gateware.boneless: use non-transparent read port (-47 LUT, -17 DFF).

Before:
   Number of wires:                462
   Number of wire bits:            899
   Number of public wires:          44
   Number of public wire bits:     386
   Number of memories:               0
   Number of memory bits:            0
   Number of processes:              0
   Number of cells:                717
     SB_CARRY                       93
     SB_DFF                          1
     SB_DFFE                         1
     SB_DFFESR                      80
     SB_DFFSR                       36
     SB_LUT4                       505
     SB_RAM40_4K                     1

After:
   Number of wires:                416
   Number of wire bits:            868
   Number of public wires:          45
   Number of public wire bits:     402
   Number of memories:               0
   Number of memory bits:            0
   Number of processes:              0
   Number of cells:                670
     SB_CARRY                       93
     SB_DFF                          1
     SB_DFFE                         1
     SB_DFFESR                      80
     SB_DFFSR                       19
     SB_LUT4                       475
     SB_RAM40_4K                     1

Author: whitequark

software/glasgow/gateware/boneless.py

@@ -285,8 +285,8 @@ def do_finalize(self):
         self.mem = Memory(width=16, depth=len(self.mem_init), init=self.mem_init)
         self.specials += self.mem
 
-        mem_rdport = self.mem.get_port(has_re=True)
-        mem_wrport = self.mem.get_port(has_re=True, write_capable=True)
+        mem_rdport = self.mem.get_port(has_re=True, mode=READ_FIRST)
+        mem_wrport = self.mem.get_port(write_capable=True)
         self.specials += [mem_rdport, mem_wrport]
 
         if self.ext_init:
@@ -699,8 +699,8 @@ def __init__(self, has_pins=False):
             ]
 
         self.specials.mem = Memory(width=16, depth=256)
-        self.specials.mem_rdport = self.mem.get_port(has_re=True)
-        self.specials.mem_wrport = self.mem.get_port(has_re=True, write_capable=True)
+        self.specials.mem_rdport = self.mem.get_port(has_re=True, mode=READ_FIRST)
+        self.specials.mem_wrport = self.mem.get_port(write_capable=True)
         self.submodules.dut = BonelessCore(reset_addr=8,
             mem_rdport=self.mem_rdport,
             mem_wrport=self.mem_wrport,