Add a libLTO API to query a memory buffer and check if it contains ObjC categories

The linker supports a feature to force load an object from a static
archive if it defines an Objective-C category.
This API supports this feature by looking at every section in the
module to find if a category is defined in the module.

llvm-svn: 275125

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/tools/llvm-lto/llvm-lto.cpp b/llvm/tools/llvm-lto/llvm-lto.cpp
index f3c6c62d496..84dce23aee2 100644
--- a/llvm/tools/llvm-lto/llvm-lto.cpp
+++ b/llvm/tools/llvm-lto/llvm-lto.cpp
@@ -156,6 +156,10 @@ static cl::opt<bool> RestoreGlobalsLinkage(
     "restore-linkage", cl::init(false),
     cl::desc("Restore original linkage of globals prior to CodeGen"));
 
+static cl::opt<bool> CheckHasObjC(
+    "check-for-objc", cl::init(false),
+    cl::desc("Only check if the module has objective-C defined in it"));
+
 namespace {
 struct ModuleInfo {
   std::vector<bool> CanBeHidden;
@@ -714,6 +718,21 @@ int main(int argc, char **argv) {
     return 0;
   }
 
+  if (CheckHasObjC) {
+    for (auto &Filename : InputFilenames) {
+      ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
+          MemoryBuffer::getFile(Filename);
+      error(BufferOrErr, "error loading file '" + Filename + "'");
+      auto Buffer = std::move(BufferOrErr.get());
+      LLVMContext Ctx;
+      if (llvm::isBitcodeContainingObjCCategory(*Buffer, Ctx))
+        outs() << "Bitcode " << Filename << " contains ObjC\n";
+      else
+        outs() << "Bitcode " << Filename << " does not contain ObjC\n";
+    }
+    return 0;
+  }
+
   if (ThinLTOMode.getNumOccurrences()) {
     if (ThinLTOMode.getNumOccurrences() > 1)
       report_fatal_error("You can't specify more than one -thinlto-action");