[clang] [CLANG] Full support of complex multiplication and division. (PR #81514)

[Joshua Cranmer via cfe-commits]

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@@ -283,9 +283,46 @@ class ComplexExprEmitter
   ComplexPairTy EmitComplexBinOpLibCall(StringRef LibCallName,
                                         const BinOpInfo &Op);
 
-  QualType getPromotionType(QualType Ty) {
+  QualType HigherPrecisionTypeForComplexArithmetic(QualType ElementType,
+                                                   bool IsDivOpCode) {
+    const TargetInfo &TI = CGF.getContext().getTargetInfo();
+    const LangOptions Opts = CGF.getLangOpts();
+    if (const auto *BT = dyn_cast<BuiltinType>(ElementType)) {
+      switch (BT->getKind()) {
+      case BuiltinType::Kind::Float16: {
+        if (TI.hasFloat16Type() && !TI.hasLegalHalfType())
+          return CGF.getContext().getComplexType(CGF.getContext().FloatTy);
+        break;
+      }
+      case BuiltinType::Kind::BFloat16: {
+        if (TI.hasBFloat16Type() && !TI.hasFullBFloat16Type())
+          return CGF.getContext().getComplexType(CGF.getContext().FloatTy);
+        break;
+      }
+      case BuiltinType::Kind::Float:
+        return CGF.getContext().getComplexType(CGF.getContext().DoubleTy);
+        break;
+      case BuiltinType::Kind::Double: {
+        if (TI.hasLongDoubleType())
+          return CGF.getContext().getComplexType(CGF.getContext().LongDoubleTy);
+        return CGF.getContext().getComplexType(CGF.getContext().DoubleTy);
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jcranmer-intel wrote:

I'm not sure it's a good idea to return a specific type here if it's not known to actually be higher precision? `long double` isn't guaranteed to be a different LLVM type from `double`...

https://github.com/llvm/llvm-project/pull/81514