[lld] 7e115da - [lld-macho] Make everything PIE by default

[Jez Ng via llvm-commits]

Author: Jez Ng
Date: 2021-04-29T15:11:23-04:00
New Revision: 7e115da5df47dbbbef141987845c1258f0c52874

URL: https://github.com/llvm/llvm-project/commit/7e115da5df47dbbbef141987845c1258f0c52874
DIFF: https://github.com/llvm/llvm-project/commit/7e115da5df47dbbbef141987845c1258f0c52874.diff

LOG: [lld-macho] Make everything PIE by default

Modern versions of macOS (>= 10.7) and in general all modern Mach-O
target archs want PIEs by default. ld64 defaults to PIE for iOS >= 4.3,
as well as for all versions of watchOS and simulators. Basically all the
platforms LLD is likely to target want PIE. So instead of cluttering LLD's
code with legacy version checks, I think it's simpler to just default to
PIE for everything.

Note that `-no_pie` still works, so users can still opt out of it.

Reviewed By: #lld-macho, thakis, MaskRay

Differential Revision: https://reviews.llvm.org/D101513

Added: 
    

Modified: 
    lld/MachO/Driver.cpp
    lld/MachO/Options.td
    lld/test/MachO/x86-64-reloc-unsigned.s

Removed: 
    


################################################################################
diff  --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 207a329eeff80..fe72e0a7c8d49 100644
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -697,29 +697,6 @@ static const char *getReproduceOption(InputArgList &args) {
   return getenv("LLD_REPRODUCE");
 }
 
-static bool isPie(InputArgList &args) {
-  if (config->outputType != MH_EXECUTE || args.hasArg(OPT_no_pie))
-    return false;
-  if (config->arch() == AK_arm64 || config->arch() == AK_arm64e ||
-      config->arch() == AK_arm64_32)
-    return true;
-
-  // TODO: add logic here as we support more archs. E.g. i386 should default
-  // to PIE from 10.7
-  assert(config->arch() == AK_x86_64 || config->arch() == AK_x86_64h ||
-         config->arch() == AK_arm64_32);
-
-  PlatformKind kind = config->platformInfo.target.Platform;
-  if (kind == PlatformKind::macOS &&
-      config->platformInfo.minimum >= VersionTuple(10, 6))
-    return true;
-
-  if (kind == PlatformKind::iOSSimulator || kind == PlatformKind::driverKit)
-    return true;
-
-  return args.hasArg(OPT_pie);
-}
-
 static void parseClangOption(StringRef opt, const Twine &msg) {
   std::string err;
   raw_string_ostream os(err);
@@ -1095,7 +1072,9 @@ bool macho::link(ArrayRef<const char *> argsArr, bool canExitEarly,
     createFiles(args);
 
     config->isPic = config->outputType == MH_DYLIB ||
-                    config->outputType == MH_BUNDLE || isPie(args);
+                    config->outputType == MH_BUNDLE ||
+                    (config->outputType == MH_EXECUTE &&
+                     args.hasFlag(OPT_pie, OPT_no_pie, true));
 
     // Now that all dylibs have been loaded, search for those that should be
     // re-exported.

diff  --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index e502ed4d734b7..344e8b2b4ce56 100644
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -370,10 +370,10 @@ def dylib_current_version : Separate<["-"], "dylib_current_version">,
 def grp_main : OptionGroup<"main">, HelpText<"MAIN EXECUTABLE">;
 
 def pie : Flag<["-"], "pie">,
-    HelpText<"Build a position independent executable (default for macOS 10.7 and later)">,
+    HelpText<"Build a position independent executable (default)">,
     Group<grp_main>;
 def no_pie : Flag<["-"], "no_pie">,
-    HelpText<"Do not build a position independent executable (default for macOS 10.6 and earlier)">,
+    HelpText<"Do not build a position independent executable">,
     Group<grp_main>;
 def pagezero_size : Separate<["-"], "pagezero_size">,
     MetaVarName<"<size>">,

diff  --git a/lld/test/MachO/x86-64-reloc-unsigned.s b/lld/test/MachO/x86-64-reloc-unsigned.s
index 1d2f0fbd3e437..7a157443162ca 100644
--- a/lld/test/MachO/x86-64-reloc-unsigned.s
+++ b/lld/test/MachO/x86-64-reloc-unsigned.s
@@ -7,16 +7,7 @@
 # RUN: llvm-objdump --macho --rebase %t-pie | FileCheck %s --check-prefix=PIE
 # RUN: %lld -pie -no_pie -o %t-no-pie %t.o
 # RUN: llvm-objdump --macho --rebase %t-no-pie | FileCheck %s --check-prefix=NO-PIE
-# RUN: %lld -no_pie -pie -o %t-no-pie %t.o
-# RUN: llvm-objdump --macho --rebase %t-no-pie | FileCheck %s --check-prefix=NO-PIE
-
-# RUN: %lld -platform_version macos 10.6.0 11.0 -o %t-pie %t.o
-# RUN: llvm-objdump --macho --rebase %t-pie | FileCheck %s --check-prefix=PIE
-# RUN: %lld -platform_version macos 10.5.0 11.0 -o %t-no-pie %t.o
-# RUN: llvm-objdump --macho --rebase %t-no-pie | FileCheck %s --check-prefix=NO-PIE
-# RUN: %lld -platform_version ios-simulator 11.0.0 14.2 -o %t-pie %t.o
-# RUN: llvm-objdump --macho --rebase %t-pie | FileCheck %s --check-prefix=PIE
-# RUN: %lld -platform_version driverkit 19.0 20.0 -o %t-pie %t.o
+# RUN: %lld -no_pie -pie -o %t-pie %t.o
 # RUN: llvm-objdump --macho --rebase %t-pie | FileCheck %s --check-prefix=PIE
 
 # CHECK:       Contents of section __DATA,foo: