[clang] [HLSL] Implement HLSL intialization list support (PR #123141)

[Helena Kotas via cfe-commits]

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@@ -2576,3 +2576,162 @@ void SemaHLSL::processExplicitBindingsOnDecl(VarDecl *VD) {
     }
   }
 }
+
+static bool CastInitializer(Sema &S, ASTContext &Ctx, Expr *E,
+                            llvm::SmallVectorImpl<Expr *> &List,
+                            llvm::SmallVectorImpl<QualType> &DestTypes) {
+  if (List.size() >= DestTypes.size())
+    return false;
+  InitializedEntity Entity =
+      InitializedEntity::InitializeParameter(Ctx, DestTypes[List.size()], false);
+  ExprResult Res =
+      S.PerformCopyInitialization(Entity, E->getBeginLoc(), E);
+  if (Res.isInvalid())
+    return false;
+  Expr *Init = Res.get();
+  List.push_back(Init);
+  return true;
+}
+
+static void BuildIntializerList(Sema &S, ASTContext &Ctx, Expr *E,
+                                llvm::SmallVectorImpl<Expr *> &List,
+                                llvm::SmallVectorImpl<QualType> &DestTypes,
+                                bool &ExcessInits) {
+  if (List.size() >= DestTypes.size()) {
+    ExcessInits = true;
+    return;
+  }
+
+  // If this is an initialization list, traverse the sub initializers.
+  if (auto *Init = dyn_cast<InitListExpr>(E)) {
+    for (auto *SubInit : Init->inits())
+      BuildIntializerList(S, Ctx, SubInit, List, DestTypes, ExcessInits);
+    return;
+  }
+
+  // If this is a scalar type, just enqueue the expression.
+  QualType Ty = E->getType();
+  if (Ty->isScalarType()) {
+    (void)CastInitializer(S, Ctx, E, List, DestTypes);
+    return;
+  }
+
+  if (auto *ATy = Ty->getAs<VectorType>()) {
+    uint64_t Size = ATy->getNumElements();
+
+    if (List.size() + Size > DestTypes.size()) {
+      ExcessInits = true;
+      return;
+    }
+    QualType SizeTy = Ctx.getSizeType();
+    uint64_t SizeTySize = Ctx.getTypeSize(SizeTy);
+    for (uint64_t I = 0; I < Size; ++I) {
+      auto *Idx = IntegerLiteral::Create(Ctx, llvm::APInt(SizeTySize, I),
+                                         SizeTy, SourceLocation());
+
+      ExprResult ElExpr = S.CreateBuiltinArraySubscriptExpr(
+          E, E->getBeginLoc(), Idx, E->getEndLoc());
+      if (ElExpr.isInvalid())
+        return;
+      if (!CastInitializer(S, Ctx, ElExpr.get(), List, DestTypes))
+        return;
+    }
+    return;
+  }
+
+  if (auto *VTy = dyn_cast<ConstantArrayType>(Ty.getTypePtr())) {
+    uint64_t Size = VTy->getZExtSize();
+    QualType SizeTy = Ctx.getSizeType();
+    uint64_t SizeTySize = Ctx.getTypeSize(SizeTy);
+    for (uint64_t I = 0; I < Size; ++I) {
+      auto *Idx = IntegerLiteral::Create(Ctx, llvm::APInt(SizeTySize, I),
+                                         SizeTy, SourceLocation());
+      ExprResult ElExpr = S.CreateBuiltinArraySubscriptExpr(
+          E, E->getBeginLoc(), Idx, E->getEndLoc());
+      if (ElExpr.isInvalid())
+        return;
+      BuildIntializerList(S, Ctx, ElExpr.get(), List, DestTypes, ExcessInits);
+    }
+    return;
+  }
+
+  if (auto *RTy = Ty->getAs<RecordType>()) {
+    for (auto *FD : RTy->getDecl()->fields()) {
----------------
hekota wrote:

What if the record has a base class with additional fields? I believe `fields()` iterates over the fields on this class but not base class fields.

https://github.com/llvm/llvm-project/pull/123141