[clang] [CIR] Implement global array dtor support (PR #169070)

[Erich Keane via cfe-commits]

================
@@ -693,6 +696,101 @@ void LoweringPreparePass::lowerUnaryOp(cir::UnaryOp op) {
   op.erase();
 }
 
+cir::FuncOp LoweringPreparePass::getOrCreateDtorFunc(CIRBaseBuilderTy &builder,
+                                                     cir::GlobalOp op,
+                                                     mlir::Region &dtorRegion,
+                                                     cir::CallOp &dtorCall) {
+  assert(!cir::MissingFeatures::astVarDeclInterface());
+  assert(!cir::MissingFeatures::opGlobalThreadLocal());
+
+  cir::VoidType voidTy = builder.getVoidTy();
+  auto voidPtrTy = cir::PointerType::get(voidTy);
+
+  // Look for operations in dtorBlock
+  mlir::Block &dtorBlock = dtorRegion.front();
+
+  // The first operation should be a get_global to retrieve the address
+  // of the global variable we're destroying.
+  auto opIt = dtorBlock.getOperations().begin();
+  cir::GetGlobalOp ggop = mlir::cast<cir::GetGlobalOp>(*opIt);
+
+  // The simple case is just a call to a destructor, like this:
+  //
+  //   %0 = cir.get_global %globalS : !cir.ptr<!rec_S>
----------------
erichkeane wrote:

Its a little weird that this global is required... could we make a helper for 'createDestroy' (or whatever it is?) to take the 'location' of the get and synthesize it?  It just seems odd we have a 'get_global' <this>.

Alternatively, can we assert that the global IS the current variable as a sanity assert?

https://github.com/llvm/llvm-project/pull/169070