[Clang][Bundler] Fix for a hang when unbundling fat binary

clang-offload-bundler tool may hang under certain conditions when it extracts a subset of all available device bundles from the fat binary that is handled by the BinaryFileHandler. This patch fixes this problem.

Differential Revision: https://reviews.llvm.org/D66598

llvm-svn: 370115

clang/test/Driver/clang-offload-bundler.c

@@ -221,6 +221,11 @@
 // RUN: diff %t.empty %t.res.tgt1
 // RUN: diff %t.empty %t.res.tgt2
 
+// Check that we do not have to unbundle all available bundles from the fat binary.
+// RUN: clang-offload-bundler -type=ast -targets=host-%itanium_abi_triple,openmp-x86_64-pc-linux-gnu -outputs=%t.res.ast,%t.res.tgt2 -inputs=%t.bundle3.unordered.ast -unbundle
+// RUN: diff %t.ast %t.res.ast
+// RUN: diff %t.tgt2 %t.res.tgt2
+
 //
 // Check object bundle/unbundle. The content should be bundled into an ELF
 // section (we are using a PowerPC little-endian host which uses ELF). We

clang/tools/clang-offload-bundler/ClangOffloadBundler.cpp

@@ -215,6 +215,7 @@ class BinaryFileHandler final : public FileHandler {
 
   /// Iterator for the bundle information that is being read.
   StringMap<BundleInfo>::iterator CurBundleInfo;
+  StringMap<BundleInfo>::iterator NextBundleInfo;
 
 public:
   BinaryFileHandler() : FileHandler() {}
@@ -284,19 +285,19 @@ class BinaryFileHandler final : public FileHandler {
       BundlesInfo[Triple] = BundleInfo(Size, Offset);
     }
     // Set the iterator to where we will start to read.
-    CurBundleInfo = BundlesInfo.begin();
+    CurBundleInfo = BundlesInfo.end();
+    NextBundleInfo = BundlesInfo.begin();
   }
 
   StringRef ReadBundleStart(MemoryBuffer &Input) final {
-    if (CurBundleInfo == BundlesInfo.end())
+    if (NextBundleInfo == BundlesInfo.end())
       return StringRef();
-
+    CurBundleInfo = NextBundleInfo++;
     return CurBundleInfo->first();
   }
 
   void ReadBundleEnd(MemoryBuffer &Input) final {
     assert(CurBundleInfo != BundlesInfo.end() && "Invalid reader info!");
-    ++CurBundleInfo;
   }
 
   void ReadBundle(raw_fd_ostream &OS, MemoryBuffer &Input) final {