[Bitcode] Add partial support for opaque pointer auto-upgrade

Auto-upgrades that rely on the pointer element type do not work in
opaque pointer mode. The idea behind this patch is that we can
instead work with type IDs, for which we can retain the pointer
element type. For typed pointer bitcode, we will have a distinct
type ID for pointers with distinct element type, even if there will
only be a single corresponding opaque pointer type.

The disclaimer here is that this is only the first step of the change,
and there are still more getPointerElementType() calls to remove.
I expect that two more patches will be needed:
1. Track all "contained" type IDs, which will allow us to handle
function params (which are contained in the function type) and GEPs
(which may use vectors of pointers)
2. Track type IDs for values, which is e.g. necessary to handle loads.

Differential Revision: https://reviews.llvm.org/D118694

1 files changed, 58 insertions, 20 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 26eee99..624533b 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -483,7 +483,10 @@ class BitcodeReader : public BitcodeReaderBase, public GVMaterializer {
   std::vector<std::string> SectionTable;
   std::vector<std::string> GCTable;
 
-  std::vector<Type*> TypeList;
+  std::vector<Type *> TypeList;
+  /// Stores pointer element type for a given type ID. This is used during
+  /// upgrades of typed pointer IR in opaque pointer mode.
+  std::vector<Type *> ElementTypeList;
   DenseMap<Function *, FunctionType *> FunctionTypes;
   BitcodeReaderValueList ValueList;
   Optional<MetadataLoader> MDLoader;
@@ -591,6 +594,7 @@ private:
   StructType *createIdentifiedStructType(LLVMContext &Context);
 
   Type *getTypeByID(unsigned ID);
+  Type *getElementTypeByID(unsigned ID);
 
   Value *getFnValueByID(unsigned ID, Type *Ty) {
     if (Ty && Ty->isMetadataTy())
@@ -1176,6 +1180,23 @@ Type *BitcodeReader::getTypeByID(unsigned ID) {
   return TypeList[ID] = createIdentifiedStructType(Context);
 }
 
+Type *BitcodeReader::getElementTypeByID(unsigned ID) {
+  if (ID >= TypeList.size())
+    return nullptr;
+
+  Type *Ty = TypeList[ID];
+  if (!Ty->isPointerTy())
+    return nullptr;
+
+  Type *ElemTy = ElementTypeList[ID];
+  if (!ElemTy)
+    return nullptr;
+
+  assert(cast<PointerType>(Ty)->isOpaqueOrPointeeTypeMatches(ElemTy) &&
+         "Incorrect element type");
+  return ElemTy;
+}
+
 StructType *BitcodeReader::createIdentifiedStructType(LLVMContext &Context,
                                                       StringRef Name) {
   auto *Ret = StructType::create(Context, Name);
@@ -1708,6 +1729,7 @@ Error BitcodeReader::parseTypeTableBody() {
     // Read a record.
     Record.clear();
     Type *ResultTy = nullptr;
+    Type *ElemTy = nullptr;
     Expected<unsigned> MaybeRecord = Stream.readRecord(Entry.ID, Record);
     if (!MaybeRecord)
       return MaybeRecord.takeError();
@@ -1720,6 +1742,7 @@ Error BitcodeReader::parseTypeTableBody() {
       if (Record.empty())
         return error("Invalid record");
       TypeList.resize(Record[0]);
+      ElementTypeList.resize(Record[0]);
       continue;
     case bitc::TYPE_CODE_VOID:      // VOID
       ResultTy = Type::getVoidTy(Context);
@@ -1782,6 +1805,7 @@ Error BitcodeReader::parseTypeTableBody() {
       if (!ResultTy ||
           !PointerType::isValidElementType(ResultTy))
         return error("Invalid type");
+      ElemTy = ResultTy;
       ResultTy = PointerType::get(ResultTy, AddressSpace);
       break;
     }
@@ -1932,7 +1956,9 @@ Error BitcodeReader::parseTypeTableBody() {
       return error(
           "Invalid TYPE table: Only named structs can be forward referenced");
     assert(ResultTy && "Didn't read a type?");
-    TypeList[NumRecords++] = ResultTy;
+    TypeList[NumRecords] = ResultTy;
+    ElementTypeList[NumRecords] = ElemTy;
+    ++NumRecords;
   }
 }
 
@@ -2348,6 +2374,7 @@ Error BitcodeReader::parseConstants() {
 
   // Read all the records for this value table.
   Type *CurTy = Type::getInt32Ty(Context);
+  Type *CurElemTy = nullptr;
   unsigned NextCstNo = ValueList.size();
 
   struct DelayedShufTy {
@@ -2459,6 +2486,7 @@ Error BitcodeReader::parseConstants() {
       if (TypeList[Record[0]] == VoidType)
         return error("Invalid constant type");
       CurTy = TypeList[Record[0]];
+      CurElemTy = getElementTypeByID(Record[0]);
       continue;  // Skip the ValueList manipulation.
     case bitc::CST_CODE_NULL:      // NULL
       if (CurTy->isVoidTy() || CurTy->isFunctionTy() || CurTy->isLabelTy())
@@ -2831,9 +2859,10 @@ Error BitcodeReader::parseConstants() {
       for (unsigned i = 0; i != ConstStrSize; ++i)
         ConstrStr += (char)Record[3+AsmStrSize+i];
       UpgradeInlineAsmString(&AsmStr);
-      // FIXME: support upgrading in opaque pointers mode.
-      V = InlineAsm::get(cast<FunctionType>(CurTy->getPointerElementType()),
-                         AsmStr, ConstrStr, HasSideEffects, IsAlignStack);
+      if (!CurElemTy)
+        return error("Missing element type for old-style inlineasm");
+      V = InlineAsm::get(cast<FunctionType>(CurElemTy), AsmStr, ConstrStr,
+                         HasSideEffects, IsAlignStack);
       break;
     }
     // This version adds support for the asm dialect keywords (e.g.,
@@ -2857,9 +2886,10 @@ Error BitcodeReader::parseConstants() {
       for (unsigned i = 0; i != ConstStrSize; ++i)
         ConstrStr += (char)Record[3+AsmStrSize+i];
       UpgradeInlineAsmString(&AsmStr);
-      // FIXME: support upgrading in opaque pointers mode.
-      V = InlineAsm::get(cast<FunctionType>(CurTy->getPointerElementType()),
-                         AsmStr, ConstrStr, HasSideEffects, IsAlignStack,
+      if (!CurElemTy)
+        return error("Missing element type for old-style inlineasm");
+      V = InlineAsm::get(cast<FunctionType>(CurElemTy), AsmStr, ConstrStr,
+                         HasSideEffects, IsAlignStack,
                          InlineAsm::AsmDialect(AsmDialect));
       break;
     }
@@ -2888,9 +2918,10 @@ Error BitcodeReader::parseConstants() {
       for (unsigned i = 0; i != ConstStrSize; ++i)
         ConstrStr += (char)Record[OpNum + AsmStrSize + i];
       UpgradeInlineAsmString(&AsmStr);
-      // FIXME: support upgrading in opaque pointers mode.
-      V = InlineAsm::get(cast<FunctionType>(CurTy->getPointerElementType()),
-                         AsmStr, ConstrStr, HasSideEffects, IsAlignStack,
+      if (!CurElemTy)
+        return error("Missing element type for old-style inlineasm");
+      V = InlineAsm::get(cast<FunctionType>(CurElemTy), AsmStr, ConstrStr,
+                         HasSideEffects, IsAlignStack,
                          InlineAsm::AsmDialect(AsmDialect), CanThrow);
       break;
     }
@@ -3288,7 +3319,9 @@ Error BitcodeReader::parseGlobalVarRecord(ArrayRef<uint64_t> Record) {
     if (!Ty->isPointerTy())
       return error("Invalid type for value");
     AddressSpace = cast<PointerType>(Ty)->getAddressSpace();
-    Ty = Ty->getPointerElementType();
+    Ty = getElementTypeByID(Record[0]);
+    if (!Ty)
+      return error("Missing element type for old-style global");
   }
 
   uint64_t RawLinkage = Record[3];
@@ -3380,8 +3413,11 @@ Error BitcodeReader::parseFunctionRecord(ArrayRef<uint64_t> Record) {
   Type *FTy = getTypeByID(Record[0]);
   if (!FTy)
     return error("Invalid record");
-  if (auto *PTy = dyn_cast<PointerType>(FTy))
-    FTy = PTy->getPointerElementType();
+  if (isa<PointerType>(FTy)) {
+    FTy = getElementTypeByID(Record[0]);
+    if (!FTy)
+      return error("Missing element type for old-style function");
+  }
 
   if (!isa<FunctionType>(FTy))
     return error("Invalid type for value");
@@ -3536,7 +3572,8 @@ Error BitcodeReader::parseGlobalIndirectSymbolRecord(
   if (Record.size() < (3 + (unsigned)NewRecord))
     return error("Invalid record");
   unsigned OpNum = 0;
-  Type *Ty = getTypeByID(Record[OpNum++]);
+  unsigned TypeID = Record[OpNum++];
+  Type *Ty = getTypeByID(TypeID);
   if (!Ty)
     return error("Invalid record");
 
@@ -3545,8 +3582,10 @@ Error BitcodeReader::parseGlobalIndirectSymbolRecord(
     auto *PTy = dyn_cast<PointerType>(Ty);
     if (!PTy)
       return error("Invalid type for value");
-    Ty = PTy->getPointerElementType();
     AddrSpace = PTy->getAddressSpace();
+    Ty = getElementTypeByID(TypeID);
+    if (!Ty)
+      return error("Missing element type for old-style indirect symbol");
   } else {
     AddrSpace = Record[OpNum++];
   }
@@ -5005,10 +5044,9 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       const bool SwiftError = Bitfield::get<APV::SwiftError>(Rec);
       Type *Ty = getTypeByID(Record[0]);
       if (!Bitfield::get<APV::ExplicitType>(Rec)) {
-        auto *PTy = dyn_cast_or_null<PointerType>(Ty);
-        if (!PTy)
-          return error("Old-style alloca with a non-pointer type");
-        Ty = PTy->getPointerElementType();
+        Ty = getElementTypeByID(Record[0]);
+        if (!Ty)
+          return error("Missing element type for old-style alloca");
       }
       Type *OpTy = getTypeByID(Record[1]);
       Value *Size = getFnValueByID(Record[2], OpTy);