Add a module Hash in the bitcode and the combined index, implementing a kind of "build-id"

This is intended to be used for ThinLTO incremental build.

Differential Revision: http://reviews.llvm.org/D18213

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265095

1 files changed, 44 insertions, 10 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 93496fe8e6f..1840b60cc01 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5632,11 +5632,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModule() {
       }
       continue;
 
-    case BitstreamEntry::Record:
-      // Once we find the last record of interest, skip the rest.
-      if (VSTOffset > 0)
-        Stream.skipRecord(Entry.ID);
-      else {
+    case BitstreamEntry::Record: {
         Record.clear();
         auto BitCode = Stream.readRecord(Entry.ID, Record);
         switch (BitCode) {
@@ -5650,6 +5646,25 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModule() {
           SourceFileName = ValueName.c_str();
           break;
         }
+        /// MODULE_CODE_HASH: [5*i32]
+        case bitc::MODULE_CODE_HASH: {
+          if (Record.size() != 5)
+            return error("Invalid hash length " + Twine(Record.size()).str());
+          if (!TheIndex)
+            break;
+          if (TheIndex->modulePaths().empty())
+            // Does not have any summary emitted.
+            break;
+          if (TheIndex->modulePaths().size() != 1)
+            return error("Don't expect multiple modules defined?");
+          auto &Hash = TheIndex->modulePaths().begin()->second.second;
+          int Pos = 0;
+          for (auto &Val : Record) {
+            assert(!(Val >> 32) && "Unexpected high bits set");
+            Hash[Pos++] = Val;
+          }
+          break;
+        }
         /// MODULE_CODE_VSTOFFSET: [offset]
         case bitc::MODULE_CODE_VSTOFFSET:
           if (Record.size() < 1)
@@ -5761,7 +5776,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
       // module path string table entry with an empty (0) ID to take
       // ownership.
       FS->setModulePath(
-          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0));
+          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0)->first());
       static int RefListStartIndex = 4;
       int CallGraphEdgeStartIndex = RefListStartIndex + NumRefs;
       assert(Record.size() >= RefListStartIndex + NumRefs &&
@@ -5799,7 +5814,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
       std::unique_ptr<GlobalVarSummary> FS =
           llvm::make_unique<GlobalVarSummary>(getDecodedLinkage(RawLinkage));
       FS->setModulePath(
-          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0));
+          TheIndex->addModulePath(Buffer->getBufferIdentifier(), 0)->first());
       for (unsigned I = 2, E = Record.size(); I != E; ++I) {
         unsigned RefValueId = Record[I];
         uint64_t RefGUID = getGUIDFromValueId(RefValueId);
@@ -5887,6 +5902,7 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModuleStringTable() {
   SmallVector<uint64_t, 64> Record;
 
   SmallString<128> ModulePath;
+  ModulePathStringTableTy::iterator LastSeenModulePath;
   while (1) {
     BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
 
@@ -5907,14 +5923,32 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModuleStringTable() {
       break;
     case bitc::MST_CODE_ENTRY: {
       // MST_ENTRY: [modid, namechar x N]
+      uint64_t ModuleId = Record[0];
+
       if (convertToString(Record, 1, ModulePath))
         return error("Invalid record");
-      uint64_t ModuleId = Record[0];
-      StringRef ModulePathInMap = TheIndex->addModulePath(ModulePath, ModuleId);
-      ModuleIdMap[ModuleId] = ModulePathInMap;
+
+      LastSeenModulePath = TheIndex->addModulePath(ModulePath, ModuleId);
+      ModuleIdMap[ModuleId] = LastSeenModulePath->first();
+
       ModulePath.clear();
       break;
     }
+    /// MST_CODE_HASH: [5*i32]
+    case bitc::MST_CODE_HASH: {
+      if (Record.size() != 5)
+        return error("Invalid hash length " + Twine(Record.size()).str());
+      if (LastSeenModulePath == TheIndex->modulePaths().end())
+        return error("Invalid hash that does not follow a module path");
+      int Pos = 0;
+      for (auto &Val : Record) {
+        assert(!(Val >> 32) && "Unexpected high bits set");
+        LastSeenModulePath->second.second[Pos++] = Val;
+      }
+      // Reset LastSeenModulePath to avoid overriding the hash unexpectedly.
+      LastSeenModulePath = TheIndex->modulePaths().end();
+      break;
+    }
     }
   }
   llvm_unreachable("Exit infinite loop");