[CGData] LLD for MachO

lld/MachO/Config.h

@@ -207,6 +207,7 @@ struct Configuration {
   std::vector<SectionAlign> sectionAlignments;
   std::vector<SegmentProtection> segmentProtections;
   bool ltoDebugPassManager = false;
+  llvm::StringRef codegenDataGeneratePath;
   bool csProfileGenerate = false;
   llvm::StringRef csProfilePath;
   bool pgoWarnMismatch;

lld/MachO/Driver.cpp

@@ -36,6 +36,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/BinaryFormat/MachO.h"
 #include "llvm/BinaryFormat/Magic.h"
+#include "llvm/CodeGenData/CodeGenDataWriter.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/LTO/LTO.h"
 #include "llvm/Object/Archive.h"
@@ -1250,6 +1251,38 @@ static void gatherInputSections() {
   }
 }
 
+static void codegenDataGenerate() {
+  TimeTraceScope timeScope("Generating codegen data");
+
+  OutlinedHashTreeRecord globalOutlineRecord;
+  for (ConcatInputSection *isec : inputSections) {
+    if (isec->getSegName() == segment_names::data &&
+        isec->getName() == section_names::outlinedHashTree) {
+      // Read outlined hash tree from each section
+      OutlinedHashTreeRecord localOutlineRecord;
+      auto *data = isec->data.data();
+      localOutlineRecord.deserialize(data);
+
+      // Merge it to the global hash tree.
+      globalOutlineRecord.merge(localOutlineRecord);
+    }
+  }
+
+  CodeGenDataWriter Writer;
+  if (!globalOutlineRecord.empty())
+    Writer.addRecord(globalOutlineRecord);
+
+  std::error_code EC;
+  auto fileName = config->codegenDataGeneratePath;
+  assert(!fileName.empty());
+  raw_fd_ostream Output(fileName, EC, sys::fs::OF_None);
+  if (EC)
+    error("fail to create raw_fd_ostream");
+
+  if (auto E = Writer.write(Output))
+    error("fail to write CGData");
+}
+
 static void foldIdenticalLiterals() {
   TimeTraceScope timeScope("Fold identical literals");
   // We always create a cStringSection, regardless of whether dedupLiterals is
@@ -1665,6 +1698,8 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
     config->ignoreAutoLinkOptions.insert(arg->getValue());
   config->strictAutoLink = args.hasArg(OPT_strict_auto_link);
   config->ltoDebugPassManager = args.hasArg(OPT_lto_debug_pass_manager);
+  config->codegenDataGeneratePath =
+      args.getLastArgValue(OPT_codegen_data_generate_path);
   config->csProfileGenerate = args.hasArg(OPT_cs_profile_generate);
   config->csProfilePath = args.getLastArgValue(OPT_cs_profile_path);
   config->pgoWarnMismatch =
@@ -1959,6 +1994,10 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
     }
 
     gatherInputSections();
+
+    if (!config->codegenDataGeneratePath.empty())
+      codegenDataGenerate();
+
     if (config->callGraphProfileSort)
       priorityBuilder.extractCallGraphProfile();
 

lld/MachO/InputSection.h

@@ -353,6 +353,7 @@ constexpr const char objcMethname[] = "__objc_methname";
 constexpr const char objcNonLazyCatList[] = "__objc_nlcatlist";
 constexpr const char objcNonLazyClassList[] = "__objc_nlclslist";
 constexpr const char objcProtoList[] = "__objc_protolist";
+constexpr const char outlinedHashTree[] = "__llvm_outline";
 constexpr const char pageZero[] = "__pagezero";
 constexpr const char pointers[] = "__pointers";
 constexpr const char rebase[] = "__rebase";

lld/MachO/Options.td

@@ -137,6 +137,8 @@ def no_objc_category_merging : Flag<["-"], "no_objc_category_merging">,
     Group<grp_lld>;
 def lto_debug_pass_manager: Flag<["--"], "lto-debug-pass-manager">,
     HelpText<"Debug new pass manager">, Group<grp_lld>;
+def codegen_data_generate_path : Joined<["--"], "codegen-data-generate-path=">,
+    HelpText<"Codegen data file path">, Group<grp_lld>;
 def cs_profile_generate: Flag<["--"], "cs-profile-generate">,
     HelpText<"Perform context sensitive PGO instrumentation">, Group<grp_lld>;
 def cs_profile_path: Joined<["--"], "cs-profile-path=">,

lld/test/MachO/cgdata-generate.s

@@ -0,0 +1,83 @@
+# REQUIRES: aarch64
+
+# RUN: rm -rf %t; split-file %s %t
+
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-1.s -o %t/merge-1.o
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/merge-2.s -o %t/merge-2.o
+# RUN: llvm-mc -filetype obj -triple arm64-apple-darwin %t/main.s -o %t/main.o
+
+# This checks if the codegen data from the linker is identical to the merged codegen data
+# from each object file, which is obtained using the llvm-cgdata tool.
+# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out \
+# RUN: %t/merge-1.o %t/merge-2.o %t/main.o --codegen-data-generate-path=%t/out-cgdata
+# RUN: llvm-cgdata merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata
+# RUN: diff %t/out-cgdata %t/merge-cgdata
+
+# Merge order doesn't matter. `main.o` is dropped due to missing __llvm_outline.
+# RUN: llvm-cgdata merge %t/merge-2.o %t/merge-1.o -o %t/merge-cgdata-shuffle
+# RUN: diff %t/out-cgdata %t/merge-cgdata-shuffle
+
+# We can also generate the merged codegen data from the executable that is not dead-stripped.
+# RUN: llvm-objdump -h %t/out| FileCheck %s
+CHECK: __llvm_outline
+# RUN: llvm-cgdata merge %t/out -o %t/merge-cgdata-exe
+# RUN: diff %t/merge-cgdata-exe %t/merge-cgdata
+
+# Dead-strip will remove __llvm_outline sections from the final executable.
+# But the codeden data is still correctly produced from the linker.
+# RUN: %no-arg-lld -dylib -arch arm64 -platform_version ios 14.0 15.0 -o %t/out-strip \
+# RUN: %t/merge-1.o %t/merge-2.o %t/main.o -dead_strip --codegen-data-generate-path=%t/out-cgdata-strip
+# RUN: llvm-cgdata merge %t/merge-1.o %t/merge-2.o %t/main.o -o %t/merge-cgdata-strip
+# RUN: diff %t/out-cgdata-strip %t/merge-cgdata-strip
+# RUN: diff %t/out-cgdata-strip %t/merge-cgdata
+
+# Ensure no __llvm_outline section remains in the executable.
+# RUN: llvm-objdump -h %t/out-strip | FileCheck %s --check-prefix=STRIP
+STRIP-NOT: __llvm_outline
+
+#--- merge-1.s
+# The .data is encoded in a binary form based on the following yaml form. See serialize() in OutlinedHashTreeRecord.cpp
+#---
+#0:
+#  Hash:            0x0
+#  Terminals:       0
+#  SuccessorIds:    [ 1 ]
+#1:
+#  Hash:            0x1
+#  Terminals:       0
+#  SuccessorIds:    [ 2 ]
+#2:
+#  Hash:            0x2
+#  Terminals:       4
+#  SuccessorIds:    [  ]
+#...
+.section __DATA,__llvm_outline
+_data:
+.byte 0x03,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x04,0x00,0x00,0x00,0x00,0x00,0x00,0x00
+
+#--- merge-2.s
+# The .data is encoded in a binary form based on the following yaml form. See serialize() in OutlinedHashTreeRecord.cpp
+#---
+#0:
+#  Hash:            0x0
+#  Terminals:       0
+#  SuccessorIds:    [ 1 ]
+#1:
+#  Hash:            0x1
+#  Terminals:       0
+#  SuccessorIds:    [ 2 ]
+#2:
+#  Hash:            0x3
+#  Terminals:       5
+#  SuccessorIds:    [  ]
+#...
+.section __DATA,__llvm_outline
+_data:
+.byte 0x03,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x02,0x00,0x00,0x00,0x03,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x05,0x00,0x00,0x00,0x00,0x00,0x00,0x00
+
+#--- main.s
+.globl _main
+
+.text
+_main:
+  ret