Fix PR25101 - Handle anonymous functions without VST entries

Summary:
The change to use the VST function entries for lazy deserialization did
not handle the case of anonymous functions without aliases. In that case
we must fall back to scanning the function blocks as there is no VST
entry.

Reviewers: dexonsmith, joker.eph, davidxl

Subscribers: tstellarAMD, llvm-commits

Differential Revision: http://reviews.llvm.org/D13596

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249947 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index ce6790be71373b23133d5d6d135a14cc2747dbc5..fb853b59844b60aed7bf3ea48b29dbb875faa088 100644 (file)
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -146,7 +146,10 @@ class BitcodeReader : public GVMaterializer {
   std::unique_ptr<MemoryBuffer> Buffer;
   std::unique_ptr<BitstreamReader> StreamFile;
   BitstreamCursor Stream;
   std::unique_ptr<MemoryBuffer> Buffer;
   std::unique_ptr<BitstreamReader> StreamFile;
   BitstreamCursor Stream;

+  // Next offset to start scanning for lazy parsing of function bodies.

   uint64_t NextUnreadBit = 0;
   uint64_t NextUnreadBit = 0;

+  // Last function offset found in the VST.
+  uint64_t LastFunctionBlockBit = 0;

   bool SeenValueSymbolTable = false;
   unsigned VSTOffset = 0;
 
   bool SeenValueSymbolTable = false;
   unsigned VSTOffset = 0;
 


@@ -368,7 +371,8 @@ private:
   /// a corresponding error code.
   std::error_code parseAlignmentValue(uint64_t Exponent, unsigned &Alignment);
   std::error_code parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);
   /// a corresponding error code.
   std::error_code parseAlignmentValue(uint64_t Exponent, unsigned &Alignment);
   std::error_code parseAttrKind(uint64_t Code, Attribute::AttrKind *Kind);

-  std::error_code parseModule(bool Resume, bool ShouldLazyLoadMetadata = false);
+  std::error_code parseModule(uint64_t ResumeBit,
+                              bool ShouldLazyLoadMetadata = false);

   std::error_code parseAttributeBlock();
   std::error_code parseAttributeGroupBlock();
   std::error_code parseTypeTable();
   std::error_code parseAttributeBlock();
   std::error_code parseAttributeGroupBlock();
   std::error_code parseTypeTable();


@@ -379,6 +383,7 @@ private:
                                unsigned NameIndex, Triple &TT);
   std::error_code parseValueSymbolTable(unsigned Offset = 0);
   std::error_code parseConstants();
                                unsigned NameIndex, Triple &TT);
   std::error_code parseValueSymbolTable(unsigned Offset = 0);
   std::error_code parseConstants();

+  std::error_code rememberAndSkipFunctionBodies();

   std::error_code rememberAndSkipFunctionBody();
   /// Save the positions of the Metadata blocks and skip parsing the blocks.
   std::error_code rememberAndSkipMetadata();
   std::error_code rememberAndSkipFunctionBody();
   /// Save the positions of the Metadata blocks and skip parsing the blocks.
   std::error_code rememberAndSkipMetadata();


@@ -1836,11 +1841,11 @@ std::error_code BitcodeReader::parseValueSymbolTable(unsigned Offset) {
       assert(F);
       uint64_t FuncBitOffset = FuncWordOffset * 32;
       DeferredFunctionInfo[F] = FuncBitOffset + FuncBitcodeOffsetDelta;
       assert(F);
       uint64_t FuncBitOffset = FuncWordOffset * 32;
       DeferredFunctionInfo[F] = FuncBitOffset + FuncBitcodeOffsetDelta;

-      // Set the NextUnreadBit to point to the last function block.
+      // Set the LastFunctionBlockBit to point to the last function block.

       // Later when parsing is resumed after function materialization,
       // we can simply skip that last function block.
       // Later when parsing is resumed after function materialization,
       // we can simply skip that last function block.

-      if (FuncBitOffset > NextUnreadBit)
-        NextUnreadBit = FuncBitOffset;
+      if (FuncBitOffset > LastFunctionBlockBit)
+        LastFunctionBlockBit = FuncBitOffset;

       break;
     }
     case bitc::VST_CODE_BBENTRY: {
       break;
     }
     case bitc::VST_CODE_BBENTRY: {


@@ -2987,6 +2992,9 @@ std::error_code BitcodeReader::rememberAndSkipFunctionBody() {
 
   // Save the current stream state.
   uint64_t CurBit = Stream.GetCurrentBitNo();
 
   // Save the current stream state.
   uint64_t CurBit = Stream.GetCurrentBitNo();

+  assert(
+      (DeferredFunctionInfo[Fn] == 0 || DeferredFunctionInfo[Fn] == CurBit) &&
+      "Mismatch between VST and scanned function offsets");

   DeferredFunctionInfo[Fn] = CurBit;
 
   // Skip over the function block for now.
   DeferredFunctionInfo[Fn] = CurBit;
 
   // Skip over the function block for now.


@@ -3019,10 +3027,44 @@ std::error_code BitcodeReader::globalCleanup() {
   return std::error_code();
 }
 
   return std::error_code();
 }
 

-std::error_code BitcodeReader::parseModule(bool Resume,
+/// Support for lazy parsing of function bodies. This is required if we
+/// either have an old bitcode file without a VST forward declaration record,
+/// or if we have an anonymous function being materialized, since anonymous
+/// functions do not have a name and are therefore not in the VST.
+std::error_code BitcodeReader::rememberAndSkipFunctionBodies() {
+  Stream.JumpToBit(NextUnreadBit);
+
+  if (Stream.AtEndOfStream()) return error("Could not find function in stream");
+
+  assert(SeenFirstFunctionBody);
+  // An old bitcode file with the symbol table at the end would have
+  // finished the parse greedily.
+  assert(SeenValueSymbolTable);
+
+  SmallVector<uint64_t, 64> Record;
+
+  while (1) {
+    BitstreamEntry Entry = Stream.advance();
+    switch (Entry.Kind) {
+      default:
+        return error("Expect SubBlock");
+      case BitstreamEntry::SubBlock:
+        switch (Entry.ID) {
+          default:
+            return error("Expect function block");
+          case bitc::FUNCTION_BLOCK_ID:
+            if (std::error_code EC = rememberAndSkipFunctionBody()) return EC;
+            NextUnreadBit = Stream.GetCurrentBitNo();
+            return std::error_code();
+        }
+    }
+  }
+}
+
+std::error_code BitcodeReader::parseModule(uint64_t ResumeBit,

                                            bool ShouldLazyLoadMetadata) {
                                            bool ShouldLazyLoadMetadata) {

-  if (Resume)
-    Stream.JumpToBit(NextUnreadBit);
+  if (ResumeBit)
+    Stream.JumpToBit(ResumeBit);

   else if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
     return error("Invalid record");
 
   else if (Stream.EnterSubBlock(bitc::MODULE_BLOCK_ID))
     return error("Invalid record");
 


@@ -3116,14 +3158,17 @@ std::error_code BitcodeReader::parseModule(bool Resume,
                     BitcodeReader::parseValueSymbolTable(VSTOffset))
               return EC;
             SeenValueSymbolTable = true;
                     BitcodeReader::parseValueSymbolTable(VSTOffset))
               return EC;
             SeenValueSymbolTable = true;

-            return std::error_code();
+            // Fall through so that we record the NextUnreadBit below.
+            // This is necessary in case we have an anonymous function that
+            // is later materialized. Since it will not have a VST entry we
+            // need to fall back to the lazy parse to find its offset.

           } else {
             // If we have a VST forward declaration record, but have already
             // parsed the VST (just above, when the first function body was
             // encountered here), then we are resuming the parse after
           } else {
             // If we have a VST forward declaration record, but have already
             // parsed the VST (just above, when the first function body was
             // encountered here), then we are resuming the parse after

-            // materializing functions. The NextUnreadBit points to the start
-            // of the last function block recorded in the VST (set when
-            // parsing the VST function entries). Skip it.
+            // materializing functions. The ResumeBit points to the
+            // start of the last function block recorded in the
+            // DeferredFunctionInfo map. Skip it.

             if (Stream.SkipBlock())
               return error("Invalid record");
             continue;
             if (Stream.SkipBlock())
               return error("Invalid record");
             continue;


@@ -3131,10 +3176,12 @@ std::error_code BitcodeReader::parseModule(bool Resume,
         }
 
         // Support older bitcode files that did not have the function
         }
 
         // Support older bitcode files that did not have the function

-        // index in the VST, nor a VST forward declaration record.
+        // index in the VST, nor a VST forward declaration record, as
+        // well as anonymous functions that do not have VST entries.

         // Build the DeferredFunctionInfo vector on the fly.
         if (std::error_code EC = rememberAndSkipFunctionBody())
           return EC;
         // Build the DeferredFunctionInfo vector on the fly.
         if (std::error_code EC = rememberAndSkipFunctionBody())
           return EC;

+

         // Suspend parsing when we reach the function bodies. Subsequent
         // materialization calls will resume it when necessary. If the bitcode
         // file is old, the symbol table will be at the end instead and will not
         // Suspend parsing when we reach the function bodies. Subsequent
         // materialization calls will resume it when necessary. If the bitcode
         // file is old, the symbol table will be at the end instead and will not


@@ -3506,7 +3553,7 @@ BitcodeReader::parseBitcodeInto(std::unique_ptr<DataStreamer> Streamer,
       return error("Malformed block");
 
     if (Entry.ID == bitc::MODULE_BLOCK_ID)
       return error("Malformed block");
 
     if (Entry.ID == bitc::MODULE_BLOCK_ID)

-      return parseModule(false, ShouldLazyLoadMetadata);
+      return parseModule(0, ShouldLazyLoadMetadata);

 
     if (Stream.SkipBlock())
       return error("Invalid record");
 
     if (Stream.SkipBlock())
       return error("Invalid record");


@@ -4959,16 +5006,13 @@ std::error_code BitcodeReader::findFunctionInStream(
     DenseMap<Function *, uint64_t>::iterator DeferredFunctionInfoIterator) {
   while (DeferredFunctionInfoIterator->second == 0) {
     // This is the fallback handling for the old format bitcode that
     DenseMap<Function *, uint64_t>::iterator DeferredFunctionInfoIterator) {
   while (DeferredFunctionInfoIterator->second == 0) {
     // This is the fallback handling for the old format bitcode that

-    // didn't contain the function index in the VST. Assert if we end up
-    // here for the new format (which is the only time the VSTOffset would
-    // be non-zero).
-    assert(VSTOffset == 0);
-    if (Stream.AtEndOfStream())
-      return error("Could not find function in stream");
-    // ParseModule will parse the next body in the stream and set its
-    // position in the DeferredFunctionInfo map.
-    if (std::error_code EC = parseModule(true))
-      return EC;
+    // didn't contain the function index in the VST, or when we have
+    // an anonymous function which would not have a VST entry.
+    // Assert that we have one of those two cases.
+    assert(VSTOffset == 0 || !F->hasName());
+    // Parse the next body in the stream and set its position in the
+    // DeferredFunctionInfo map.
+    if (std::error_code EC = rememberAndSkipFunctionBodies()) return EC;

   }
   return std::error_code();
 }
   }
   return std::error_code();
 }


@@ -5064,11 +5108,12 @@ std::error_code BitcodeReader::materializeModule(Module *M) {
     if (std::error_code EC = materialize(F))
       return EC;
   }
     if (std::error_code EC = materialize(F))
       return EC;
   }

-  // At this point, if there are any function bodies, the current bit is
-  // pointing to the END_BLOCK record after them. Now make sure the rest
-  // of the bits in the module have been read.
-  if (NextUnreadBit)
-    parseModule(true);
+  // At this point, if there are any function bodies, parse the rest of
+  // the bits in the module past the last function block we have recorded
+  // through either lazy scanning or the VST.
+  if (LastFunctionBlockBit || NextUnreadBit)
+    parseModule(LastFunctionBlockBit > NextUnreadBit ? LastFunctionBlockBit
+                                                     : NextUnreadBit);

 
   // Check that all block address forward references got resolved (as we
   // promised above).
 
   // Check that all block address forward references got resolved (as we
   // promised above).

diff --git a/test/Bitcode/anon-functions.ll b/test/Bitcode/anon-functions.ll
new file mode 100644 (file)
index 0000000..b68cc8e
--- /dev/null
+++ b/test/Bitcode/anon-functions.ll
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+; PR25101
+
+; CHECK: define void @0()
+define void @0() {
+  ret void
+}
+
+; CHECK: define void @f()
+define void @f() {
+  ret void
+}
+
+; CHECK: define void @1()
+define void @1() {
+  ret void
+}
+