[lld-macho] Implement -object_path_lto

This makes it possible for STABS entries to reference the debug info
contained in the LTO-compiled output.

I'm not sure how to test the file mtime within llvm-lit -- GNU and BSD
`stat` take different command-line arguments. I've omitted the check for
now.

Reviewed By: clayborg

Differential Revision: https://reviews.llvm.org/D92537

diff --git a/lld/MachO/Config.h b/lld/MachO/Config.h
index c130107..46ce02f 100644 (file)
--- a/lld/MachO/Config.h
+++ b/lld/MachO/Config.h
@@ -45,6 +45,7 @@ struct Configuration {
   uint32_t headerPad;
   llvm::StringRef installName;
   llvm::StringRef outputFile;
+  llvm::StringRef ltoObjPath;
   bool demangle = false;
   llvm::MachO::Architecture arch;
   PlatformInfo platform;

diff --git a/lld/MachO/Driver.cpp b/lld/MachO/Driver.cpp
index 72ef1b2..48e7e7e 100644 (file)
--- a/lld/MachO/Driver.cpp
+++ b/lld/MachO/Driver.cpp
@@ -703,6 +703,7 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
   config->printEachFile = args.hasArg(OPT_t);
   config->printWhyLoad = args.hasArg(OPT_why_load);
   config->outputType = getOutputType(args);
+  config->ltoObjPath = args.getLastArgValue(OPT_object_path_lto);
   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 1932cf4..f2a0c68 100644 (file)
--- a/lld/MachO/LTO.cpp
+++ b/lld/MachO/LTO.cpp
@@ -8,17 +8,21 @@
 
 #include "LTO.h"
 #include "Config.h"
+#include "Driver.h"
 #include "InputFiles.h"
 
 #include "lld/Common/ErrorHandler.h"
 #include "lld/Common/Strings.h"
 #include "lld/Common/TargetOptionsCommandFlags.h"
 #include "llvm/LTO/LTO.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace lld;
 using namespace lld::macho;
 using namespace llvm;
+using namespace llvm::sys;
 
 static lto::Config createConfig() {
   lto::Config c;
@@ -73,12 +77,26 @@ std::vector<ObjFile *> BitcodeCompiler::compile() {
       saveBuffer(buf[i], config->outputFile + Twine(i) + ".lto.o");
   }
 
-  // TODO: set modTime properly
+  if (!config->ltoObjPath.empty())
+    fs::create_directories(config->ltoObjPath);
+
   std::vector<ObjFile *> ret;
-  for (unsigned i = 0; i != maxTasks; ++i)
-    if (!buf[i].empty())
-      ret.push_back(
-          make<ObjFile>(MemoryBufferRef(buf[i], "lto.tmp"), /*modTime=*/0, ""));
+  for (unsigned i = 0; i != maxTasks; ++i) {
+    if (buf[i].empty()) {
+      continue;
+    }
+    SmallString<261> filePath("/tmp/lto.tmp");
+    uint32_t modTime = 0;
+    if (!config->ltoObjPath.empty()) {
+      filePath = config->ltoObjPath;
+      path::append(filePath, Twine(i) + "." +
+                                 getArchitectureName(config->arch) + ".lto.o");
+      saveBuffer(buf[i], filePath);
+      modTime = getModTime(filePath);
+    }
+    ret.push_back(make<ObjFile>(
+        MemoryBufferRef(buf[i], saver.save(filePath.str())), modTime, ""));
+  }
 
   return ret;
 }

diff --git a/lld/MachO/Options.td b/lld/MachO/Options.td
index b333d2b..b05bc9f 100644 (file)
--- a/lld/MachO/Options.td
+++ b/lld/MachO/Options.td
@@ -840,7 +840,6 @@ def no_objc_category_merging : Flag<["-"], "no_objc_category_merging">,
 def object_path_lto : Separate<["-"], "object_path_lto">,
      MetaVarName<"<path>">,
      HelpText<"Retain any temporary mach-o file in <path> that would otherwise be deleted during LTO">,
-     Flags<[HelpHidden]>,
      Group<grp_rare>;
 def lto_library : Separate<["-"], "lto_library">,
      MetaVarName<"<path>">,

diff --git a/lld/test/MachO/lto-object-path.ll b/lld/test/MachO/lto-object-path.ll
new file mode 100644 (file)
index 0000000..b362bf4
--- /dev/null
+++ b/lld/test/MachO/lto-object-path.ll
@@ -0,0 +1,37 @@
+; REQUIRES: x86
+
+; RUN: rm -rf %t; mkdir %t
+; RUN: llvm-as %s -o %t/test.o
+
+; RUN: %lld %t/test.o -o %t/test
+; RUN: llvm-nm -pa %t/test | FileCheck %s --check-prefixes CHECK,NOOBJPATH
+
+; RUN: %lld %t/test.o -o %t/test -object_path_lto %t/lto-temps
+; RUN: llvm-nm -pa %t/test | FileCheck %s --check-prefixes CHECK,OBJPATH -DDIR=%t/lto-temps
+
+; CHECK:          0000000000000000                - 00 0000    SO /tmp/test.cpp
+; NOOBJPATH-NEXT: 0000000000000000                - 03 0001   OSO /tmp/lto.tmp
+;; check that modTime is nonzero when `-object_path_lto` is provided
+; OBJPATH-NEXT:   {{[0-9a-f]*[1-9a-f]+[0-9a-f]*}} - 03 0001   OSO [[DIR]]/0.x86_64.lto.o
+; CHECK-NEXT:     {{[0-9a-f]+}}                   - 01 0000   FUN _main
+; CHECK-NEXT:     0000000000000001                - 00 0000   FUN
+; CHECK-NEXT:     0000000000000000                - 01 0000    SO
+; CHECK-NEXT:     {{[0-9a-f]+}}                   T _main
+
+target triple = "x86_64-apple-macosx10.15.0"
+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 @main() #0 !dbg !4 {
+  ret void
+}
+
+!llvm.module.flags = !{ !0, !1 }
+!llvm.dbg.cu = !{!2}
+
+!0 = !{i32 7, !"Dwarf Version", i32 4}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !3, emissionKind: FullDebug)
+!3 = !DIFile(filename: "test.cpp", directory: "/tmp")
+!4 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 1, type: !5, scopeLine: 1, unit: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{}