[clang] [CIR] Add index support for global_view (PR #153254)

[Bruno Cardoso Lopes via cfe-commits]

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@@ -66,6 +66,62 @@ clang::CIRGen::CIRGenBuilderTy::getConstFP(mlir::Location loc, mlir::Type t,
   return create<cir::ConstantOp>(loc, cir::FPAttr::get(t, fpVal));
 }
 
+void CIRGenBuilderTy::computeGlobalViewIndicesFromFlatOffset(
+    int64_t offset, mlir::Type ty, cir::CIRDataLayout layout,
+    llvm::SmallVectorImpl<int64_t> &indices) {
+  if (!offset)
+    return;
+
+  mlir::Type subType;
+
+  auto getIndexAndNewOffset =
+      [](int64_t offset, int64_t eltSize) -> std::pair<int64_t, int64_t> {
+    int64_t divRet = offset / eltSize;
+    if (divRet < 0)
+      divRet -= 1; // make sure offset is positive
+    int64_t modRet = offset - (divRet * eltSize);
+    return {divRet, modRet};
+  };
+
+  if (auto arrayTy = mlir::dyn_cast<cir::ArrayType>(ty)) {
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bcardosolopes wrote:

Should we use `TypeSwitch` here and it's result is directly into `subType`?

https://github.com/llvm/llvm-project/pull/153254