Due to a problem in the Intel® Quartus® Prime Pro Edition Software v21.1, you may find that the compilation time is unexpectedly long for designs containing 2D RAMs. This is because the 2D RAMs are not inferred hence the design uses a large amount of ALM resources which causes a long compilation time.
A RAM defined in VHDL as a 2D array of integers has n rows and m columns with k-bit integers. Since the integers are represented by k-bits, this adds 1 dimension and synthesis generates a 3D RAM for the 2D array of integers in VHDL.
An example VHDL code of 2D RAM that can result in this problem:
type ram_t is array (0 to 3, 0 to 3) of integer range 0 to 7;
There is no workaround to this problem.
This problem is fixed starting with the Intel® Quartus® Prime Pro Edition Software v21.3.