wasm2js: Fix switch lowering, don't fall through after the hoisted parts (#2301)

The switch lowering will "hoist" blocks of code into the JS switch when it can. If it can hoist some but not others, it must not fall through into those others (while it can fall through the hoisted ones - they began as nested blocks with falling-through between them). To fix this, after the hoisted ones issue a break out of the switch (which now contains all the hoisted code, so breaking out of it gets to the code right after the hoisted ones).

fixes #2300

7 files changed, 119 insertions, 0 deletions

diff --git a/test/wasm2js/br_table_hoisting.2asm.js b/test/wasm2js/br_table_hoisting.2asm.js
index e1d743cfe..8d5e45440 100644
--- a/test/wasm2js/br_table_hoisting.2asm.js
+++ b/test/wasm2js/br_table_hoisting.2asm.js
@@ -104,6 +104,7 @@ function asmFunc(global, env, buffer) {
        }
        zed(-1 | 0);
        zed(-2 | 0);
+       break;
       case 0:
        break a;
       case 1:
diff --git a/test/wasm2js/br_table_hoisting.2asm.js.opt b/test/wasm2js/br_table_hoisting.2asm.js.opt
index 44c9d0417..f28214760 100644
--- a/test/wasm2js/br_table_hoisting.2asm.js.opt
+++ b/test/wasm2js/br_table_hoisting.2asm.js.opt
@@ -100,6 +100,7 @@ function asmFunc(global, env, buffer) {
        }
        zed(-1);
        zed(-2);
+       break;
       case 0:
        break a;
       case 1:
@@ -140,6 +141,7 @@ function asmFunc(global, env, buffer) {
        }
        zed(-1);
        zed(-2);
+       break;
       case 0:
        break a;
       case 1:
diff --git a/test/wasm2js/br_table_temp.2asm.js.opt b/test/wasm2js/br_table_temp.2asm.js.opt
index bc29f2c3a..eba815912 100644
--- a/test/wasm2js/br_table_temp.2asm.js.opt
+++ b/test/wasm2js/br_table_temp.2asm.js.opt
@@ -12571,6 +12571,7 @@ function asmFunc(global, env, buffer) {
     $2 = 18;
    case 1:
     $1 = $2 + 1 | 0;
+    break;
    default:
     break block;
    };
@@ -12589,6 +12590,7 @@ function asmFunc(global, env, buffer) {
     $2 = 16;
    case 1:
     $1 = $2 + 1 | 0;
+    break;
    case 0:
     break block;
    };
@@ -12607,6 +12609,7 @@ function asmFunc(global, env, buffer) {
     $2 = 16;
    case 1:
     $1 = $2 + 1 | 0;
+    break;
    default:
     break block;
    };
diff --git a/test/wasm2js/excess_fallthrough.2asm.js b/test/wasm2js/excess_fallthrough.2asm.js
new file mode 100644
index 000000000..e5c4bcd1a
--- /dev/null
+++ b/test/wasm2js/excess_fallthrough.2asm.js
@@ -0,0 +1,55 @@
+
+function asmFunc(global, env, buffer) {
+ var HEAP8 = new global.Int8Array(buffer);
+ var HEAP16 = new global.Int16Array(buffer);
+ var HEAP32 = new global.Int32Array(buffer);
+ var HEAPU8 = new global.Uint8Array(buffer);
+ var HEAPU16 = new global.Uint16Array(buffer);
+ var HEAPU32 = new global.Uint32Array(buffer);
+ var HEAPF32 = new global.Float32Array(buffer);
+ var HEAPF64 = new global.Float64Array(buffer);
+ var Math_imul = global.Math.imul;
+ var Math_fround = global.Math.fround;
+ var Math_abs = global.Math.abs;
+ var Math_clz32 = global.Math.clz32;
+ var Math_min = global.Math.min;
+ var Math_max = global.Math.max;
+ var Math_floor = global.Math.floor;
+ var Math_ceil = global.Math.ceil;
+ var Math_sqrt = global.Math.sqrt;
+ var abort = env.abort;
+ var nan = global.NaN;
+ var infinity = global.Infinity;
+ function bar() {
+  
+ }
+ 
+ function foo($0) {
+  $0 = $0 | 0;
+  label$4 : while (1) {
+   label$5 : {
+    bar();
+    block : {
+     switch (123 | 0) {
+     case 0:
+      bar();
+      break;
+     default:
+      break label$5;
+     };
+    }
+    return;
+   }
+   abort();
+  };
+ }
+ 
+ var FUNCTION_TABLE = [];
+ return {
+  "foo": foo
+ };
+}
+
+var memasmFunc = new ArrayBuffer(65536);
+var retasmFunc = asmFunc({Math,Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array,Uint32Array,Float32Array,Float64Array,NaN,Infinity}, {abort:function() { throw new Error('abort'); }},memasmFunc);
+export var foo = retasmFunc.foo;
diff --git a/test/wasm2js/excess_fallthrough.2asm.js.opt b/test/wasm2js/excess_fallthrough.2asm.js.opt
new file mode 100644
index 000000000..a805107be
--- /dev/null
+++ b/test/wasm2js/excess_fallthrough.2asm.js.opt
@@ -0,0 +1,36 @@
+
+function asmFunc(global, env, buffer) {
+ var HEAP8 = new global.Int8Array(buffer);
+ var HEAP16 = new global.Int16Array(buffer);
+ var HEAP32 = new global.Int32Array(buffer);
+ var HEAPU8 = new global.Uint8Array(buffer);
+ var HEAPU16 = new global.Uint16Array(buffer);
+ var HEAPU32 = new global.Uint32Array(buffer);
+ var HEAPF32 = new global.Float32Array(buffer);
+ var HEAPF64 = new global.Float64Array(buffer);
+ var Math_imul = global.Math.imul;
+ var Math_fround = global.Math.fround;
+ var Math_abs = global.Math.abs;
+ var Math_clz32 = global.Math.clz32;
+ var Math_min = global.Math.min;
+ var Math_max = global.Math.max;
+ var Math_floor = global.Math.floor;
+ var Math_ceil = global.Math.ceil;
+ var Math_sqrt = global.Math.sqrt;
+ var abort = env.abort;
+ var nan = global.NaN;
+ var infinity = global.Infinity;
+ function foo($0) {
+  $0 = $0 | 0;
+  abort();
+ }
+ 
+ var FUNCTION_TABLE = [];
+ return {
+  "foo": foo
+ };
+}
+
+var memasmFunc = new ArrayBuffer(65536);
+var retasmFunc = asmFunc({Math,Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array,Uint32Array,Float32Array,Float64Array,NaN,Infinity}, {abort:function() { throw new Error('abort'); }},memasmFunc);
+export var foo = retasmFunc.foo;
diff --git a/test/wasm2js/excess_fallthrough.wast b/test/wasm2js/excess_fallthrough.wast
new file mode 100644
index 000000000..a31ba88f3
--- /dev/null
+++ b/test/wasm2js/excess_fallthrough.wast
@@ -0,0 +1,21 @@
+(module
+ (export "foo" (func $foo))
+ (func $bar)
+ (func $foo (param $0 i32)
+  (loop $label$4
+   (block $label$5
+    (call $bar)
+    (block
+     (block $label$7
+      (br_table $label$7 $label$5
+       (i32.const 123)
+      )
+     )
+     (call $bar)
+    )
+    (return)
+   )
+   (unreachable)
+  )
+ )
+)
diff --git a/test/wasm2js/switch.2asm.js b/test/wasm2js/switch.2asm.js
index b7583298e..3c2572315 100644
--- a/test/wasm2js/switch.2asm.js
+++ b/test/wasm2js/switch.2asm.js
@@ -46,6 +46,7 @@ function asmFunc(global, env, buffer) {
      j = 101;
     default:
      j = 102;
+     break;
     case 7:
      break $7;
     };