[Synth][LowerVariadic] Fix a dialect dependency (#9118)

Add comb/hw/synth dialects as a dependency to the pass

Author: uenoku

include/circt/Dialect/Synth/Transforms/SynthPasses.td

@@ -91,6 +91,10 @@ def LowerVariadic : Pass<"synth-lower-variadic", "hw::HWModuleOp"> {
     Option<"timingAware", "timing-aware", "bool", "true",
            "Lower operators with timing information">
   ];
+  let dependentDialects = [
+    "circt::comb::CombDialect", "circt::hw::HWDialect",
+    "circt::synth::SynthDialect"
+  ];
 }
 
 def LowerWordToBits : Pass<"synth-lower-word-to-bits", "hw::HWModuleOp"> {

test/Dialect/Synth/lower-variadic.mlir

@@ -1,5 +1,5 @@
-// RUN: circt-opt %s --synth-lower-variadic | FileCheck %s --check-prefixes=COMMON,TIMING
-// RUN: circt-opt %s --synth-lower-variadic=timing-aware=false | FileCheck %s --check-prefixes=COMMON,NO-TIMING
+// RUN: circt-opt %s --synth-lower-variadic --split-input-file | FileCheck %s --check-prefixes=COMMON,TIMING
+// RUN: circt-opt %s --synth-lower-variadic=timing-aware=false --split-input-file | FileCheck %s --check-prefixes=COMMON,NO-TIMING
 // COMMON-LABEL: hw.module @Basic
 hw.module @Basic(in %a: i2, in %b: i2, in %c: i2, in %d: i2, in %e: i2, out f: i2) {
   // COMMON-NEXT: %[[RES0:.+]] = synth.aig.and_inv not %a, %b : i2
@@ -61,3 +61,13 @@ hw.module @ChildRegion(in %x: i4, in %y: i4, in %z: i4) {
     %1 = comb.and %0, %y, %z : i4
   }
 }
+
+// -----
+// Use a different file to check the dialect dependency.
+// COMMON-LABEL: hw.module @Issue9115
+hw.module @Issue9115(in %a : i16, in %b : i16, in %c : i16, in %d : i16, out product : i16) {
+  %0 = comb.mul %a, %b, %c : i16
+  // COMMON-NEXT: %[[TMP:.+]] = comb.mul %a, %b : i16
+  // COMMON-NEXT: comb.mul %c, %[[TMP]] : i16
+  hw.output %0 : i16
+}