IRGen: allow all kind of Builtin.zeroInitializer in statically initialized globals

Just use the same method to create the zero initializer constant as in `emitBuiltinCall`.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/Utilities/OptUtils.swift

@@ -391,8 +391,7 @@ extension Instruction {
     case let bi as BuiltinInst:
       switch bi.id {
       case .ZeroInitializer:
-        let type = bi.type.isBuiltinVector ? bi.type.builtinVectorElementType(in: parentFunction) : bi.type
-        return type.isBuiltinInteger || type.isBuiltinFloat
+        return bi.arguments.count == 0
       case .PtrToInt:
         return bi.operands[0].value is StringLiteralInst
       case .IntToPtr:

lib/IRGen/GenConstant.cpp

@@ -66,42 +66,6 @@ llvm::Constant *irgen::emitConstantInt(IRGenModule &IGM,
   return llvm::ConstantInt::get(IGM.getLLVMContext(), value);
 }
 
-llvm::Constant *irgen::emitConstantZero(IRGenModule &IGM, BuiltinInst *BI) {
-  assert(IGM.getSILModule().getBuiltinInfo(BI->getName()).ID ==
-         BuiltinValueKind::ZeroInitializer);
-
-  auto helper = [&](CanType astType) -> llvm::Constant * {
-    if (auto type = astType->getAs<BuiltinIntegerType>()) {
-      APInt zero(type->getWidth().getLeastWidth(), 0);
-      return llvm::ConstantInt::get(IGM.getLLVMContext(), zero);
-    }
-
-    if (auto type = astType->getAs<BuiltinFloatType>()) {
-      const llvm::fltSemantics *sema = nullptr;
-      switch (type->getFPKind()) {
-      case BuiltinFloatType::IEEE16: sema = &APFloat::IEEEhalf(); break;
-      case BuiltinFloatType::IEEE32: sema = &APFloat::IEEEsingle(); break;
-      case BuiltinFloatType::IEEE64: sema = &APFloat::IEEEdouble(); break;
-      case BuiltinFloatType::IEEE80: sema = &APFloat::x87DoubleExtended(); break;
-      case BuiltinFloatType::IEEE128: sema = &APFloat::IEEEquad(); break;
-      case BuiltinFloatType::PPC128: sema = &APFloat::PPCDoubleDouble(); break;
-      }
-      auto zero = APFloat::getZero(*sema);
-      return llvm::ConstantFP::get(IGM.getLLVMContext(), zero);
-    }
-
-    llvm_unreachable("SIL allowed an unknown type?");
-  };
-
-  if (auto vector = BI->getType().getAs<BuiltinVectorType>()) {
-    auto zero = helper(vector.getElementType());
-    auto count = llvm::ElementCount::getFixed(vector->getNumElements());
-    return llvm::ConstantVector::getSplat(count, zero);
-  }
-
-  return helper(BI->getType().getASTType());
-}
-
 llvm::Constant *irgen::emitConstantFP(IRGenModule &IGM, FloatLiteralInst *FLI) {
   return llvm::ConstantFP::get(IGM.getLLVMContext(), FLI->getValue());
 }
@@ -311,8 +275,15 @@ Explosion irgen::emitConstantValue(IRGenModule &IGM, SILValue operand,
   } else if (auto *BI = dyn_cast<BuiltinInst>(operand)) {
     auto args = BI->getArguments();
     switch (IGM.getSILModule().getBuiltinInfo(BI->getName()).ID) {
-      case BuiltinValueKind::ZeroInitializer:
-        return emitConstantZero(IGM, BI);
+      case BuiltinValueKind::ZeroInitializer: {
+        auto &resultTI = cast<LoadableTypeInfo>(IGM.getTypeInfo(BI->getType()));
+        auto schema = resultTI.getSchema();
+        Explosion out;
+        for (auto &elt : schema) {
+          out.add(llvm::Constant::getNullValue(elt.getScalarType()));
+        }
+        return out;
+      }
       case BuiltinValueKind::PtrToInt: {
         auto *ptr = emitConstantValue(IGM, args[0]).claimNextConstant();
         return llvm::ConstantExpr::getPtrToInt(ptr, IGM.IntPtrTy);

lib/IRGen/GenConstant.h

@@ -27,9 +27,6 @@ namespace irgen {
 /// Construct a ConstantInt from an IntegerLiteralInst.
 llvm::Constant *emitConstantInt(IRGenModule &IGM, IntegerLiteralInst *ILI);
 
-/// Construct a zero from a zero initializer BuiltinInst.
-llvm::Constant *emitConstantZero(IRGenModule &IGM, BuiltinInst *Bi);
-
 /// Construct a ConstantFP from a FloatLiteralInst.
 llvm::Constant *emitConstantFP(IRGenModule &IGM, FloatLiteralInst *FLI);