[IR] Redefine Freeze instruction

Summary:
This patch redefines freeze instruction from being UnaryOperator to a subclass of UnaryInstruction.

ConstantExpr freeze is removed, as discussed in the previous review.
FreezeOperator is not added because there's no ConstantExpr freeze.
`freeze i8* null` test is added to `test/Bindings/llvm-c/freeze.ll` as well, because the null pointer-related bug in `tools/llvm-c/echo.cpp` is now fixed.
InstVisitor has visitFreeze now because freeze is not unaryop anymore.

Reviewers: whitequark, deadalnix, craig.topper, jdoerfert, lebedev.ri

Reviewed By: craig.topper, lebedev.ri

Subscribers: regehr, nlopes, mehdi_amini, hiraditya, steven_wu, dexonsmith, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69932

1 files changed, 20 insertions, 4 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 92c3e1d2dd8..b99ade6a785 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1056,13 +1056,16 @@ static int getDecodedCastOpcode(unsigned Val) {
 }
 
 static int getDecodedUnaryOpcode(unsigned Val, Type *Ty) {
+  bool IsFP = Ty->isFPOrFPVectorTy();
+  // UnOps are only valid for int/fp or vector of int/fp types
+  if (!IsFP && !Ty->isIntOrIntVectorTy())
+    return -1;
+
   switch (Val) {
   default:
     return -1;
   case bitc::UNOP_FNEG:
-    return Ty->isFPOrFPVectorTy() ? Instruction::FNeg : -1;
-  case bitc::UNOP_FREEZE:
-    return Instruction::Freeze;
+    return IsFP ? Instruction::FNeg : -1;
   }
 }
 
@@ -3863,7 +3866,7 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
     case bitc::FUNC_CODE_INST_UNOP: {    // UNOP: [opval, ty, opcode]
       unsigned OpNum = 0;
       Value *LHS;
-      if (getValueTypePair(Record, OpNum, NextValueNo, LHS, &FullTy) ||
+      if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
           OpNum+1 > Record.size())
         return error("Invalid record");
 
@@ -5116,6 +5119,19 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       OperandBundles.emplace_back(BundleTags[Record[0]], std::move(Inputs));
       continue;
     }
+
+    case bitc::FUNC_CODE_INST_FREEZE: { // FREEZE: [opty,opval]
+      unsigned OpNum = 0;
+      Value *Op = nullptr;
+      if (getValueTypePair(Record, OpNum, NextValueNo, Op, &FullTy))
+        return error("Invalid record");
+      if (OpNum != Record.size())
+        return error("Invalid record");
+
+      I = new FreezeInst(Op);
+      InstructionList.push_back(I);
+      break;
+    }
     }
 
     // Add instruction to end of current BB.  If there is no current BB, reject