workaround for CoroSplit not spilling alloca?

My frontend is emitting an array (here called %error_return_trace_addresses). You can see we take the address of the first element and store it

; Function Attrs: nobuiltin noinline nounwind optnone
define internal fastcc i8* @failing(%StackTrace* nonnull, %Allocator*, i16*) unnamed_addr #3 !dbg !273 {
Entry:
%error_return_trace_addresses = alloca [1 x i64], align 8
%error_return_trace = alloca %StackTrace, align 8
%3 = alloca i8*, align 8
%4 = alloca %"[]u8", align 8
%5 = getelementptr inbounds %StackTrace, %StackTrace* %error_return_trace, i32 0, i32 0
store i64 0, i64* %5, align 8
%6 = getelementptr inbounds %StackTrace, %StackTrace* %error_return_trace, i32 0, i32 1
%7 = getelementptr inbounds %"[]usize", %"[]usize"* %6, i32 0, i32 0
%8 = getelementptr inbounds [1 x i64], [1 x i64]* %error_return_trace_addresses, i64 0, i64 0
store i64* %8, i64** %7, align 8

however CoroSplit does not spill it.

we write through the pointer, which writes to the fn stack data.

then there is a suspend point, and the data becomes corrupt.

then we read through the pointer and get corrupt data.

this is because %error_return_trace_addresses should be spilled.

is there a way for a frontend to explicitly require an alloca to be spilled? perhaps putting it as a field in the promise alloca?