Using Unisim with GHDL: vital_timing and vital_primitives not found in ieee library - ghdl

Question

I'm trying to simulate a component that uses a component from the Xilinx Unisim library that came with ISE. How can I do that?
Here is what I tried. I ran into a problem I don't understand.
$ ls
DualPortMemory.vhd TestDualPortMemory.vhd Utilities.vhd
$ ghdl --clean
$ ghdl -i --work=unisim /opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/*.vhd
$ ghdl -i --work=unisim /opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/primitive/*.vhd
$ ghdl -i *.vhd
$ ghdl -m -g -Punisim --warn-unused --ieee=synopsys TestDualPortMemory
/opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/primitive/RAMB16_S9_S18.vhd:24:10:error: unit "vital_timing" not found in library "ieee"
/opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/unisim_VPKG.vhd:48:10:error: unit "vital_timing" not found in library "ieee"
/opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/unisim_VPKG.vhd:49:10:error: unit "vital_primitives" not found in library "ieee"
/opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/unisim_VPKG.vhd:66:16:error: no declaration for "vitaltablesymboltype"
/opt/Xilinx/14.7/ISE_DS/ISE/vhdl/src/unisims/unisim_VPKG.vhd:67:16:error: no declaration for "vitaltablesymboltype"
And then many many more errors.
Here is the GHDL version information:
GHDL 0.37 (Ubuntu 0.37+dfsg-1ubuntu1) [Dunoon edition]
Compiled with GNAT Version: 9.3.0
llvm code generator
Written by Tristan Gingold.
Copyright (C) 2003 - 2020 Tristan Gingold.
GHDL is free software, covered by the GNU General Public License. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.