[FIRRTL] Make IMCP work with Layers

Change IMCP to recurse into layers. This has the effect of allowing IMCP to sink constants into layers and to properly visit instances which are instantiated under layers. Signed-off-by: Schuyler Eldridge <[email protected]>
llvm · Sep 13, 2024 · 3eadefc · 3eadefc
1 parent 46014cd
commit 3eadefc
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diff --git a/lib/Dialect/FIRRTL/Transforms/IMConstProp.cpp b/lib/Dialect/FIRRTL/Transforms/IMConstProp.cpp
@@ -483,6 +483,8 @@ void IMConstPropPass::markBlockExecutable(Block *block) {
         .Case<InstanceOp>([&](auto instance) { markInstanceOp(instance); })
         .Case<ObjectOp>([&](auto obj) { markObjectOp(obj); })
         .Case<MemOp>([&](auto mem) { markMemOp(mem); })
+        .Case<LayerBlockOp>(
+            [&](auto layer) { markBlockExecutable(layer.getBody(0)); })
         .Default([&](auto _) {
           if (isa<mlir::UnrealizedConversionCastOp, VerbatimExprOp,
                   VerbatimWireOp, SubaccessOp>(op) ||

diff --git a/test/Dialect/FIRRTL/imconstprop.mlir b/test/Dialect/FIRRTL/imconstprop.mlir
@@ -950,3 +950,20 @@ firrtl.circuit "OMIRRemoval" {
     firrtl.matchingconnect %d, %tmp_3 : !firrtl.uint<4>
   }
 }
+
+
+// -----
+
+firrtl.circuit "Layers" {
+  // CHECK-LABEL: firrtl.module @Layers
+  firrtl.layer @A bind {}
+  firrtl.module @Layers() {
+    %c0_ui1 = firrtl.constant 0 : !firrtl.uint<1>
+    // CHECK: firrtl.layerblock
+    firrtl.layerblock @A {
+      %a = firrtl.node %c0_ui1 : !firrtl.uint<1>
+      // CHECK-NEXT: %b = firrtl.node sym @sym_b %c0_ui1
+      %b = firrtl.node sym @sym_b %a : !firrtl.uint<1>
+    }
+  }
+}