fold concatenations of number literals

src/Convert/ExprUtils.hs

@@ -36,6 +36,10 @@ simplifyStep (UniOp LogNot (BinOp Ne a b)) = BinOp Eq a b
 simplifyStep (UniOp UniSub (UniOp UniSub e)) = e
 simplifyStep (UniOp UniSub (BinOp Sub e1 e2)) = BinOp Sub e2 e1
 
+simplifyStep (Concat (Number n1 : Number n2 : rest)) =
+    simplifyStep $ Concat $ Number n : rest
+    where n = n1 <> n2
+
 simplifyStep (Concat [Number (Decimal size _ value)]) =
     Number $ Decimal size False value
 simplifyStep (Concat [Number (Based size _ base value kinds)]) =

src/Language/SystemVerilog/AST/Number.hs

@@ -14,6 +14,7 @@ module Language.SystemVerilog.AST.Number
     , numberToInteger
     ) where
 
+import Data.Bits (shiftL)
 import Data.Char (digitToInt, intToDigit, toLower)
 import Data.List (elemIndex)
 import Text.Read (readMaybe)
@@ -300,3 +301,35 @@ chunk base n0 =
                 0 -> [d']
                 _ -> d' : chunkStep (quotRem n base)
             where d' = fromIntegral d
+
+-- number concatenation
+instance Semigroup Number where
+    (n1 @ Based{}) <> (n2 @ Based{}) =
+        Based size signed base values kinds
+        where
+            size = size1 + size2
+            signed = False
+            base =
+                if kinds1 == 0 && kinds2 == 0
+                    then min base1 base2
+                    else Binary
+            values = values2 + shiftL values1 size2
+            kinds = kinds2 + shiftL kinds1 size2
+            size1 = fromIntegral $ numberBitLength n1
+            size2 = fromIntegral $ numberBitLength n2
+            Based _ _ base1 values1 kinds1 = n1
+            Based _ _ base2 values2 kinds2 = n2
+    n1 <> n2 =
+        toBased n1 <> toBased n2
+        where
+            toBased (n @ Based{}) = n
+            toBased (Decimal size signed num) =
+                Based size signed Hex num 0
+            toBased (UnbasedUnsized ch) =
+                case ch of
+                    '0' -> based 0 0
+                    '1' -> based 1 0
+                    'x' -> based 0 1
+                    'z' -> based 1 1
+                    _ -> error $ "invalid unbased unsized char: " ++ show ch
+                where based = Based 1 False Binary

test/basic/number_concat.sv

@@ -0,0 +1,17 @@
+`define TEST(x, y) $display("{%b, %b} => %b", x, y, {x, y});
+
+module top;
+    initial begin
+        `TEST('z, 'x);
+        `TEST('1, '0);
+        `TEST(2'sh3, 32'd0);
+        `TEST(3'sh4, 32'd0);
+        `TEST(3'sb101, 32'd0);
+        `TEST('sh3, 32'd0);
+        `TEST('sh4, 32'd0);
+        `TEST('b0101, 32'd0);
+        `TEST('sh3, 'd0);
+        `TEST('sh4, 'd0);
+        `TEST('b0101, 'd0);
+    end
+endmodule

test/basic/number_concat.v

@@ -0,0 +1,17 @@
+`define TEST(x, y) $display("{%b, %b} => %b", x, y, {x, y});
+
+module top;
+    initial begin
+        `TEST(1'sbz, 1'sbx);
+        `TEST(1'sb1, 1'sb0);
+        `TEST(2'sh3, 32'd0);
+        `TEST(3'sh4, 32'd0);
+        `TEST(3'sb101, 32'd0);
+        `TEST(32'sh3, 32'd0);
+        `TEST(32'sh4, 32'd0);
+        `TEST(32'sb0101, 32'd0);
+        `TEST(32'sh3, 32'd0);
+        `TEST(32'sh4, 32'd0);
+        `TEST(32'sb0101, 32'd0);
+    end
+endmodule