[lld-macho] Run ObjCContractPass during LTO

Run the ObjCARCContractPass during LTO. The legacy LTO backend (under
LTO/ThinLTOCodeGenerator.cpp) already does this; this diff just adds that
behavior to the new LTO backend. Without that pass, the objc.clang.arc.use
intrinsic will get passed to the instruction selector, which doesn't know how to
handle it.

In order to test both the new and old pass managers, I've also added support for
the `--[no-]lto-legacy-pass-manager` flags.

P.S. Not sure if the ordering of the pass within the pipeline matters...

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D94547

diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
index 4f27ec2..f6e1f13 100644 (file)
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -47,6 +47,7 @@ struct Configuration {
   bool implicitDylibs = false;
   bool isPic = false;
   bool headerPadMaxInstallNames = false;
+  bool ltoNewPassManager = LLVM_ENABLE_NEW_PASS_MANAGER;
   bool printEachFile = false;
   bool printWhyLoad = false;
   bool searchDylibsFirst = false;

diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 857c999..1b337f3 100644 (file)
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -733,6 +733,9 @@ bool macho::link(ArrayRef<const char *> argsArr, bool canExitEarly,
   config->printWhyLoad = args.hasArg(OPT_why_load);
   config->outputType = getOutputType(args);
   config->ltoObjPath = args.getLastArgValue(OPT_object_path_lto);
+  config->ltoNewPassManager =
+      args.hasFlag(OPT_no_lto_legacy_pass_manager, OPT_lto_legacy_pass_manager,
+                   LLVM_ENABLE_NEW_PASS_MANAGER);
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
   config->forceLoadObjC = args.hasArg(OPT_ObjC);

diff --git a/lld/MachO/LTO.cpp b/lld/MachO/LTO.cpp
index 7554693..f48bc24 100644 (file)
--- a/lld/MachO/LTO.cpp
+++ b/lld/MachO/LTO.cpp
@@ -18,6 +18,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/ObjCARC.h"
 
 using namespace lld;
 using namespace lld::macho;
@@ -30,6 +31,10 @@ static lto::Config createConfig() {
   c.CodeModel = getCodeModelFromCMModel();
   c.CPU = getCPUStr();
   c.MAttrs = getMAttrs();
+  c.UseNewPM = config->ltoNewPassManager;
+  c.PreCodeGenPassesHook = [](legacy::PassManager &pm) {
+    pm.add(createObjCARCContractPass());
+  };
   return c;
 }
 

diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index af49788..89473ac 100644 (file)
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -29,6 +29,12 @@ def reproduce_eq: Joined<["--"], "reproduce=">,
 def version: Flag<["--"], "version">,
     HelpText<"Display the version number and exit">,
     Group<grp_lld>;
+def lto_legacy_pass_manager: Flag<["--"], "lto-legacy-pass-manager">,
+    HelpText<"Use the legacy pass manager in LLVM">,
+    Group<grp_lld>;
+def no_lto_legacy_pass_manager : Flag<["--"], "no-lto-legacy-pass-manager">,
+    HelpText<"Use the new pass manager in LLVM">,
+    Group<grp_lld>;
 
 
 // This is a complete Options.td compiled from Apple's ld(1) manpage

diff --git a/lld/test/MachO/objc-arc-contract.ll b/lld/test/MachO/objc-arc-contract.ll
new file mode 100644 (file)
index 0000000..66f30dc
--- /dev/null
+++ b/lld/test/MachO/objc-arc-contract.ll
@@ -0,0 +1,30 @@
+; REQUIRES: x86
+
+;; Verify that we run the ObjCARCContractPass during LTO. Without that, the
+;; objc.clang.arc.use intrinsic will get passed to the instruction selector,
+;; which doesn't know how to handle it.
+
+; RUN: llvm-as %s -o %t.o
+; RUN: %lld -dylib -lSystem %t.o -o %t --lto-legacy-pass-manager
+; RUN: llvm-objdump -d %t | FileCheck %s
+; RUN: %lld -dylib -lSystem %t.o -o %t --no-lto-legacy-pass-manager
+; RUN: llvm-objdump -d %t | FileCheck %s
+
+; RUN: opt -module-summary %s -o %t.o
+; RUN: %lld -dylib -lSystem %t.o -o %t --lto-legacy-pass-manager
+; RUN: llvm-objdump -d %t | FileCheck %s
+; RUN: %lld -dylib -lSystem %t.o -o %t --no-lto-legacy-pass-manager
+; RUN: llvm-objdump -d %t | FileCheck %s
+
+; CHECK:      <_foo>:
+; CHECK-NEXT: retq
+
+target triple = "x86_64-apple-darwin"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @foo(i8* %a, i8* %b) {
+  call void (...) @llvm.objc.clang.arc.use(i8* %a, i8* %b) nounwind
+  ret void
+}
+
+declare void @llvm.objc.clang.arc.use(...) nounwind

diff --git a/llvm/include/llvm/LTO/Config.h b/llvm/include/llvm/LTO/Config.h
index 1a7595d..88c1452 100644 (file)
--- a/llvm/include/llvm/LTO/Config.h
+++ b/llvm/include/llvm/LTO/Config.h
@@ -19,6 +19,7 @@
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Passes/PassBuilder.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Target/TargetOptions.h"
@@ -43,6 +44,8 @@ struct Config {
   TargetOptions Options;
   std::vector<std::string> MAttrs;
   std::vector<std::string> PassPlugins;
+  /// For adding passes that run right before codegen.
+  std::function<void(legacy::PassManager &)> PreCodeGenPassesHook;
   Optional<Reloc::Model> RelocModel = Reloc::PIC_;
   Optional<CodeModel::Model> CodeModel = None;
   CodeGenOpt::Level CGOptLevel = CodeGenOpt::Default;

diff --git a/llvm/lib/LTO/LTOBackend.cpp b/llvm/lib/LTO/LTOBackend.cpp
index effbdf6..8328224 100644 (file)
--- a/llvm/lib/LTO/LTOBackend.cpp
+++ b/llvm/lib/LTO/LTOBackend.cpp
@@ -428,6 +428,8 @@ static void codegen(const Config &Conf, TargetMachine *TM,
   legacy::PassManager CodeGenPasses;
   CodeGenPasses.add(
       createImmutableModuleSummaryIndexWrapperPass(&CombinedIndex));
+  if (Conf.PreCodeGenPassesHook)
+    Conf.PreCodeGenPassesHook(CodeGenPasses);
   if (TM->addPassesToEmitFile(CodeGenPasses, *Stream->OS,
                               DwoOut ? &DwoOut->os() : nullptr,
                               Conf.CGFileType))