[lld-macho] Avoid running LTO pipeline for no files

If no bitcode files are given as inputs but -object_path_lto is passed
we should avoid running the LTO pipeline.

This mirrors this patch from the ELF port https://github.com/llvm/llvm-project/commit/f3994e4dfa0214b2a09a0e327ba37e6b38bbcdb3

Fixes https://github.com/llvm/llvm-project/issues/61031

Differential Revision: https://reviews.llvm.org/D145273

diff --git a/lld/MachO/LTO.cpp b/lld/MachO/LTO.cpp
index 6e3d4f3..af15336 100644 (file)
--- a/lld/MachO/LTO.cpp
+++ b/lld/MachO/LTO.cpp
@@ -160,6 +160,7 @@ void BitcodeCompiler::add(BitcodeFile &f) {
     // TODO: set the other resolution configs properly
   }
   checkError(ltoObj->add(std::move(f.obj), resols));
+  hasFiles = true;
 }
 
 // If LazyObjFile has not been added to link, emit empty index files.
@@ -211,12 +212,13 @@ std::vector<ObjFile *> BitcodeCompiler::compile() {
                                files[task] = std::move(mb);
                              }));
 
-  checkError(ltoObj->run(
-      [&](size_t task, const Twine &moduleName) {
-        return std::make_unique<CachedFileStream>(
-            std::make_unique<raw_svector_ostream>(buf[task]));
-      },
-      cache));
+  if (hasFiles)
+    checkError(ltoObj->run(
+        [&](size_t task, const Twine &moduleName) {
+          return std::make_unique<CachedFileStream>(
+              std::make_unique<raw_svector_ostream>(buf[task]));
+        },
+        cache));
 
   // Emit empty index files for non-indexed files
   for (StringRef s : thinIndices) {

diff --git a/lld/MachO/LTO.h b/lld/MachO/LTO.h
index f07b1e3..86c39b1 100644 (file)
--- a/lld/MachO/LTO.h
+++ b/lld/MachO/LTO.h
@@ -39,6 +39,7 @@ private:
   std::vector<std::unique_ptr<llvm::MemoryBuffer>> files;
   std::unique_ptr<llvm::raw_fd_ostream> indexFile;
   llvm::DenseSet<StringRef> thinIndices;
+  bool hasFiles = false;
 };
 
 } // namespace lld::macho

diff --git a/lld/test/MachO/lto-object-path.ll b/lld/test/MachO/lto-object-path.ll
index d36e536..93e4e2a 100644 (file)
--- a/lld/test/MachO/lto-object-path.ll
+++ b/lld/test/MachO/lto-object-path.ll
@@ -2,12 +2,16 @@
 ; UNSUPPORTED: system-windows
 
 ; RUN: rm -rf %t; mkdir %t
+; RUN: llc -filetype=obj %s -o %t/test-obj.o
 ; RUN: opt -thinlto-bc %s -o %t/test.o
 ; RUN: opt %s -o %t/test-nonthin.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-obj.o -o %t/test-obj -object_path_lto %t/lto-temps-obj
+; RUN: llvm-nm -pa %t/test-obj | FileCheck %s --check-prefixes CHECK,NOLTOFILES -DDIR=%t
+
 ; RUN: ZERO_AR_DATE=0 %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-DIR -DDIR=%t/lto-temps
 
@@ -31,10 +35,12 @@
 ; RUN: touch %t/lto-tmp.o
 ; RUN: ZERO_AR_DATE=0 %lld %t/test-nonthin.o -o %t/test -object_path_lto %t/lto-tmp.o
 ; RUN: llvm-nm -pa %t/test | FileCheck %s --check-prefixes CHECK,OBJPATH-FILE -DFILE=%t/lto-tmp.o
+; RUN: llvm-otool -l %t/lto-tmp.o | FileCheck %s --check-prefixes=MINOS
 
 
 ; CHECK:             0000000000000000                - 00 0000    SO /tmp/test.cpp
 ; NOOBJPATH-NEXT:    0000000000000000                - 03 0001   OSO /tmp/lto.tmp
+; NOLTOFILES-NEXT:   0000000000000000                - 03 0001   OSO [[DIR]]/test-obj.o
 ;; check that modTime is nonzero when `-object_path_lto` is provided
 ; OBJPATH-DIR-NEXT:  {{[0-9a-f]*[1-9a-f]+[0-9a-f]*}} - 03 0001   OSO [[DIR]]/1.x86_64.lto.o
 ; OBJPATH-FILE-NEXT: {{[0-9a-f]*[1-9a-f]+[0-9a-f]*}} - 03 0001   OSO [[FILE]]
@@ -45,6 +51,8 @@
 ; DSYM: DW_AT_name ("test.cpp")
 ; HARDLINK: 2
 
+; MINOS: 10.15
+
 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"