[clang] [CIR] Upstream local initialization for VectorType (PR #138107)

[Amr Hesham via cfe-commits]

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@@ -1685,6 +1686,29 @@ mlir::LogicalResult CIRToLLVMStackRestoreOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMVecCreateOpLowering::matchAndRewrite(
+    cir::VecCreateOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  // Start with an 'undef' value for the vector.  Then 'insertelement' for
+  // each of the vector elements.
+  const auto vecTy = mlir::cast<cir::VectorType>(op.getType());
+  const mlir::Type llvmTy = typeConverter->convertType(vecTy);
+  const mlir::Location loc = op.getLoc();
+  mlir::Value result = rewriter.create<mlir::LLVM::PoisonOp>(loc, llvmTy);
+  assert(vecTy.getSize() == op.getElements().size() &&
+         "cir.vec.create op count doesn't match vector type elements count");
+
+  for (uint64_t i = 0; i < vecTy.getSize(); ++i) {
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AmrDeveloper wrote:

I addressed all comments except this one :D,

To use `llvm::StoreOp` we need to construct `mlir::DenseElementsAttr`, and it takes `Array<Attribute>`, but we have `Array<Value>` for Constant values. it's easy to get the attribute from them using getDefiningOp but now what is needed is to get value from non constant value for example x in `{ 1, 2, X, 3}`

https://github.com/llvm/llvm-project/pull/138107