From 99c20c4b35773b45182b91d9fee764ddab6c708e Mon Sep 17 00:00:00 2001
From: Denys Zadorozhnyi <denys@zadorozhnyi.com>
Date: Tue, 19 Sep 2023 14:55:40 +0300
Subject: [PATCH] fix: handle missing `Instruction::Switch` in jump destination
 changes

Add `Instruction::Switch` in destination branch argument appending with
panic since we don't support block arguments in `Switch` instruction.
---
 frontend-wasm/src/function_builder_ext.rs | 15 +++++++++++++++
 hir/src/dataflow.rs                       |  8 ++++++++
 2 files changed, 23 insertions(+)

diff --git a/frontend-wasm/src/function_builder_ext.rs b/frontend-wasm/src/function_builder_ext.rs
index 2ad61c0b..f3df9a0f 100644
--- a/frontend-wasm/src/function_builder_ext.rs
+++ b/frontend-wasm/src/function_builder_ext.rs
@@ -355,6 +355,21 @@ impl<'a> FunctionBuilderExt<'a> {
                     *else_dest = new_block;
                 }
             }
+            Instruction::Switch(Switch {
+                op: _,
+                arg: _,
+                ref mut arms,
+                ref mut default,
+            }) => {
+                for (_, ref mut dest_block) in arms {
+                    if dest_block == &old_block {
+                        *dest_block = new_block;
+                    }
+                }
+                if default == &old_block {
+                    *default = new_block;
+                }
+            }
             _ => panic!("{} must be a branch instruction", inst),
         }
         self.func_ctx.ssa.declare_block_predecessor(new_block, inst);
diff --git a/hir/src/dataflow.rs b/hir/src/dataflow.rs
index d5b8e605..2ece7c30 100644
--- a/hir/src/dataflow.rs
+++ b/hir/src/dataflow.rs
@@ -647,6 +647,14 @@ impl DataFlowGraph {
                     else_args.push(value, &mut self.value_lists);
                 }
             }
+            Instruction::Switch(Switch {
+                op: _,
+                arg: _,
+                arms: _,
+                default: _,
+            }) => {
+                panic!("cannot append argument {value} to Switch destination block {dest}, since it has no block arguments support");
+            }
             _ => panic!("{} must be a branch instruction", branch_inst),
         }
     }