-#else
-        if(relocs[i].r_address & R_SCATTERED)
-        {
-            struct scattered_relocation_info *scat =
-                (struct scattered_relocation_info*) &relocs[i];
-
-            if(!scat->r_pcrel)
-            {
-                if(scat->r_length == 2)
-                {
-                    unsigned long word = 0;
-                    unsigned long* wordPtr = (unsigned long*) (image + sect->offset + scat->r_address);
-
-                    /* In this check we assume that sizeof(unsigned long) = 2 * sizeof(unsigned short)
-                       on powerpc_HOST_ARCH */
-                    checkProddableBlock(oc,wordPtr,sizeof(unsigned long));
-
-                    // Note on relocation types:
-                    // i386 uses the GENERIC_RELOC_* types,
-                    // while ppc uses special PPC_RELOC_* types.
-                    // *_RELOC_VANILLA and *_RELOC_PAIR have the same value
-                    // in both cases, all others are different.
-                    // Therefore, we use GENERIC_RELOC_VANILLA
-                    // and GENERIC_RELOC_PAIR instead of the PPC variants,
-                    // and use #ifdefs for the other types.
-
-                    // Step 1: Figure out what the relocated value should be
-                    if (scat->r_type == GENERIC_RELOC_VANILLA) {
-                        word = *wordPtr
-                             + (unsigned long) relocateAddress(oc,
-                                                                nSections,
-                                                                sections,
-                                                                scat->r_value)
-                                        - scat->r_value;
-                    }
-#ifdef powerpc_HOST_ARCH
-                    else if(scat->r_type == PPC_RELOC_SECTDIFF
-                        || scat->r_type == PPC_RELOC_LO16_SECTDIFF
-                        || scat->r_type == PPC_RELOC_HI16_SECTDIFF
-                        || scat->r_type == PPC_RELOC_HA16_SECTDIFF
-                        || scat->r_type == PPC_RELOC_LOCAL_SECTDIFF)
-#else
-                    else if(scat->r_type == GENERIC_RELOC_SECTDIFF
-                        || scat->r_type == GENERIC_RELOC_LOCAL_SECTDIFF)
-#endif
-                    {
-                        struct scattered_relocation_info *pair =
-                                (struct scattered_relocation_info*) &relocs[i+1];
-
-                        if (!pair->r_scattered || pair->r_type != GENERIC_RELOC_PAIR) {
-                            barf("Invalid Mach-O file: "
-                                 "RELOC_*_SECTDIFF not followed by RELOC_PAIR");
-                        }
-
-                        word = (unsigned long)
-                               (relocateAddress(oc, nSections, sections, scat->r_value)
-                              - relocateAddress(oc, nSections, sections, pair->r_value));
-                        i++;
-                    }
-#ifdef powerpc_HOST_ARCH
-                    else if(scat->r_type == PPC_RELOC_HI16
-                         || scat->r_type == PPC_RELOC_LO16
-                         || scat->r_type == PPC_RELOC_HA16
-                         || scat->r_type == PPC_RELOC_LO14)
-                    {   // these are generated by label+offset things
-                        struct relocation_info *pair = &relocs[i+1];
-
-                        if ((pair->r_address & R_SCATTERED) || pair->r_type != PPC_RELOC_PAIR) {
-                            barf("Invalid Mach-O file: "
-                                 "PPC_RELOC_* not followed by PPC_RELOC_PAIR");
-                        }
-
-                        if(scat->r_type == PPC_RELOC_LO16)
-                        {
-                            word = ((unsigned short*) wordPtr)[1];
-                            word |= ((unsigned long) relocs[i+1].r_address & 0xFFFF) << 16;
-                        }
-                        else if(scat->r_type == PPC_RELOC_LO14)
-                        {
-                            barf("Unsupported Relocation: PPC_RELOC_LO14");
-                            word = ((unsigned short*) wordPtr)[1] & 0xFFFC;
-                            word |= ((unsigned long) relocs[i+1].r_address & 0xFFFF) << 16;
-                        }
-                        else if(scat->r_type == PPC_RELOC_HI16)
-                        {
-                            word = ((unsigned short*) wordPtr)[1] << 16;
-                            word |= ((unsigned long) relocs[i+1].r_address & 0xFFFF);
-                        }
-                        else if(scat->r_type == PPC_RELOC_HA16)
-                        {
-                            word = ((unsigned short*) wordPtr)[1] << 16;
-                            word += ((short)relocs[i+1].r_address & (short)0xFFFF);
-                        }
-
-
-                        word += (unsigned long) relocateAddress(oc, nSections, sections, scat->r_value)
-                                                - scat->r_value;
-
-                        i++;
-                    }
- #endif
-                    else {
-                        barf ("Don't know how to handle this Mach-O "
-                              "scattered relocation entry: "
-                              "object file %s; entry type %ld; "
-                              "address %#lx\n",
-                              OC_INFORMATIVE_FILENAME(oc),
-                              scat->r_type,
-                              scat->r_address);
-                        return 0;
-                     }
-
-#ifdef powerpc_HOST_ARCH
-                    if(scat->r_type == GENERIC_RELOC_VANILLA
-                        || scat->r_type == PPC_RELOC_SECTDIFF)
-#else
-                    if(scat->r_type == GENERIC_RELOC_VANILLA
-                        || scat->r_type == GENERIC_RELOC_SECTDIFF
-                        || scat->r_type == GENERIC_RELOC_LOCAL_SECTDIFF)
-#endif
-                    {
-                        *wordPtr = word;
-                    }
-#ifdef powerpc_HOST_ARCH
-                    else if (scat->r_type == PPC_RELOC_LO16_SECTDIFF
-                          || scat->r_type == PPC_RELOC_LO16)
-                    {
-                        ((unsigned short*) wordPtr)[1] = word & 0xFFFF;
-                    }
-                    else if (scat->r_type == PPC_RELOC_HI16_SECTDIFF
-                          || scat->r_type == PPC_RELOC_HI16)
-                    {
-                        ((unsigned short*) wordPtr)[1] = (word >> 16) & 0xFFFF;
-                    }
-                    else if (scat->r_type == PPC_RELOC_HA16_SECTDIFF
-                          || scat->r_type == PPC_RELOC_HA16)
-                    {
-                        ((unsigned short*) wordPtr)[1] = ((word >> 16) & 0xFFFF)
-                            + ((word & (1<<15)) ? 1 : 0);
-                    }
-#endif
-                }
-                else
-                {
-                    barf("Can't handle Mach-O scattered relocation entry "
-                         "with this r_length tag: "
-                         "object file %s; entry type %ld; "
-                         "r_length tag %ld; address %#lx\n",
-                         OC_INFORMATIVE_FILENAME(oc),
-                         scat->r_type,
-                         scat->r_length,
-                         scat->r_address);
-                    return 0;
-                }
-            }
-            else /* scat->r_pcrel */
-            {
-                barf("Don't know how to handle *PC-relative* Mach-O "
-                     "scattered relocation entry: "
-                     "object file %s; entry type %ld; address %#lx\n",
-                     OC_INFORMATIVE_FILENAME(oc),
-                     scat->r_type,
-                     scat->r_address);
-               return 0;
-            }
-
-        }
-        else /* !(relocs[i].r_address & R_SCATTERED) */
-        {
-            struct relocation_info *reloc = &relocs[i];
-            if (reloc->r_pcrel && !reloc->r_extern) {
-                IF_DEBUG(linker, debugBelch("relocateSection: pc relative but not external, skipping\n"));
-                continue;
-            }
-
-            if (reloc->r_length == 2) {
-                unsigned long word = 0;
-#ifdef powerpc_HOST_ARCH
-                unsigned long jumpIsland = 0;
-                long offsetToJumpIsland = 0xBADBAD42; // initialise to bad value
-                                                      // to avoid warning and to catch
-                                                      // bugs.
-#endif
-
-                unsigned long* wordPtr = (unsigned long*) (image + sect->offset + reloc->r_address);
-
-                /* In this check we assume that sizeof(unsigned long) = 2 * sizeof(unsigned short)
-                   on powerpc_HOST_ARCH */
-                checkProddableBlock(oc,wordPtr, sizeof(unsigned long));
-
-                if (reloc->r_type == GENERIC_RELOC_VANILLA) {
-                    word = *wordPtr;
-                }
-#ifdef powerpc_HOST_ARCH
-                else if (reloc->r_type == PPC_RELOC_LO16) {
-                    word = ((unsigned short*) wordPtr)[1];
-                    word |= ((unsigned long) relocs[i+1].r_address & 0xFFFF) << 16;
-                }
-                else if (reloc->r_type == PPC_RELOC_HI16) {
-                    word = ((unsigned short*) wordPtr)[1] << 16;
-                    word |= ((unsigned long) relocs[i+1].r_address & 0xFFFF);
-                }
-                else if (reloc->r_type == PPC_RELOC_HA16) {
-                    word = ((unsigned short*) wordPtr)[1] << 16;
-                    word += ((short)relocs[i+1].r_address & (short)0xFFFF);
-                }
-                else if (reloc->r_type == PPC_RELOC_BR24) {
-                    word = *wordPtr;
-                    word = (word & 0x03FFFFFC) | ((word & 0x02000000) ? 0xFC000000 : 0);
-                }
-#endif
-                else {
-                    barf("Can't handle this Mach-O relocation entry "
-                         "(not scattered): "
-                         "object file %s; entry type %ld; address %#lx\n",
-                         OC_INFORMATIVE_FILENAME(oc),
-                         reloc->r_type,
-                         reloc->r_address);
-                    return 0;
-                }
-
-                if (!reloc->r_extern) {
-                    long delta = sections[reloc->r_symbolnum-1].offset
-                        - sections[reloc->r_symbolnum-1].addr
-                        + ((long) image);
-
-                    word += delta;
-                }
-                else {
-                    struct nlist *symbol = &nlist[reloc->r_symbolnum];
-                    char *nm = image + symLC->stroff + symbol->n_un.n_strx;
-                    void *symbolAddress = lookupSymbol_(nm);
-
-                    if (!symbolAddress) {
-                        errorBelch("\nunknown symbol `%s'", nm);
-                        return 0;
-                    }
-
-                    if (reloc->r_pcrel) {
-#ifdef powerpc_HOST_ARCH
-                            // In the .o file, this should be a relative jump to NULL
-                            // and we'll change it to a relative jump to the symbol
-                        ASSERT(word + reloc->r_address == 0);
-                        jumpIsland = (unsigned long)
-                                        &makeSymbolExtra(oc,
-                                                         reloc->r_symbolnum,
-                                                         (unsigned long) symbolAddress)
-                                         -> jumpIsland;
-                        if (jumpIsland != 0) {
-                            offsetToJumpIsland = word + jumpIsland
-                                - (((long)image) + sect->offset - sect->addr);
-                        }
-#endif
-                        word += (unsigned long) symbolAddress
-                                - (((long)image) + sect->offset - sect->addr);
-                    }
-                    else {
-                        word += (unsigned long) symbolAddress;
-                    }
-                }
-
-                if (reloc->r_type == GENERIC_RELOC_VANILLA) {
-                    *wordPtr = word;
-                    continue;
-                }
-#ifdef powerpc_HOST_ARCH
-                else if(reloc->r_type == PPC_RELOC_LO16)
-                {
-                    ((unsigned short*) wordPtr)[1] = word & 0xFFFF;
-                    i++;
-                    continue;
-                }
-                else if(reloc->r_type == PPC_RELOC_HI16)
-                {
-                    ((unsigned short*) wordPtr)[1] = (word >> 16) & 0xFFFF;
-                    i++;
-                    continue;
-                }
-                else if(reloc->r_type == PPC_RELOC_HA16)
-                {
-                    ((unsigned short*) wordPtr)[1] = ((word >> 16) & 0xFFFF)
-                        + ((word & (1<<15)) ? 1 : 0);
-                    i++;
-                    continue;
-                }
-                else if(reloc->r_type == PPC_RELOC_BR24)
-                {
-                    if ((word & 0x03) != 0) {
-                        barf("%s: unconditional relative branch with a displacement "
-                             "which isn't a multiple of 4 bytes: %#lx",
-                             OC_INFORMATIVE_FILENAME(oc),
-                             word);
-                    }
-
-                    if((word & 0xFE000000) != 0xFE000000 &&
-                        (word & 0xFE000000) != 0x00000000) {
-                        // The branch offset is too large.
-                        // Therefore, we try to use a jump island.
-                        if (jumpIsland == 0) {
-                            barf("%s: unconditional relative branch out of range: "
-                                 "no jump island available: %#lx",
-                                 OC_INFORMATIVE_FILENAME(oc),
-                                 word);
-                        }
-
-                        word = offsetToJumpIsland;
-
-                        if((word & 0xFE000000) != 0xFE000000 &&
-                            (word & 0xFE000000) != 0x00000000) {
-                            barf("%s: unconditional relative branch out of range: "
-                                 "jump island out of range: %#lx",
-                                 OC_INFORMATIVE_FILENAME(oc),
-                                 word);
-                    }
-                    }
-                    *wordPtr = (*wordPtr & 0xFC000003) | (word & 0x03FFFFFC);
-                    continue;
-                }
-#endif
-            }
-            else
-            {
-                 barf("Can't handle Mach-O relocation entry (not scattered) "
-                      "with this r_length tag: "
-                      "object file %s; entry type %ld; "
-                      "r_length tag %ld; address %#lx\n",
-                      OC_INFORMATIVE_FILENAME(oc),
-                      reloc->r_type,
-                      reloc->r_length,
-                      reloc->r_address);
-                 return 0;
-            }
-        }
-#endif
-    }
-
-    IF_DEBUG(linker, debugBelch("relocateSection: done\n"));
-    return 1;
-}
-
-static int
-ocGetNames_MachO(ObjectCode* oc)
-{
-    char *image = (char*) oc->image;
-    struct mach_header *header = (struct mach_header*) image;
-    struct load_command *lc = (struct load_command*) (image + sizeof(struct mach_header));
-    unsigned i,curSymbol = 0;
-    struct segment_command *segLC = NULL;
-    struct section *sections;
-    struct symtab_command *symLC = NULL;
-    struct nlist *nlist;
-    unsigned long commonSize = 0;
-    SymbolAddr* commonStorage = NULL;
-    unsigned long commonCounter;
-
-    IF_DEBUG(linker,debugBelch("ocGetNames_MachO: start\n"));
-
-    for(i=0;i<header->ncmds;i++)
-    {
-        if (lc->cmd == LC_SEGMENT || lc->cmd == LC_SEGMENT_64) {
-            segLC = (struct segment_command*) lc;
-        }
-        else if (lc->cmd == LC_SYMTAB) {
-            symLC = (struct symtab_command*) lc;
-        }
-
-        lc = (struct load_command *) ( ((char*)lc) + lc->cmdsize );
-    }
-
-    sections = (struct section*) (segLC+1);
-    nlist = symLC ? (struct nlist*) (image + symLC->symoff)
-                  : NULL;
-
-    if (!segLC) {
-        barf("ocGetNames_MachO: no segment load command");
-    }
-
-    Section *secArray;
-    secArray = (Section*)stgCallocBytes(
-         sizeof(Section),
-         segLC->nsects,
-         "ocGetNames_MachO(sections)");
-   oc->sections = secArray;
-   oc->n_sections = segLC->nsects;
-
-    IF_DEBUG(linker, debugBelch("ocGetNames_MachO: will load %d sections\n", segLC->nsects));
-    for(i=0;i<segLC->nsects;i++)
-    {
-        IF_DEBUG(linker, debugBelch("ocGetNames_MachO: section %d\n", i));
-
-        if (sections[i].size == 0) {
-            IF_DEBUG(linker, debugBelch("ocGetNames_MachO: found a zero length section, skipping\n"));
-            continue;
-        }
-
-        if((sections[i].flags & SECTION_TYPE) == S_ZEROFILL) {
-            char * zeroFillArea;
-            if (RTS_LINKER_USE_MMAP) {
-                zeroFillArea = mmapForLinker(sections[i].size, MAP_ANONYMOUS,
-                                            -1, 0);
-                if (zeroFillArea == NULL) return 0;
-                memset(zeroFillArea, 0, sections[i].size);
-            }
-            else {
-                zeroFillArea = stgCallocBytes(1,sections[i].size,
-                                      "ocGetNames_MachO(common symbols)");
-            }
-            sections[i].offset = zeroFillArea - image;
-        }
-
-        SectionKind kind = SECTIONKIND_OTHER;
-
-        if (0==strcmp(sections[i].sectname,"__text")) {
-            kind = SECTIONKIND_CODE_OR_RODATA;
-        }
-        else if (0==strcmp(sections[i].sectname,"__const") ||
-                 0==strcmp(sections[i].sectname,"__data") ||
-                 0==strcmp(sections[i].sectname,"__bss") ||
-                 0==strcmp(sections[i].sectname,"__common") ||
-                 0==strcmp(sections[i].sectname,"__mod_init_func")) {
-            kind = SECTIONKIND_RWDATA;
-        }
-
-        addSection(&secArray[i], kind, SECTION_NOMEM,
-                   (void *)(image + sections[i].offset),
-                   sections[i].size,
-                   0, 0, 0);
-
-        addProddableBlock(oc,
-                          (void *) (image + sections[i].offset),
-                                        sections[i].size);
-    }
-
-        // count external symbols defined here
-    oc->n_symbols = 0;
-    if (symLC) {
-        for (i = 0; i < symLC->nsyms; i++) {
-            if (nlist[i].n_type & N_STAB) {
-                ;
-            }
-            else if(nlist[i].n_type & N_EXT)
-            {
-                if((nlist[i].n_type & N_TYPE) == N_UNDF
-                    && (nlist[i].n_value != 0))
-                {
-                    commonSize += nlist[i].n_value;
-                    oc->n_symbols++;
-                }
-                else if((nlist[i].n_type & N_TYPE) == N_SECT)
-                    oc->n_symbols++;
-            }
-        }
-    }
-    IF_DEBUG(linker, debugBelch("ocGetNames_MachO: %d external symbols\n", oc->n_symbols));
-    oc->symbols = stgMallocBytes(oc->n_symbols * sizeof(SymbolName*),
-                                   "ocGetNames_MachO(oc->symbols)");
-
-    if(symLC)
-    {
-        for(i=0;i<symLC->nsyms;i++)
-        {
-            if(nlist[i].n_type & N_STAB)
-                ;
-            else if((nlist[i].n_type & N_TYPE) == N_SECT)
-            {
-                if(nlist[i].n_type & N_EXT)
-                {
-                    SymbolName* nm = image + symLC->stroff + nlist[i].n_un.n_strx;
-                    if ((nlist[i].n_desc & N_WEAK_DEF) && lookupSymbol_(nm)) {
-                        // weak definition, and we already have a definition
-                        IF_DEBUG(linker, debugBelch("    weak: %s\n", nm));
-                    }
-                    else
-                    {
-                            IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting %s\n", nm));
-                            SymbolAddr* addr = image
-                                       + sections[nlist[i].n_sect - 1].offset
-                                       - sections[nlist[i].n_sect - 1].addr
-                                       + nlist[i].n_value;
-
-                            ghciInsertSymbolTable( oc->fileName
-                                                 , symhash
-                                                 , nm
-                                                 , addr
-                                                 , HS_BOOL_FALSE
-                                                 , oc);
-
-                            oc->symbols[curSymbol] = nm;
-                            curSymbol++;
-                    }
-                }
-                else
-                {
-                    IF_DEBUG(linker, debugBelch("ocGetNames_MachO: \t...not external, skipping\n"));
-                }
-            }
-            else
-            {
-                IF_DEBUG(linker, debugBelch("ocGetNames_MachO: \t...not defined in this section, skipping\n"));
-            }
-        }
-    }
-
-    commonStorage = stgCallocBytes(1,commonSize,"ocGetNames_MachO(common symbols)");
-    commonCounter = (unsigned long)commonStorage;
-
-    if (symLC) {
-        for (i = 0; i < symLC->nsyms; i++) {
-            if((nlist[i].n_type & N_TYPE) == N_UNDF
-             && (nlist[i].n_type & N_EXT)
-             && (nlist[i].n_value != 0)) {
-
-                SymbolName* nm = image + symLC->stroff + nlist[i].n_un.n_strx;
-                unsigned long sz = nlist[i].n_value;
-
-                nlist[i].n_value = commonCounter;
-
-                IF_DEBUG(linker, debugBelch("ocGetNames_MachO: inserting common symbol: %s\n", nm));
-                ghciInsertSymbolTable(oc->fileName, symhash, nm,
-                                       (void*)commonCounter, HS_BOOL_FALSE, oc);
-                oc->symbols[curSymbol] = nm;
-                curSymbol++;
-
-                commonCounter += sz;
-            }
-        }
-    }
-
-    IF_DEBUG(linker, debugBelch("ocGetNames_MachO: done\n"));
-    return 1;
-}
-
-static int
-ocResolve_MachO(ObjectCode* oc)
-{
-    char *image = (char*) oc->image;
-    struct mach_header *header = (struct mach_header*) image;
-    struct load_command *lc = (struct load_command*) (image + sizeof(struct mach_header));
-    unsigned i;
-    struct segment_command *segLC = NULL;
-    struct section *sections;
-    struct symtab_command *symLC = NULL;
-    struct dysymtab_command *dsymLC = NULL;
-    struct nlist *nlist;
-
-    IF_DEBUG(linker, debugBelch("ocResolve_MachO: start\n"));
-    for (i = 0; i < header->ncmds; i++)
-    {
-        if (lc->cmd == LC_SEGMENT || lc->cmd == LC_SEGMENT_64) {
-            segLC = (struct segment_command*) lc;
-            IF_DEBUG(linker, debugBelch("ocResolve_MachO: found a 32 or 64 bit segment load command\n"));
-        }
-        else if (lc->cmd == LC_SYMTAB) {
-            symLC = (struct symtab_command*) lc;
-            IF_DEBUG(linker, debugBelch("ocResolve_MachO: found a symbol table load command\n"));
-        }
-        else if (lc->cmd == LC_DYSYMTAB) {
-            dsymLC = (struct dysymtab_command*) lc;
-            IF_DEBUG(linker, debugBelch("ocResolve_MachO: found a dynamic symbol table load command\n"));
-        }
-
-        lc = (struct load_command *) ( ((char*)lc) + lc->cmdsize );
-    }
-
-    sections = (struct section*) (segLC+1);
-    nlist = symLC ? (struct nlist*) (image + symLC->symoff)
-                  : NULL;
-
-    if(dsymLC)
-    {
-        unsigned long *indirectSyms
-            = (unsigned long*) (image + dsymLC->indirectsymoff);
-
-        IF_DEBUG(linker, debugBelch("ocResolve_MachO: resolving dsymLC\n"));
-        for (i = 0; i < segLC->nsects; i++)
-        {
-            if(    !strcmp(sections[i].sectname,"__la_symbol_ptr")
-                || !strcmp(sections[i].sectname,"__la_sym_ptr2")
-                || !strcmp(sections[i].sectname,"__la_sym_ptr3"))
-            {
-                if(!resolveImports(oc,image,symLC,&sections[i],indirectSyms,nlist))
-                    return 0;
-            }
-            else if(!strcmp(sections[i].sectname,"__nl_symbol_ptr")
-                ||  !strcmp(sections[i].sectname,"__pointers"))
-            {
-                if(!resolveImports(oc,image,symLC,&sections[i],indirectSyms,nlist))
-                    return 0;
-            }
-            else if(!strcmp(sections[i].sectname,"__jump_table"))
-            {
-                if(!resolveImports(oc,image,symLC,&sections[i],indirectSyms,nlist))
-                    return 0;
-            }
-            else
-            {
-                IF_DEBUG(linker, debugBelch("ocResolve_MachO: unknown section\n"));
-            }
-        }
-    }
-
-    for(i=0;i<segLC->nsects;i++)
-    {
-            IF_DEBUG(linker, debugBelch("ocResolve_MachO: relocating section %d\n", i));
-
-        if (!relocateSection(oc,image,symLC,nlist,segLC->nsects,sections,&sections[i]))
-            return 0;
-    }
-
-#if defined (powerpc_HOST_ARCH)
-    ocFlushInstructionCache( oc );
-#endif
-
-    return 1;
-}
-
-static int ocRunInit_MachO ( ObjectCode *oc )
-{
-    char *image = (char*) oc->image;
-    struct mach_header *header = (struct mach_header*) image;
-    struct load_command *lc = (struct load_command*) (image + sizeof(struct mach_header));
-    struct segment_command *segLC = NULL;
-    struct section *sections;
-    uint32_t i;
-
-    for (i = 0; i < header->ncmds; i++) {
-        if (lc->cmd == LC_SEGMENT || lc->cmd == LC_SEGMENT_64) {
-            segLC = (struct segment_command*) lc;
-        }
-        lc = (struct load_command *) ( ((char*)lc) + lc->cmdsize );
-    }
-    if (!segLC) {
-        barf("ocRunInit_MachO: no segment load command");
-    }
-    sections = (struct section*) (segLC+1);
-
-    int argc, envc;
-    char **argv, **envv;
-
-    getProgArgv(&argc, &argv);
-    getProgEnvv(&envc, &envv);
-
-    for (i = 0; i < segLC->nsects; i++) {
-        // ToDo: replace this with a proper check for the S_MOD_INIT_FUNC_POINTERS
-        // flag.  We should do this elsewhere in the Mach-O linker code
-        // too.  Note that the system linker will *refuse* to honor
-        // sections which don't have this flag, so this could cause
-        // weird behavior divergence (albeit reproduceable).
-        if (0 == strcmp(sections[i].sectname,"__mod_init_func")) {
-            char *init_startC = image + sections[i].offset;
-            init_t *init = (init_t*)init_startC;
-            init_t *init_end = (init_t*)(init_startC + sections[i].size);
-            for (; init < init_end; init++) {
-                (*init)(argc, argv, envv);
-            }
-        }
-    }
-
-    freeProgEnvv(envc, envv);
-    return 1;
-}
-
-#ifdef powerpc_HOST_ARCH
-/*
- * The Mach-O object format uses leading underscores. But not everywhere.
- * There is a small number of runtime support functions defined in
- * libcc_dynamic.a whose name does not have a leading underscore.
- * As a consequence, we can't get their address from C code.
- * We have to use inline assembler just to take the address of a function.
- * Yuck.
- */
-
-extern void* symbolsWithoutUnderscore[];
-
-static void
-machoInitSymbolsWithoutUnderscore(void)
-{
-    void **p = symbolsWithoutUnderscore;
-    __asm__ volatile(".globl _symbolsWithoutUnderscore\n.data\n_symbolsWithoutUnderscore:");
-
-#undef SymI_NeedsProto
-#undef SymI_NeedsDataProto
-
-#define SymI_NeedsProto(x)  \
-    __asm__ volatile(".long " # x);
-
-#define SymI_NeedsDataProto(x) \
-    SymI_NeedsProto(x)
-
-    RTS_MACHO_NOUNDERLINE_SYMBOLS
-
-    __asm__ volatile(".text");
-
-#undef SymI_NeedsProto
-#undef SymI_NeedsDataProto
-
-#define SymI_NeedsProto(x)  \
-    ghciInsertSymbolTable("(GHCi built-in symbols)", symhash, #x, *p++, HS_BOOL_FALSE, NULL);
-
-#define SymI_NeedsDataProto(x) \
-    SymI_NeedsProto(x)
-
-    RTS_MACHO_NOUNDERLINE_SYMBOLS
-
-#undef SymI_NeedsProto
-#undef SymI_NeedsDataProto
-}
-#endif
-
-#if defined(OBJFORMAT_MACHO)
-/*
- * Figure out by how much to shift the entire Mach-O file in memory
- * when loading so that its single segment ends up 16-byte-aligned
- */
-static int
-machoGetMisalignment( FILE * f )
-{
-    struct mach_header header;
-    int misalignment;
-
-    {
-        int n = fread(&header, sizeof(header), 1, f);
-        if (n != 1) {
-            barf("machoGetMisalignment: can't read the Mach-O header");
-        }
-    }
-    fseek(f, -sizeof(header), SEEK_CUR);
-
-#if x86_64_HOST_ARCH || powerpc64_HOST_ARCH
-    if(header.magic != MH_MAGIC_64) {
-        barf("Bad magic. Expected: %08x, got: %08x.",
-             MH_MAGIC_64, header.magic);
-    }
-#else
-    if(header.magic != MH_MAGIC) {
-        barf("Bad magic. Expected: %08x, got: %08x.",
-             MH_MAGIC, header.magic);
-    }
-#endif
-
-    misalignment = (header.sizeofcmds + sizeof(header))
-                    & 0xF;
-
-    return misalignment ? (16 - misalignment) : 0;
-}
-#endif
-
-#endif