From 5f0dc6be0c0ea12dfa8368d6f17df2dcad2b2866 Mon Sep 17 00:00:00 2001
From: Zachary Snow <zach@zachjs.com>
Date: Mon, 25 Jan 2021 12:29:34 -0500
Subject: [PATCH] preserve generate else branch association in codegen

---
 src/Language/SystemVerilog/AST/GenItem.hs | 16 +++++-
 test/basic/generate_else_branch.sv        | 62 +++++++++++++++++++++++
 2 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 test/basic/generate_else_branch.sv

diff --git a/src/Language/SystemVerilog/AST/GenItem.hs b/src/Language/SystemVerilog/AST/GenItem.hs
index 994d3f5..e05dc6a 100644
--- a/src/Language/SystemVerilog/AST/GenItem.hs
+++ b/src/Language/SystemVerilog/AST/GenItem.hs
@@ -38,7 +38,7 @@ instance Show GenItem where
         printf "case (%s)\n%s\nendcase" (show e) bodyStr
         where bodyStr = indent $ unlines' $ map showGenCase cs
     show (GenIf e a GenNull) = printf "if (%s) %s"          (show e) (show a)
-    show (GenIf e a b      ) = printf "if (%s) %s\nelse %s" (show e) (show a) (show b)
+    show (GenIf e a b      ) = printf "if (%s) %s\nelse %s" (show e) (showBlockedBranch a) (show b)
     show (GenFor (x1, e1) c (x2, o2, e2) s) =
         printf "for (%s = %s; %s; %s %s %s) %s"
             x1 (show e1)
@@ -48,6 +48,20 @@ instance Show GenItem where
     show (GenNull) = ";"
     show (GenModuleItem item) = show item
 
+showBlockedBranch :: GenItem -> String
+showBlockedBranch genItem =
+    show $
+    if isControl genItem
+        then GenBlock "" [genItem]
+        else genItem
+    where
+        isControl :: GenItem -> Bool
+        isControl GenIf{} = True
+        isControl GenFor{} = True
+        isControl GenCase{} = True
+        isControl GenModuleItem{} = True
+        isControl _ = False
+
 type GenCase = ([Expr], GenItem)
 
 showGenCase :: GenCase -> String
diff --git a/test/basic/generate_else_branch.sv b/test/basic/generate_else_branch.sv
new file mode 100644
index 0000000..a93c075
--- /dev/null
+++ b/test/basic/generate_else_branch.sv
@@ -0,0 +1,62 @@
+module Example;
+    parameter X = 1;
+    parameter Y = 1;
+    parameter Z = 1;
+    initial $display("X=%0d Y=%0d Z=%0d Example", X, Y, Z);
+    generate
+        if (X) begin
+            if (Y) begin
+                if (Z) begin
+                    initial $display("X=%0d Y=%0d Z=%0d A", X, Y, Z);
+                end
+            end
+            else begin
+                initial $display("X=%0d Y=%0d Z=%0d B", X, Y, Z);
+            end
+        end
+        initial
+            if (X) begin
+                if (Y) begin
+                    if (Z) begin
+                        $display("X=%0d Y=%0d Z=%0d C", X, Y, Z);
+                    end
+                end
+                else begin
+                    $display("X=%0d Y=%0d Z=%0d D", X, Y, Z);
+                end
+            end
+        if (X) begin
+            initial
+                if (Y) begin
+                    if (Z) begin
+                        $display("X=%0d Y=%0d Z=%0d E", X, Y, Z);
+                    end
+                end
+                else begin
+                    $display("X=%0d Y=%0d Z=%0d F", X, Y, Z);
+                end
+        end
+        if (X) begin
+            if (Y) begin
+                initial
+                    if (Z) begin
+                        $display("X=%0d Y=%0d Z=%0d G", X, Y, Z);
+                    end
+            end
+            else begin
+                initial $display("X=%0d Y=%0d Z=%0d H", X, Y, Z);
+            end
+        end
+    endgenerate
+endmodule
+
+module top;
+    Example #(0, 0, 0) e000();
+    Example #(0, 0, 1) e001();
+    Example #(0, 1, 0) e010();
+    Example #(0, 1, 1) e011();
+    Example #(1, 0, 0) e100();
+    Example #(1, 0, 1) e101();
+    Example #(1, 1, 0) e110();
+    Example #(1, 1, 1) e111();
+endmodule