From 84d73b94aac932f2b1e545446a4c0b8720c04545 Mon Sep 17 00:00:00 2001
From: Martin Erhart <maerhart@outlook.com>
Date: Fri, 9 Aug 2024 08:46:31 +0100
Subject: [PATCH] [MooreToCore] Fix variable op lowering of aggregate types
 (#7481)

---
 lib/Conversion/MooreToCore/MooreToCore.cpp | 22 ++++++++++++++--------
 test/Conversion/MooreToCore/basic.mlir     | 17 ++++++++++++++---
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/lib/Conversion/MooreToCore/MooreToCore.cpp b/lib/Conversion/MooreToCore/MooreToCore.cpp
index ac741f9e9d..f6b53d77d7 100644
--- a/lib/Conversion/MooreToCore/MooreToCore.cpp
+++ b/lib/Conversion/MooreToCore/MooreToCore.cpp
@@ -158,6 +158,7 @@ struct VariableOpConversion : public OpConversionPattern<VariableOp> {
   LogicalResult
   matchAndRewrite(VariableOp op, OpAdaptor adaptor,
                   ConversionPatternRewriter &rewriter) const override {
+    Location loc = op.getLoc();
     Type resultType = typeConverter->convertType(op.getResult().getType());
     Value init = adaptor.getInitial();
     // TODO: Unsupport x/z, so the initial value is 0.
@@ -165,10 +166,18 @@ struct VariableOpConversion : public OpConversionPattern<VariableOp> {
                      Domain::FourValued)
       return failure();
 
-    if (!init)
-      init = rewriter.create<hw::ConstantOp>(op->getLoc(), resultType, 0);
-    rewriter.replaceOpWithNewOp<llhd::SigOp>(op, hw::InOutType::get(resultType),
-                                             op.getNameAttr(), init);
+    if (!init) {
+      Type elementType = cast<hw::InOutType>(resultType).getElementType();
+      int64_t width = hw::getBitWidth(elementType);
+      if (width == -1)
+        return failure();
+
+      Value constZero = rewriter.create<hw::ConstantOp>(loc, APInt(width, 0));
+      init = rewriter.createOrFold<hw::BitcastOp>(loc, elementType, constZero);
+    }
+
+    rewriter.replaceOpWithNewOp<llhd::SigOp>(op, resultType, op.getNameAttr(),
+                                             init);
     return success();
   }
 };
@@ -715,10 +724,7 @@ static void populateTypeConversion(TypeConverter &typeConverter) {
   });
 
   typeConverter.addConversion([&](RefType type) -> std::optional<Type> {
-    if (isa<IntType, ArrayType, UnpackedArrayType>(type.getNestedType()))
-      return mlir::IntegerType::get(type.getContext(),
-                                    type.getBitSize().value());
-    return std::nullopt;
+    return hw::InOutType::get(typeConverter.convertType(type.getNestedType()));
   });
 
   // Valid target types.
diff --git a/test/Conversion/MooreToCore/basic.mlir b/test/Conversion/MooreToCore/basic.mlir
index 0722144b29..1df63b4ea9 100644
--- a/test/Conversion/MooreToCore/basic.mlir
+++ b/test/Conversion/MooreToCore/basic.mlir
@@ -312,9 +312,20 @@ moore.module @Variable() {
   moore.output
 }
 
-// CHECK-LABEL: func @Struct
-func.func @Struct(%arg0: !moore.struct<{exp_bits: i32, man_bits: i32}>) -> !moore.i32 {
+// CHECK-LABEL: hw.module @Struct
+moore.module @Struct(in %arg0 : !moore.struct<{exp_bits: i32, man_bits: i32}>, out a : !moore.i32, out b : !moore.struct<{exp_bits: i32, man_bits: i32}>, out c : !moore.struct<{exp_bits: i32, man_bits: i32}>) {
   // CHECK: hw.struct_extract %arg0["exp_bits"] : !hw.struct<exp_bits: i32, man_bits: i32>
   %0 = moore.struct_extract %arg0, "exp_bits" : !moore.struct<{exp_bits: i32, man_bits: i32}> -> i32
-  return %0 : !moore.i32
+  
+  // CHECK: [[C0:%.+]] = hw.constant 0 : i64
+  // CHECK: [[INIT:%.+]] = hw.bitcast [[C0]] : (i64) -> !hw.struct<exp_bits: i32, man_bits: i32>
+  // CHECK: llhd.sig "" [[INIT]] : !hw.struct<exp_bits: i32, man_bits: i32>
+  // CHECK: llhd.sig "" %arg0 : !hw.struct<exp_bits: i32, man_bits: i32>
+  %1 = moore.variable : <struct<{exp_bits: i32, man_bits: i32}>>
+  %2 = moore.variable %arg0 : <struct<{exp_bits: i32, man_bits: i32}>>
+
+  %3 = moore.read %1 : <struct<{exp_bits: i32, man_bits: i32}>>
+  %4 = moore.read %2 : <struct<{exp_bits: i32, man_bits: i32}>>
+
+  moore.output %0, %3, %4 : !moore.i32, !moore.struct<{exp_bits: i32, man_bits: i32}>, !moore.struct<{exp_bits: i32, man_bits: i32}>
 }