[opaque pointer type] Bitcode support for explicit type parameter on GEP.

Like r230414, add bitcode support including backwards compatibility, for
an explicit type parameter to GEP.

At the suggestion of Duncan I tried coalescing the two older bitcodes into a
single new bitcode, though I did hit a wrinkle: I couldn't figure out how to
create an explicit abbreviation for a record with a variable number of
arguments (the indicies to the gep). This means the discriminator between
inbounds and non-inbounds gep is a full variable-length field I believe? Is my
understanding correct? Is there a way to create such an abbreviation? Should I
just use two bitcodes as before?

Reviewers: dexonsmith

Differential Revision: http://reviews.llvm.org/D7736

llvm-svn: 230415

2 files changed, 37 insertions, 7 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index c45e9645adc..92af0f8603b 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -3062,9 +3062,22 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
       InstructionList.push_back(I);
       break;
     }
-    case bitc::FUNC_CODE_INST_INBOUNDS_GEP:
-    case bitc::FUNC_CODE_INST_GEP: { // GEP: [n x operands]
+    case bitc::FUNC_CODE_INST_INBOUNDS_GEP_OLD:
+    case bitc::FUNC_CODE_INST_GEP_OLD:
+    case bitc::FUNC_CODE_INST_GEP: { // GEP: type, [n x operands]
       unsigned OpNum = 0;
+
+      Type *Ty;
+      bool InBounds;
+
+      if (BitCode == bitc::FUNC_CODE_INST_GEP) {
+        InBounds = Record[OpNum++];
+        Ty = getTypeByID(Record[OpNum++]);
+      } else {
+        InBounds = BitCode == bitc::FUNC_CODE_INST_INBOUNDS_GEP_OLD;
+        Ty = nullptr;
+      }
+
       Value *BasePtr;
       if (getValueTypePair(Record, OpNum, NextValueNo, BasePtr))
         return Error("Invalid record");
@@ -3078,8 +3091,9 @@ std::error_code BitcodeReader::ParseFunctionBody(Function *F) {
       }
 
       I = GetElementPtrInst::Create(BasePtr, GEPIdx);
+      assert(!Ty || Ty == cast<GetElementPtrInst>(I)->getSourceElementType());
       InstructionList.push_back(I);
-      if (BitCode == bitc::FUNC_CODE_INST_INBOUNDS_GEP)
+      if (InBounds)
         cast<GetElementPtrInst>(I)->setIsInBounds(true);
       break;
     }
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 16658009b18..ecb6f7c130a 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -56,7 +56,8 @@ enum {
   FUNCTION_INST_CAST_ABBREV,
   FUNCTION_INST_RET_VOID_ABBREV,
   FUNCTION_INST_RET_VAL_ABBREV,
-  FUNCTION_INST_UNREACHABLE_ABBREV
+  FUNCTION_INST_UNREACHABLE_ABBREV,
+  FUNCTION_INST_GEP_ABBREV,
 };
 
 static unsigned GetEncodedCastOpcode(unsigned Opcode) {
@@ -1675,13 +1676,16 @@ static void WriteInstruction(const Instruction &I, unsigned InstID,
     }
     break;
 
-  case Instruction::GetElementPtr:
+  case Instruction::GetElementPtr: {
     Code = bitc::FUNC_CODE_INST_GEP;
-    if (cast<GEPOperator>(&I)->isInBounds())
-      Code = bitc::FUNC_CODE_INST_INBOUNDS_GEP;
+    AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
+    auto &GEPInst = cast<GetElementPtrInst>(I);
+    Vals.push_back(GEPInst.isInBounds());
+    Vals.push_back(VE.getTypeID(GEPInst.getSourceElementType()));
     for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
       PushValueAndType(I.getOperand(i), InstID, Vals, VE);
     break;
+  }
   case Instruction::ExtractValue: {
     Code = bitc::FUNC_CODE_INST_EXTRACTVAL;
     PushValueAndType(I.getOperand(0), InstID, Vals, VE);
@@ -2287,6 +2291,18 @@ static void WriteBlockInfo(const ValueEnumerator &VE, BitstreamWriter &Stream) {
                                    Abbv) != FUNCTION_INST_UNREACHABLE_ABBREV)
       llvm_unreachable("Unexpected abbrev ordering!");
   }
+  {
+    BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+    Abbv->Add(BitCodeAbbrevOp(bitc::FUNC_CODE_INST_GEP));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 1));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, // dest ty
+                              Log2_32_Ceil(VE.getTypes().size() + 1)));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Array));
+    Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+    if (Stream.EmitBlockInfoAbbrev(bitc::FUNCTION_BLOCK_ID, Abbv) !=
+        FUNCTION_INST_GEP_ABBREV)
+      llvm_unreachable("Unexpected abbrev ordering!");
+  }
 
   Stream.ExitBlock();
 }