[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

2 files changed, 47 insertions, 27 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
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index c3531a7ecac..6defe3ae7a0 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -521,7 +521,6 @@ static unsigned getEncodedUnaryOpcode(unsigned Opcode) {
   switch (Opcode) {
   default: llvm_unreachable("Unknown binary instruction!");
   case Instruction::FNeg: return bitc::UNOP_FNEG;
-  case Instruction::Freeze: return bitc::UNOP_FREEZE;
   }
 }
 
@@ -2435,17 +2434,6 @@ void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
           Record.push_back(VE.getTypeID(C->getOperand(0)->getType()));
           Record.push_back(VE.getValueID(C->getOperand(0)));
           AbbrevToUse = CONSTANTS_CE_CAST_Abbrev;
-        } else if (Instruction::isUnaryOp(CE->getOpcode())) {
-          assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
-          Code = bitc::CST_CODE_CE_UNOP;
-          Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
-          Record.push_back(VE.getValueID(C->getOperand(0)));
-          uint64_t Flags = getOptimizationFlags(CE);
-          if (Flags != 0) {
-            assert(CE->getOpcode() == Instruction::FNeg);
-            Record.push_back(Flags);
-          }
-          break;
         } else {
           assert(CE->getNumOperands() == 2 && "Unknown constant expr!");
           Code = bitc::CST_CODE_CE_BINOP;
@@ -2457,6 +2445,16 @@ void ModuleBitcodeWriter::writeConstants(unsigned FirstVal, unsigned LastVal,
             Record.push_back(Flags);
         }
         break;
+      case Instruction::FNeg: {
+        assert(CE->getNumOperands() == 1 && "Unknown constant expr!");
+        Code = bitc::CST_CODE_CE_UNOP;
+        Record.push_back(getEncodedUnaryOpcode(CE->getOpcode()));
+        Record.push_back(VE.getValueID(C->getOperand(0)));
+        uint64_t Flags = getOptimizationFlags(CE);
+        if (Flags != 0)
+          Record.push_back(Flags);
+        break;
+      }
       case Instruction::GetElementPtr: {
         Code = bitc::CST_CODE_CE_GEP;
         const auto *GO = cast<GEPOperator>(C);
@@ -2614,17 +2612,6 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
         AbbrevToUse = FUNCTION_INST_CAST_ABBREV;
       Vals.push_back(VE.getTypeID(I.getType()));
       Vals.push_back(getEncodedCastOpcode(I.getOpcode()));
-    } else if (isa<UnaryOperator>(I)) {
-      Code = bitc::FUNC_CODE_INST_UNOP;
-      if (!pushValueAndType(I.getOperand(0), InstID, Vals))
-        AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
-      Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
-      uint64_t Flags = getOptimizationFlags(&I);
-      if (Flags != 0) {
-        if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
-          AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
-        Vals.push_back(Flags);
-      }
     } else {
       assert(isa<BinaryOperator>(I) && "Unknown instruction!");
       Code = bitc::FUNC_CODE_INST_BINOP;
@@ -2640,6 +2627,19 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
       }
     }
     break;
+  case Instruction::FNeg: {
+    Code = bitc::FUNC_CODE_INST_UNOP;
+    if (!pushValueAndType(I.getOperand(0), InstID, Vals))
+      AbbrevToUse = FUNCTION_INST_UNOP_ABBREV;
+    Vals.push_back(getEncodedUnaryOpcode(I.getOpcode()));
+    uint64_t Flags = getOptimizationFlags(&I);
+    if (Flags != 0) {
+      if (AbbrevToUse == FUNCTION_INST_UNOP_ABBREV)
+        AbbrevToUse = FUNCTION_INST_UNOP_FLAGS_ABBREV;
+      Vals.push_back(Flags);
+    }
+    break;
+  }
   case Instruction::GetElementPtr: {
     Code = bitc::FUNC_CODE_INST_GEP;
     AbbrevToUse = FUNCTION_INST_GEP_ABBREV;
@@ -3034,6 +3034,10 @@ void ModuleBitcodeWriter::writeInstruction(const Instruction &I,
     pushValue(I.getOperand(0), InstID, Vals);                   // valist.
     Vals.push_back(VE.getTypeID(I.getType())); // restype.
     break;
+  case Instruction::Freeze:
+    Code = bitc::FUNC_CODE_INST_FREEZE;
+    pushValueAndType(I.getOperand(0), InstID, Vals);
+    break;
   }
 
   Stream.EmitRecord(Code, Vals, AbbrevToUse);