debugValue

    pub fn debugValue(self: *WipFunction, value: Value) Allocator.Error!Metadata.Optional {
        if (self.strip) return .none;
        const metadata: Metadata = metadata: switch (value.unwrap()) {
            .instruction => |instr_index| {
                const gop = try self.debug_values.getOrPut(self.builder.gpa, instr_index);
                if (!gop.found_existing) gop.key_ptr.* = instr_index;
                break :metadata .{ .index = @intCast(gop.index), .kind = .local };
            },
            .constant => |constant| try self.builder.metadataConstant(constant),
            .metadata => |metadata| metadata,
        };
        return metadata.toOptional();
    }