LTO: Add support for multi-module bitcode files.

Differential Revision: https://reviews.llvm.org/D27313

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@289621 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/BackendUtil.cpp

@@ -753,7 +753,7 @@ static void runThinLTOBackend(const CodeGenOptions &CGOpts, Module *M,
                                     ImportList);
 
   std::vector<std::unique_ptr<llvm::MemoryBuffer>> OwnedImports;
-  MapVector<llvm::StringRef, llvm::MemoryBufferRef> ModuleMap;
+  MapVector<llvm::StringRef, llvm::BitcodeModule> ModuleMap;
 
   for (auto &I : ImportList) {
     ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> MBOrErr =
@@ -763,7 +763,34 @@ static void runThinLTOBackend(const CodeGenOptions &CGOpts, Module *M,
              << "': " << MBOrErr.getError().message() << "\n";
       return;
     }
-    ModuleMap[I.first()] = (*MBOrErr)->getMemBufferRef();
+
+    Expected<std::vector<BitcodeModule>> BMsOrErr =
+        getBitcodeModuleList(**MBOrErr);
+    if (!BMsOrErr) {
+      handleAllErrors(BMsOrErr.takeError(), [&](ErrorInfoBase &EIB) {
+        errs() << "Error loading imported file '" << I.first()
+               << "': " << EIB.message() << '\n';
+      });
+      return;
+    }
+
+    // The bitcode file may contain multiple modules, we want the one with a
+    // summary.
+    bool FoundModule = false;
+    for (BitcodeModule &BM : *BMsOrErr) {
+      Expected<bool> HasSummary = BM.hasSummary();
+      if (HasSummary && *HasSummary) {
+        ModuleMap.insert({I.first(), BM});
+        FoundModule = true;
+        break;
+      }
+    }
+    if (!FoundModule) {
+      errs() << "Error loading imported file '" << I.first()
+             << "': Could not find module summary\n";
+      return;
+    }
+
     OwnedImports.push_back(std::move(*MBOrErr));
   }
   auto AddStream = [&](size_t Task) {

test/CodeGen/thinlto_backend.ll

@@ -9,8 +9,8 @@
 ; CHECK-WARNING: error: invalid argument '-fthinlto-index={{.*}}' only allowed with '-x ir'
 
 ; Ensure we get expected error for missing index file
-; RUN: %clang -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=bad.thinlto.bc 2>&1 | FileCheck %s -check-prefix=CHECK-ERROR
-; CHECK-ERROR: Error loading index file 'bad.thinlto.bc'
+; RUN: %clang -O2 -o %t4.o -x ir %t1.o -c -fthinlto-index=bad.thinlto.bc 2>&1 | FileCheck %s -check-prefix=CHECK-ERROR1
+; CHECK-ERROR1: Error loading index file 'bad.thinlto.bc'
 
 ; Ensure f2 was imported
 ; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc
@@ -18,6 +18,11 @@
 ; CHECK-OBJ: T f1
 ; CHECK-OBJ-NOT: U f2
 
+; Ensure we get expected error for input files without summaries
+; RUN: opt -o %t2.o %s
+; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc
+; CHECK-ERROR2: Error loading imported file '{{.*}}': Could not find module summary
+
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"