Correct complex inv (#1767)

enzyme/Enzyme/InstructionDerivatives.td

@@ -162,12 +162,20 @@ def CFNeg : SubRoutine<(Op (Op $re, $im):$z),
  (FNeg $re),
  (FNeg $im)
  )>;
+
+def Conj : SubRoutine<(Op (Op $re, $im):$z),
+ (ArrayRet
+ $re,
+ (FNeg $im)
+ )>;
+
 def CFExp : SubRoutine<(Op (Op $re, $im):$z),
  (ArrayRet
  (FMul (FExp $re):$exp, (FCos $im)),
  (FMul $exp, (FSin $im))
  )>;
 
+
 // Same function as the one being called
 def SameFunc {
 }
@@ -826,9 +834,10 @@ def : CallPattern<(Op (Op $x, $y):$z),
 def : CallPattern<(Op (Op $x, $y):$z),
  ["cmplx_inv"],
  [
- (CFDiv (CFNeg (DiffeRet)), (CFMul $z, $z)),
+ // Reverse mode needs to return the conjugate
+ (Conj (CFDiv (CFNeg (Conj (DiffeRet))), (CFMul $z, $z))),
  ],
- (ForwardFromSummedReverse),
+ (CFDiv (CFNeg (Shadow $z)), (CFMul $z, $z)),
  [ReadNone, NoUnwind]
  >;