fhdl: pad support in fragments

migen/fhdl/structure.py

@@ -194,15 +194,20 @@ class Instance:
 		return id(self)
 
 class Fragment:
-	def __init__(self, comb=StatementList(), sync=StatementList(), instances=[]):
+	def __init__(self, comb=StatementList(), sync=StatementList(), instances=[], pads=set()):
 		self.comb = _sl(comb)
 		self.sync = _sl(sync)
 		self.instances = instances
+		self.pads = pads
 	
 	def __add__(self, other):
-		return Fragment(self.comb.l + other.comb.l, self.sync.l + other.sync.l, self.instances + other.instances)
+		return Fragment(self.comb.l + other.comb.l,
+			self.sync.l + other.sync.l,
+			self.instances + other.instances,
+			self.pads | other.pads)
 	def __iadd__(self, other):
 		self.comb.l += other.comb.l
 		self.sync.l += other.sync.l
 		self.instances += other.instances
-		return self
+		self.pads |= other.pads
+		return self

migen/fhdl/verilog.py

@@ -118,6 +118,8 @@ def Convert(f, ios=set(), name="top", clkname="sys_clk", rstname="sys_rst"):
 	
 	clks = Signal(name=clkname)
 	rsts = Signal(name=rstname)
+	
+	ios |= f.pads
 
 	sigs = ListSignals(f)
 	targets = ListTargets(f)