Functional tests now find a feasible period instead of using a heuristic. Bug found, trimming pbitcell netlists causes bit flips.

compiler/characterizer/functional.py

@@ -10,7 +10,7 @@ import utils
 from globals import OPTS
 
 from .simulation import simulation
-
+from .delay import delay
 
 class functional(simulation):
     """
@@ -27,6 +27,7 @@ class functional(simulation):
 
         self.set_corner(corner)
         self.set_spice_constants()
+        self.set_feasible_period(sram, spfile, corner)
         self.set_stimulus_variables()
         self.create_signal_names()
         
@@ -36,13 +37,25 @@ class functional(simulation):
         self.write_check = []
         self.read_check = []
     
-    def set_spice_constants(self):
-        """Spice constants for functional test"""
-        simulation.set_spice_constants(self)
-        #Heuristic increase for functional period. Base feasible period typically does not pass the functional test
-        #for column mux or srams of this size. Increase the feasible period by 20% for this case.
-        if self.sram.words_per_row >= 4 or self.sram.num_cols*self.sram.num_rows >= 1024:
-            self.period = self.period*1.2
+    def set_feasible_period(self, sram, spfile, corner):
+        """Creates a delay simulation to determine a feasible period for the functional tests to run.
+           Only determines the feasible period for a single port and assumes that for all ports for performance.
+        """
+        OPTS.trim_netlist = False #This has to be false or the write port will flip a bit in the trimmed netlist.
+        debug.info(1, "Determining feasible period using untrimmed netlist for functional test.")
+        delay_sim = delay(sram, spfile, corner)
+        delay_sim.set_load_slew(self.load,self.slew)
+        delay_sim.set_probe(probe_address="1"*self.addr_size, probe_data=(self.sram.word_size-1))
+        delay_sim.find_feasible_period_one_port(self.read_ports[0]) #Finds feasible and sets internal period
+        self.period = delay_sim.period #copy internal period of delay object here
+    
+    # def set_spice_constants(self):
+        # """Spice constants for functional test"""
+        # simulation.set_spice_constants(self)
+        # #Heuristic increase for functional period. Base feasible period typically does not pass the functional test
+        # #for column mux or srams of this size. Increase the feasible period by 20% for this case.
+        # if self.sram.words_per_row >= 4 or self.sram.num_cols*self.sram.num_rows >= 1024:
+            # self.period = self.period*1.2
     
     def run(self):
         # Generate a random sequence of reads and writes