Fixed Pad inference bug

3 files changed, 33 insertions, 3 deletions

diff --git a/TODO b/TODO
index 4a099d94..818b78c3 100644
--- a/TODO
+++ b/TODO
@@ -7,8 +7,6 @@ on-reset
 Parser
    Error if incorrectly assign stuff, like use = instead of :=
    Update parser and update tests
-Change all primops to be strict on data widths
-Add pad!
 Make instances always male, flip the bundles on declaration
 dlsh,drsh
 move Infer-Widths to before vec expansion?
@@ -32,6 +30,12 @@ Well-formed high firrtl
 After adding dynamic assertions, insert bounds check with accessor expansion
 Well-formed low firrtl
    All things only assigned to once
+Width inference
+   No names
+   No Unknowns
+   All widths are positive
+   Pad's width is greater than value's width
+   pad's width is greater than value's width
 
 ======== Other Passes ========
 constant folding (partial eval) pass
diff --git a/src/main/stanza/passes.stanza b/src/main/stanza/passes.stanza
index 588b4b73..50d2831a 100644
--- a/src/main/stanza/passes.stanza
+++ b/src/main/stanza/passes.stanza
@@ -1584,7 +1584,7 @@ defn gen-constraints (m:Module, h:HashTable<Symbol,Type>, v:Vector<WGeq>) -> Mod
          (e:Pad) : 
             val value-w = width!(value(e))
             val pad-w = remove-unknowns-w(width(e))
-            ;add(v,WGeq(pad-w, IntWidth(0)))
+            add(v,WGeq(pad-w, value-w))
             val pad-t = match(type(e)) :
                (t:UIntType) : UIntType(pad-w)
                (t:SIntType) : SIntType(pad-w)
diff --git a/test/passes/jacktest/gcd2.fir b/test/passes/jacktest/gcd2.fir
new file mode 100644
index 00000000..e6700122
--- /dev/null
+++ b/test/passes/jacktest/gcd2.fir
@@ -0,0 +1,26 @@
+; RUN: firrtl -i %s -o %s.flo -x X -p cTwd | tee %s.out | FileCheck %s
+;CHECK: To Flo
+circuit GCD : 
+  module GCD : 
+    input b : UInt(16)
+    input a : UInt(16)
+    input e : UInt(1)
+    output z : UInt(16)
+    output v : UInt(1)
+    
+    reg x : UInt(16)
+    reg y : UInt(16)
+    node T_17 = gt(Pad(x,?), Pad(y,?))
+    when T_17 : 
+      node T_18 = sub-wrap(Pad(x,?), Pad(y,?))
+      x := T_18
+    else : 
+      node T_19 = sub-wrap(Pad(y,?), Pad(x,?))
+      y := T_19
+    when e : 
+      x := a
+      y := b
+    z := x
+    node T_20 = UInt(0, 1)
+    node T_21 = eq(Pad(y,?), Pad(T_20,?))
+    v := T_21