[lld-macho] handle option -headerpad_max_install_names

Differential Revision: https://reviews.llvm.org/D88064

lld/MachO/Config.h

@@ -36,6 +36,7 @@ struct Configuration {
   bool allLoad = false;
   bool forceLoadObjC = false;
   bool staticLink = false;
+  bool headerPadMaxInstallNames = false;
   uint32_t headerPad;
   llvm::StringRef installName;
   llvm::StringRef outputFile;

lld/MachO/Driver.cpp

@@ -521,6 +521,8 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
   config->installName =
       args.getLastArgValue(OPT_install_name, config->outputFile);
   config->headerPad = args::getHex(args, OPT_headerpad, /*Default=*/32);
+  config->headerPadMaxInstallNames =
+      args.hasArg(OPT_headerpad_max_install_names);
   config->outputType = args.hasArg(OPT_dylib) ? MH_DYLIB : MH_EXECUTE;
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
@@ -599,6 +601,7 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
     case OPT_L:
     case OPT_ObjC:
     case OPT_headerpad:
+    case OPT_headerpad_max_install_names:
     case OPT_install_name:
     case OPT_rpath:
     case OPT_sub_library:

lld/MachO/Options.td

@@ -689,11 +689,10 @@ def umbrella : Separate<["-"], "umbrella">,
      Group<grp_rare>;
 def headerpad : Separate<["-"], "headerpad">,
      MetaVarName<"<size>">,
-     HelpText<"Allocate hex <size> extra space for future expansion of the load commands via install_name_tool">,
+     HelpText<"Allocate hex <size> extra space for future expansion of the load commands via install_name_tool (default is 0x20)">,
      Group<grp_rare>;
 def headerpad_max_install_names : Flag<["-"], "headerpad_max_install_names">,
      HelpText<"Allocate extra space so all load-command paths can expand to MAXPATHLEN via install_name_tool">,
-     Flags<[HelpHidden]>,
      Group<grp_rare>;
 def bind_at_load : Flag<["-"], "bind_at_load">,
      HelpText<"Tell dyld to bind all symbols at load time, rather than lazily">,

lld/MachO/Writer.cpp

@@ -27,6 +27,8 @@
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Path.h"
 
+#include <algorithm>
+
 using namespace llvm;
 using namespace llvm::MachO;
 using namespace lld;
@@ -208,7 +210,9 @@ public:
 //   * LC_REEXPORT_DYLIB
 class LCDylib : public LoadCommand {
 public:
-  LCDylib(LoadCommandType type, StringRef path) : type(type), path(path) {}
+  LCDylib(LoadCommandType type, StringRef path) : type(type), path(path) {
+    instanceCount++;
+  }
 
   uint32_t getSize() const override {
     return alignTo(sizeof(dylib_command) + path.size() + 1, 8);
@@ -226,11 +230,16 @@ public:
     buf[path.size()] = '\0';
   }
 
+  static uint32_t getInstanceCount() { return instanceCount; }
+
 private:
   LoadCommandType type;
   StringRef path;
+  static uint32_t instanceCount;
 };
 
+uint32_t LCDylib::instanceCount = 0;
+
 class LCLoadDylinker : public LoadCommand {
 public:
   uint32_t getSize() const override {
@@ -366,6 +375,12 @@ void Writer::createLoadCommands() {
             make<LCDylib>(LC_REEXPORT_DYLIB, dylibFile->dylibName));
     }
   }
+
+  const uint32_t MACOS_MAXPATHLEN = 1024;
+  config->headerPad = std::max(
+      config->headerPad, (config->headerPadMaxInstallNames
+                              ? LCDylib::getInstanceCount() * MACOS_MAXPATHLEN
+                              : 0));
 }
 
 static size_t getSymbolPriority(const SymbolPriorityEntry &entry,

lld/test/MachO/headerpad.s

@@ -8,31 +8,84 @@
 ## just enforces a lower bound. We should consider implementing the same
 ## alignment behavior.
 
+################ Check default behavior
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.o
+# RUN: lld -flavor darwinnew -o %t %t.o
+# RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PADx
+#
+# PADx:      magic        {{.+}}  ncmds sizeofcmds        flags
+# PADx-NEXT: MH_MAGIC_64  {{.+}}  9     [[#%u, CMDSIZE:]] {{.*}}
+# PADx:      sectname __text
+# PADx-NEXT: segname __TEXT
+# PADx-NEXT: addr
+# PADx-NEXT: size
+# PADx-NEXT: offset [[#%u, CMDSIZE + 0x20 + 0x20]]
+
+################ Zero pad, no LCDylibs
 # RUN: lld -flavor darwinnew -o %t %t.o -headerpad 0
 # RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PAD0
-# PAD0:      magic        cputype  cpusubtype  caps    filetype ncmds sizeofcmds               flags
-# PAD0-NEXT: MH_MAGIC_64  X86_64   ALL         LIB64   EXECUTE  9     [[#%u, CMDSIZE:]] {{.*}}
+# RUN: lld -flavor darwinnew -o %t %t.o -headerpad 0 -headerpad_max_install_names
+# RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PAD0
+#
+# PAD0:      magic        {{.+}}  ncmds sizeofcmds        flags
+# PAD0-NEXT: MH_MAGIC_64  {{.+}}  9     [[#%u, CMDSIZE:]] {{.*}}
 # PAD0:      sectname __text
 # PAD0-NEXT: segname __TEXT
 # PAD0-NEXT: addr
 # PAD0-NEXT: size
-# PAD0-NEXT: offset [[#%u, CMDSIZE + 32]]
+# PAD0-NEXT: offset [[#%u, CMDSIZE + 0x20 + 0]]
 
+################ Each lexical form of a hex number, no LCDylibs
 # RUN: lld -flavor darwinnew -o %t %t.o -headerpad 11
 # RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PAD11
 # RUN: lld -flavor darwinnew -o %t %t.o -headerpad 0x11
 # RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PAD11
-# RUN: lld -flavor darwinnew -o %t %t.o -headerpad 0X11
+# RUN: lld -flavor darwinnew -o %t %t.o -headerpad 0X11 -headerpad_max_install_names
 # RUN: llvm-objdump --macho --all-headers %t | FileCheck %s --check-prefix=PAD11
-
+#
 # PAD11:      magic        {{.+}}  ncmds sizeofcmds        flags
 # PAD11-NEXT: MH_MAGIC_64  {{.+}}  9     [[#%u, CMDSIZE:]] {{.*}}
 # PAD11:      sectname __text
 # PAD11-NEXT: segname __TEXT
 # PAD11-NEXT: addr
 # PAD11-NEXT: size
-# PAD11-NEXT: offset [[#%u, CMDSIZE + 32 + 0x11]]
+# PAD11-NEXT: offset [[#%u, CMDSIZE + 0x20 + 0x11]]
+
+################ Each & all 3 kinds of LCDylib
+# RUN: echo "" | llvm-mc -filetype=obj -triple=x86_64-apple-darwin -o %T/null.o
+# RUN: lld -flavor darwinnew -o %T/libnull.dylib %T/null.o -dylib \
+# RUN:     -headerpad_max_install_names
+# RUN: llvm-objdump --macho --all-headers %T/libnull.dylib | FileCheck %s --check-prefix=PADMAX
+# RUN: lld -flavor darwinnew -o %T/libnull.dylib %T/null.o -dylib \
+# RUN:     -headerpad_max_install_names \
+# RUN:     -syslibroot %S/Inputs/MacOSX.sdk -lSystem
+# RUN: llvm-objdump --macho --all-headers %T/libnull.dylib | FileCheck %s --check-prefix=PADMAX
+# RUN: lld -flavor darwinnew -o %T/libnull.dylib %T/null.o -dylib \
+# RUN:     -headerpad_max_install_names \
+# RUN:     -syslibroot %S/Inputs/MacOSX.sdk -lSystem -sub_library libSystem
+# RUN: llvm-objdump --macho --all-headers %T/libnull.dylib | FileCheck %s --check-prefix=PADMAX
+#
+# PADMAX:      magic        {{.+}}  ncmds        sizeofcmds         flags
+# PADMAX-NEXT: MH_MAGIC_64  {{.+}}  [[#%u, N:]]  [[#%u, CMDSIZE:]]  {{.*}}
+# PADMAX:      sectname __text
+# PADMAX-NEXT: segname __TEXT
+# PADMAX-NEXT: addr
+# PADMAX-NEXT: size
+# PADMAX-NEXT: offset [[#%u, CMDSIZE + 0x20 + mul(0x400, N - 6)]]
+
+################ All 3 kinds of LCDylib swamped by a larger override
+# RUN: lld -flavor darwinnew -o %T/libnull.dylib %T/null.o -dylib \
+# RUN:     -headerpad_max_install_names -headerpad 0x1001 \
+# RUN:     -syslibroot %S/Inputs/MacOSX.sdk -lSystem -sub_library libSystem
+# RUN: llvm-objdump --macho --all-headers %T/libnull.dylib | FileCheck %s --check-prefix=PADOVR
+#
+# PADOVR:      magic        {{.+}}  ncmds        sizeofcmds         flags
+# PADOVR-NEXT: MH_MAGIC_64  {{.+}}  [[#%u, N:]]  [[#%u, CMDSIZE:]]  {{.*}}
+# PADOVR:      sectname __text
+# PADOVR-NEXT: segname __TEXT
+# PADOVR-NEXT: addr
+# PADOVR-NEXT: size
+# PADOVR-NEXT: offset [[#%u, CMDSIZE + 0x20 + 0x1001]]
 
 .globl _main
 _main: