[clang] Pass more flags to ld64.lld

[thakis]

Summary

• ld64.lld now completely supports -export_dynamic (D119372), so map -rdynamic to -export_dynamic like already done for ld64

• ld64.lld has been supporting -object_path_lto for well over a year (D92537), so pass it like already done for ld64

[thakis]

clang/lib/Driver/ToolChains/Darwin.cpp

242

lgrey: Do you think this should interact with 134275d994d5fb38edfeb587ba45c8f495c8bf66 in any way, or should have any other interesting side effects?

From what I understand, it tells the linker to put temporary files created for LTO in the given directory, but then the clang driver cleans up that directory when it exits (potentially after running dsymutil). But most people run dsymutil later, separately, so I think there should be no interactions there.

[lgrey]

clang/lib/Driver/ToolChains/Darwin.cpp

242

IIUC this is orthogonal to the cache's temp files. Something's actually not adding up here for me (why was it looking at the LTO cache files in the first place?), but this change shouldn't affect the cache thing.

[MaskRay]

clang/lib/Driver/ToolChains/Darwin.cpp

272

lld runs --icf=none (i.e. -no_deduplicate) by default.

clang/test/Driver/darwin-ld-dedup.c

4

If you are going to change the command line, prefer the canonical --target= to the legacy -target .

[thakis]

clang/lib/Driver/ToolChains/Darwin.cpp

272

Hm, good point. Should we pass --icf=safe for lld if !shouldLinkerNotDedup here then?

clang/test/Driver/darwin-ld-dedup.c

4

"legacy" really has no semantic meaning here other than "I like that other spelling more". It's not like we're ever going to remove -target, it's way too actively used (see e.g. D119446 :P).

It seems like a change unrelated to what this patch is doing. If we want to change it, we can do it in a separate patch.

[thakis]

undo no_deduplicate bit again for now

[thakis]

Pass -B with -fuse-ld=lld since the latter flag only has an effect if ld64.lld exists on disk, and clang/test doesn't depend on lld (and shouldn't).

Also move object_path_lto to its own file since it can run fine on non-darwin hosts.

[thakis]

lld-macho folks, any concerns with this?

[int3]

lgtm!

clang/lib/Driver/ToolChains/Darwin.cpp

272

I think our dedup pass is both a lot more effective and a lot more expensive link-time-wise than ld64's so maybe we shouldn't do it by default...

[MaskRay]

clang/lib/Driver/ToolChains/Darwin.cpp

272

FIXME: lld doesn't dedup by default.

I agree that we should not do icf by default. It can easily take more than 10% time IIRC.

[thakis]

Thanks!

clang/lib/Driver/ToolChains/Darwin.cpp

void darwin::Linker::AddLinkArgs(Compilation &C, const ArgList &Args,
   const toolchains::MachO &MachOTC = getMachOToolChain();
 
   // Newer linkers support -demangle. Pass it if supported and not disabled by
   // the user.
   if ((Version >= VersionTuple(100) || LinkerIsLLD) &&
       !Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
     CmdArgs.push_back("-demangle");
 
-  // FIXME: Pass most of the flags below that check Version if LinkerIsLLD too.
-
-  if (Args.hasArg(options::OPT_rdynamic) && Version >= VersionTuple(137))
+  if (Args.hasArg(options::OPT_rdynamic) &&
+      (Version >= VersionTuple(137) || LinkerIsLLD))
     CmdArgs.push_back("-export_dynamic");
 
   // If we are using App Extension restrictions, pass a flag to the linker
   // telling it that the compiled code has been audited.
   if (Args.hasFlag(options::OPT_fapplication_extension,
                    options::OPT_fno_application_extension, false))
     CmdArgs.push_back("-application_extension");
 
-  if (D.isUsingLTO() && Version >= VersionTuple(116) && NeedsTempPath(Inputs)) {
+  if (D.isUsingLTO() && (Version >= VersionTuple(116) || LinkerIsLLD) &&
+      NeedsTempPath(Inputs)) {
     std::string TmpPathName;
     if (D.getLTOMode() == LTOK_Full) {
       // If we are using full LTO, then automatically create a temporary file
       // path for the linker to use, so that it's lifetime will extend past a
       // possible dsymutil step.
       TmpPathName =
           D.GetTemporaryPath("cc", types::getTypeTempSuffix(types::TY_Object));
     } else if (D.getLTOMode() == LTOK_Thin)
       // If we are using thin LTO, then create a directory instead.
       TmpPathName = D.GetTemporaryDirectory("thinlto");
 
     if (!TmpPathName.empty()) {
       auto *TmpPath = C.getArgs().MakeArgString(TmpPathName);
       C.addTempFile(TmpPath);
       CmdArgs.push_back("-object_path_lto");
       CmdArgs.push_back(TmpPath);
     }
if (Version >= VersionTuple(133) && !LinkerIsLLD) {
     StringRef P = llvm::sys::path::parent_path(D.Dir);
     SmallString<128> LibLTOPath(P);
     llvm::sys::path::append(LibLTOPath, "lib");
     llvm::sys::path::append(LibLTOPath, "libLTO.dylib");
     CmdArgs.push_back("-lto_library");
     CmdArgs.push_back(C.getArgs().MakeArgString(LibLTOPath));
   }
 
-  // ld64 version 262 and above run the deduplicate pass by default.
-  if (Version >= VersionTuple(262) && shouldLinkerNotDedup(C.getJobs().empty(), Args))
+  // ld64 version 262 and above and lld run the deduplicate pass by default.
+  if ((Version >= VersionTuple(262) || LinkerIsLLD) &&
+      shouldLinkerNotDedup(C.getJobs().empty(), Args))
     CmdArgs.push_back("-no_deduplicate");
 
   // Derived from the "link" spec.
   Args.AddAllArgs(CmdArgs, options::OPT_static);
   if (!Args.hasArg(options::OPT_static))
     CmdArgs.push_back("-dynamic");
   if (Args.hasArg(options::OPT_fgnu_runtime)) {
     // FIXME: gcc replaces -lobjc in forward args with -lobjc-gnu
else
       CmdArgs.push_back("-no_pie");
   }
 
   // for embed-bitcode, use -bitcode_bundle in linker command
   if (C.getDriver().embedBitcodeEnabled()) {
     // Check if the toolchain supports bitcode build flow.
     if (MachOTC.SupportsEmbeddedBitcode()) {
       CmdArgs.push_back("-bitcode_bundle");
+      // FIXME: Pass this if LinkerIsLLD too, once it implements this flag.
       if (C.getDriver().embedBitcodeMarkerOnly() &&
           Version >= VersionTuple(278)) {
         CmdArgs.push_back("-bitcode_process_mode");
         CmdArgs.push_back("marker");
       }
     } else
       D.Diag(diag::err_drv_bitcode_unsupported_on_toolchain);
   }

clang/test/Driver/darwin-ld-dedup.c

 // REQUIRES: system-darwin
 
-// -no_deduplicate is only present from ld64 version 262 and later.
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// -no_deduplicate is only present from ld64 version 262 and later, or lld.
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=261 -O0 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
 
 // Add -no_deduplicate when either -O0 or -O1 is explicitly specified
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -O0 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld=lld %s \
+// RUN:   -mlinker-version=261 -O0 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -O1 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld=lld %s \
+// RUN:   -mlinker-version=261 -O1 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
 
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -O2 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld=lld %s \
+// RUN:   -mlinker-version=262 -O2 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -O3 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -Os 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -O4 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
 // RUN:   -mlinker-version=262 -Ofast 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
 
 // Add -no_deduplicate when no -O option is specified *and* this is a compile+link
 // (implicit -O0)
-// RUN: %clang -target x86_64-apple-darwin10 -### %s \
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld= %s \
+// RUN:   -mlinker-version=262 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 -### -fuse-ld=lld %s \
 // RUN:   -mlinker-version=262 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
 
 // Do *not* add -no_deduplicate when no -O option is specified and this is just a link
 // (since we can't imply -O0)
 // RUN: rm -f %t.o %t.bin
 // RUN: yaml2obj %S/Inputs/empty-x86_64-apple-darwin.yaml -o %t.o
-// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -mlinker-version=262 \
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld= -mlinker-version=262 \
+// RUN:   -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld=lld -mlinker-version=262 \
 // RUN:   -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -mlinker-version=262 \
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld= -mlinker-version=262 \
 // RUN:   -O0 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -mlinker-version=262 \
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld=lld -mlinker-version=262 \
+// RUN:   -O0 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld= -mlinker-version=262 \
+// RUN:   -O1 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld=lld -mlinker-version=262 \
 // RUN:   -O1 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_NODEDUP %s
-// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -mlinker-version=262 \
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld= -mlinker-version=262 \
+// RUN:   -O2 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
+// RUN: %clang -target x86_64-apple-darwin10 %t.o -### -fuse-ld=lld -mlinker-version=262 \
 // RUN:   -O2 -o %t.bin 2>&1 | FileCheck -check-prefix=LINK_DEDUP %s
 
 // LINK_NODEDUP: {{ld(.exe)?"}}
 // LINK_NODEDUP: "-no_deduplicate"
 
 // LINK_DEDUP: {{ld(.exe)?"}}
 // LINK_DEDUP-NOT: "-no_deduplicate"

clang/test/Driver/darwin-ld-lto.c

 // Also pass -lto_library even if the file doesn't exist; if it's needed at
 // link time, ld will complain instead.
 // RUN: %clang -fuse-ld= -target x86_64-apple-darwin10 -### %s \
 // RUN:   -ccc-install-dir %S/dummytestdir -mlinker-version=133 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_LTOLIB_PATH %s -input-file %t.log
 
 
 // Check that -object_lto_path is passed correctly to ld64
-// RUN: %clang -target x86_64-apple-darwin10 %s -flto=full -### 2>&1 | \
-// RUN:   FileCheck -check-prefix=FULL_LTO_OBJECT_PATH %s
+// RUN: %clang -fuse-ld= -target x86_64-apple-darwin10 %s -flto=full -### \
+// RUN:     2>&1 | FileCheck -check-prefix=FULL_LTO_OBJECT_PATH %s
+// RUN: %clang -fuse-ld=lld -target x86_64-apple-darwin10 %s -flto=full -### \
+// RUN:     2>&1 | FileCheck -check-prefix=FULL_LTO_OBJECT_PATH %s
 // FULL_LTO_OBJECT_PATH: {{ld(.exe)?"}}
 // FULL_LTO_OBJECT_PATH-SAME: "-object_path_lto"
 // FULL_LTO_OBJECT_PATH-SAME: {{cc\-[a-zA-Z0-9_]+.o}}"
-// RUN: %clang -target x86_64-apple-darwin10 %s -flto=thin -### 2>&1 | \
-// RUN:   FileCheck -check-prefix=THIN_LTO_OBJECT_PATH %s
+// RUN: %clang -fuse-ld= -target x86_64-apple-darwin10 %s -flto=thin -### \
+// RUN:     2>&1 | FileCheck -check-prefix=THIN_LTO_OBJECT_PATH %s
+// RUN: %clang -fuse-ld=lld -target x86_64-apple-darwin10 %s -flto=thin -### \
+// RUN:     2>&1 | FileCheck -check-prefix=THIN_LTO_OBJECT_PATH %s
 // THIN_LTO_OBJECT_PATH: {{ld(.exe)?"}}
 // THIN_LTO_OBJECT_PATH-SAME: "-object_path_lto"
 // THIN_LTO_OBJECT_PATH-SAME: {{thinlto\-[a-zA-Z0-9_]+}}
 
 
 // Check that we pass through -fglobal-isel flags to libLTO.
 // RUN: %clang -target arm64-apple-darwin %s -flto -fglobal-isel -### 2>&1 | \
 // RUN:   FileCheck --check-prefix=GISEL %s
 // GISEL: {{ld(.exe)?"}}
 // GISEL: "-mllvm" "-global-isel"
 // GISEL: "-mllvm" "-global-isel-abort=0"

clang/test/Driver/darwin-ld.c

 // RUN: %clang -target x86_64-apple-darwin12 -rdynamic -### %t.o \
 // RUN:   -fuse-ld= -mlinker-version=100 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_NO_EXPORT_DYNAMIC %s < %t.log
 // LINK_NO_EXPORT_DYNAMIC: {{ld(.exe)?"}}
 // LINK_NO_EXPORT_DYNAMIC-NOT: "-export_dynamic"
 
 // RUN: %clang -target x86_64-apple-darwin12 -rdynamic -### %t.o \
 // RUN:   -fuse-ld= -mlinker-version=137 2> %t.log
+// RUN: %clang -target x86_64-apple-darwin12 -rdynamic -### %t.o \
+// RUN:   -fuse-ld=lld -mlinker-version=100 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_EXPORT_DYNAMIC %s < %t.log
 // LINK_EXPORT_DYNAMIC: {{ld(.exe)?"}}
 // LINK_EXPORT_DYNAMIC: "-export_dynamic"
 
 // RUN: %clang -target x86_64h-apple-darwin -### %t.o 2> %t.log
 // RUN: FileCheck -check-prefix=LINK_X86_64H_ARCH %s < %t.log
 //
 // LINK_X86_64H_ARCH: {{ld(.exe)?"}}