truncate redundant values when exiting a block

benchmarks/wasm/block.wat

@@ -44,7 +44,27 @@
     end
     i32.add
   )
+  (func $test_poly_br (result i32)
+    i32.const -30
+    i32.const 0 ;; unused
+    i32.const 0 ;; unused
+    i32.const 0 ;; unused
+    block (param i32 i32 i32) (result i32 i32)
+      i32.const 0 ;; truncated
+      i32.const 10000 ;; truncated
+      i32.const 10
+      i32.const 20
+      br 0
+      i32.add
+    end
+    i32.add
+    i32.add ;; add value -30 and 30
+    ;; i32.add
+    ;; We can't use i32.add instruction here, because the overflowed value has been truncted
+    ;; when block exited.
+  )
   (export "real_main" (func $real_main))
   (export "test_loop_input" (func $test_loop_input))
   (export "test_if_input" (func $test_if_input))
+  (export "test_poly_br" (func $test_poly_br))
 )

src/main/scala/wasm/MiniWasm.scala

@@ -265,18 +265,19 @@ object Evaluator {
       case Block(ty, inner) =>
         val (inputs, restStack) = stack.splitAt(ty.inps.size)
         val restK: Cont[Ans] = (retStack) =>
-          eval(rest, retStack ++ restStack, frame, kont, trail, ret)
+          eval(rest, retStack.take(ty.out.size) ++ restStack, frame, kont, trail, ret)
         eval(inner, inputs, frame, restK, restK :: trail, ret + 1)
       case Loop(ty, inner) =>
         // We construct two continuations, one for the break (to the begining of the loop),
         // and one for fall-through to the next instruction following the syntactic structure
         // of the program.
         val (inputs, restStack) = stack.splitAt(ty.inps.size)
-        val restK: Cont[Ans] = (retStack) => eval(rest, retStack ++ restStack, frame, kont, trail, ret)
+        val restK: Cont[Ans] = (retStack) =>
+          eval(rest, retStack.take(ty.out.size) ++ restStack, frame, kont, trail, ret)
 
         def loop(retStack: List[Value]): Ans = {
           val k: Cont[Ans] = (retStack) => loop(retStack) // k is just same as loop
-          eval(inner, retStack, frame, restK, k :: trail, ret + 1)
+          eval(inner, retStack.take(ty.inps.size), frame, restK, k :: trail, ret + 1)
         }
 
         loop(inputs)
@@ -285,7 +286,7 @@ object Evaluator {
         val inner = if (cond != 0) thn else els
         val (inputs, restStack) = newStack.splitAt(ty.inps.size)
         val restK: Cont[Ans] = (retStack) =>
-          eval(rest, retStack ++ restStack, frame, kont, trail, ret)
+          eval(rest, retStack.take(ty.out.size) ++ restStack, frame, kont, trail, ret)
         eval(inner, inputs, frame, restK, restK :: trail, ret + 1)
       case Br(label) =>
         trail(label)(stack)

src/test/scala/genwasym/TestEval.scala

@@ -58,6 +58,9 @@ class TestEval extends FunSuite {
   test("input_block.if") {
     testFile("./benchmarks/wasm/block.wat", Some("$test_if_input"), Some(25))
   }
+  test("input_block.poly_br") {
+    testFile("./benchmarks/wasm/block.wat", Some("$test_poly_br"), Some(0))
+  }
 
   // FIXME:
   //test("tribonacci-ret") { testFile("./benchmarks/wasm/tribonacci_ret.wat", None, Some(504)) }