diff --git a/js/src/asmjs/AsmJS.cpp b/js/src/asmjs/AsmJS.cpp
index c33b647953ec..dfc0a0173eae 100644
--- a/js/src/asmjs/AsmJS.cpp
+++ b/js/src/asmjs/AsmJS.cpp
@@ -6500,9 +6500,7 @@ CheckSwitch(FunctionValidator& f, ParseNode* switchStmt)
     if (!f.encoder().writeExpr(Expr::BrTable))
         return false;
 
-    // Write default depth and number of cases (tableLength - 1 + 1 (default)).
-    if (!f.encoder().writeVarU32(defaultDepth))
-        return false;
+    // Write the number of cases (tableLength - 1 + 1 (default)).
     if (!f.encoder().writeVarU32(tableLength))
         return false;
 
@@ -6514,6 +6512,10 @@ CheckSwitch(FunctionValidator& f, ParseNode* switchStmt)
             return false;
     }
 
+    // Write the default depth.
+    if (!f.encoder().writeVarU32(defaultDepth))
+        return false;
+
     // Subtract lowest case value, so that all the cases start from 0.
     if (low) {
         if (!f.encoder().writeExpr(Expr::I32Sub))
diff --git a/js/src/asmjs/Wasm.cpp b/js/src/asmjs/Wasm.cpp
index 083adcec1eaa..0987db301f81 100644
--- a/js/src/asmjs/Wasm.cpp
+++ b/js/src/asmjs/Wasm.cpp
@@ -416,7 +416,7 @@ DecodeBr(FunctionDecoder& f, ExprType expected)
 {
     uint32_t relativeDepth;
     if (!f.d().readVarU32(&relativeDepth))
-        return false;
+        return f.fail("expected relative depth");
 
     if (!f.isLabelInBounds(relativeDepth))
         return f.fail("branch depth exceeds current nesting level");
@@ -429,7 +429,7 @@ DecodeBrIf(FunctionDecoder& f, ExprType expected)
 {
     uint32_t relativeDepth;
     if (!f.d().readVarU32(&relativeDepth))
-        return false;
+        return f.fail("expected relative depth");
 
     if (!f.isLabelInBounds(relativeDepth))
         return f.fail("branch depth exceeds current nesting level");
@@ -438,6 +438,32 @@ DecodeBrIf(FunctionDecoder& f, ExprType expected)
            DecodeExpr(f, ExprType::I32);
 }
 
+static bool
+DecodeBrTable(FunctionDecoder& f)
+{
+    uint32_t tableLength;
+    if (!f.d().readVarU32(&tableLength))
+        return false;
+    if (tableLength > MaxBrTableElems)
+        return f.fail("too many br_table entries");
+
+    for (uint32_t i = 0; i < tableLength; i++) {
+        uint32_t depth;
+        if (!f.d().readVarU32(&depth))
+            return f.fail("missing br_table entry");
+        if (!f.isLabelInBounds(depth))
+            return f.fail("branch depth exceeds current nesting level");
+    }
+
+    uint32_t defaultDepth;
+    if (!f.d().readVarU32(&defaultDepth))
+        return f.fail("expected default relative depth");
+    if (!f.isLabelInBounds(defaultDepth))
+        return f.fail("branch depth exceeds current nesting level");
+
+    return DecodeExpr(f, ExprType::I32);
+}
+
 static bool
 DecodeReturn(FunctionDecoder& f)
 {
@@ -671,6 +697,8 @@ DecodeExpr(FunctionDecoder& f, ExprType expected)
         return DecodeBr(f, expected);
       case Expr::BrIf:
         return DecodeBrIf(f, expected);
+      case Expr::BrTable:
+        return DecodeBrTable(f);
       case Expr::Return:
         return DecodeReturn(f);
       default:
diff --git a/js/src/asmjs/WasmBinary.h b/js/src/asmjs/WasmBinary.h
index 389d8cd99797..d85157419339 100644
--- a/js/src/asmjs/WasmBinary.h
+++ b/js/src/asmjs/WasmBinary.h
@@ -64,7 +64,7 @@ enum class Expr : uint16_t
     // Calls
     Call           = 0x12,
     CallIndirect   = 0x13,
-    CallImport     = 0x09,
+    CallImport     = 0x1f,
 
     // Constants and calls
     I32Const       = 0x0a,
@@ -827,6 +827,7 @@ static const unsigned MaxImports         =   4 * 1024;
 static const unsigned MaxExports         =   4 * 1024;
 static const unsigned MaxTableElems      = 128 * 1024;
 static const unsigned MaxArgsPerFunc     =   4 * 1024;
+static const unsigned MaxBrTableElems    =   4 * 1024;
 
 } // namespace wasm
 } // namespace js
diff --git a/js/src/asmjs/WasmIonCompile.cpp b/js/src/asmjs/WasmIonCompile.cpp
index f2f015c89ec3..41855a983b15 100644
--- a/js/src/asmjs/WasmIonCompile.cpp
+++ b/js/src/asmjs/WasmIonCompile.cpp
@@ -2524,16 +2524,8 @@ EmitIfElse(FunctionCompiler& f, bool hasElse, ExprType expected, MDefinition** d
 static bool
 EmitBrTable(FunctionCompiler& f)
 {
-    uint32_t defaultDepth = f.readVarU32();
     uint32_t numCases = f.readVarU32();
 
-    // Empty table
-    if (!numCases) {
-        MDefinition* _;
-        return EmitExpr(f, ExprType::I32, &_) &&
-               f.br(defaultDepth);
-    }
-
     BlockVector cases;
     if (!cases.resize(numCases))
         return false;
@@ -2545,10 +2537,16 @@ EmitBrTable(FunctionCompiler& f)
     for (size_t i = 0; i < numCases; i++)
         depths[i] = f.readVarU32();
 
+    uint32_t defaultDepth = f.readVarU32();
+
     MDefinition* index;
     if (!EmitExpr(f, ExprType::I32, &index))
         return false;
 
+    // Empty table
+    if (!numCases)
+        return f.br(defaultDepth);
+
     MBasicBlock* switchBlock;
     if (!f.startSwitch(index, numCases, &switchBlock))
         return false;
diff --git a/js/src/asmjs/WasmText.cpp b/js/src/asmjs/WasmText.cpp
index 59c1e5555e44..378894d9f8b9 100644
--- a/js/src/asmjs/WasmText.cpp
+++ b/js/src/asmjs/WasmText.cpp
@@ -3154,10 +3154,9 @@ class Resolver
         return ref.name().empty() || resolveRef(varMap_, ref);
     }
     bool resolveTarget(WasmRef& ref) {
-        for (size_t i = targetStack_.length(); i > 0; i--) {
-            uint32_t targetIndex = i - 1;
-            if (targetStack_[targetIndex] == ref.name()) {
-                ref.setIndex(targetIndex);
+        for (size_t i = 0, e = targetStack_.length(); i < e; i++) {
+            if (targetStack_[e - i - 1] == ref.name()) {
+                ref.setIndex(i);
                 return true;
             }
         }
@@ -3659,9 +3658,6 @@ EncodeBranchTable(Encoder& e, WasmAstBranchTable& bt)
     if (!e.writeExpr(Expr::BrTable))
         return false;
 
-    if (!e.writeVarU32(bt.def().index()))
-        return false;
-
     if (!e.writeVarU32(bt.table().length()))
         return false;
 
@@ -3670,6 +3666,9 @@ EncodeBranchTable(Encoder& e, WasmAstBranchTable& bt)
             return false;
     }
 
+    if (!e.writeVarU32(bt.def().index()))
+        return false;
+
     return EncodeExpr(e, bt.index());
 }
 
diff --git a/js/src/jit-test/tests/wasm/basic-control-flow.js b/js/src/jit-test/tests/wasm/basic-control-flow.js
index 14774b9cab6d..a9247fef8abd 100644
--- a/js/src/jit-test/tests/wasm/basic-control-flow.js
+++ b/js/src/jit-test/tests/wasm/basic-control-flow.js
@@ -147,33 +147,266 @@ assertThrowsInstanceOf(() => wasmEvalText('(module (func (return (i32.const 1)))
 // ----------------------------------------------------------------------------
 // br / br_if
 
-wasmTextToBinary('(module (func (br 0)))');
-wasmTextToBinary('(module (func (block (br 0))))');
-wasmTextToBinary('(module (func (block $l (br $l))))');
-wasmTextToBinary('(module (func (br_if 0 (i32.const 0))))');
-wasmTextToBinary('(module (func (result i32) (block (br_if 0 (i32.const 1)))))');
-wasmTextToBinary('(module (func (result i32) (block $l (br_if $l (i32.const 1)))))');
-
-wasmTextToBinary('(module (func (block $l (block $m (br $l)))))');
-wasmTextToBinary('(module (func (block $l (block $m (br $m)))))');
-
-assertErrorMessage(() => wasmEvalText('(module (func (br 1)))'), TypeError, /branch depth exceeds current nesting level/);
-assertErrorMessage(() => wasmEvalText('(module (func (br_if 1 (i32.const 0))))'), TypeError, /branch depth exceeds current nesting level/);
 assertErrorMessage(() => wasmEvalText('(module (func (result i32) (block (br 0))) (export "" 0))'), TypeError, mismatchError("void", "i32"));
 assertErrorMessage(() => wasmEvalText('(module (func (result i32) (block (br_if 0 (i32.const 0)))) (export "" 0))'), TypeError, mismatchError("void", "i32"));
 
+const DEPTH_OUT_OF_BOUNDS = /branch depth exceeds current nesting level/;
+
+assertErrorMessage(() => wasmEvalText('(module (func (br 0)))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+assertErrorMessage(() => wasmEvalText('(module (func (block (br 1))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+assertErrorMessage(() => wasmEvalText('(module (func (loop (br 2))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+
+assertErrorMessage(() => wasmEvalText('(module (func (br_if 0 (i32.const 0))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+assertErrorMessage(() => wasmEvalText('(module (func (block (br_if 1 (i32.const 0)))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+assertErrorMessage(() => wasmEvalText('(module (func (loop (br_if 2 (i32.const 0)))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+
+assertErrorMessage(() => wasmEvalText(`(module (func (result i32)
+  (block
+    (if_else
+      (br 0)
+      (i32.const 0)
+      (i32.const 2)
+    )
+  )
+) (export "" 0))`), TypeError, mismatchError("void", "i32"));
+
+assertErrorMessage(() => wasmEvalText(`(module (func (block $out (br_if $out (br 0)))) (export "" 0))`), TypeError, mismatchError("void", "i32"));
+
+assertEq(wasmEvalText('(module (func (block (br 0))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (block $l (br $l))) (export "" 0))')(), undefined);
+
+assertEq(wasmEvalText('(module (func (block (block (br 1)))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (block $l (block (br $l)))) (export "" 0))')(), undefined);
+
+assertEq(wasmEvalText('(module (func (block $l (block $m (br $l)))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (block $l (block $m (br $m)))) (export "" 0))')(), undefined);
+
+assertEq(wasmEvalText(`(module (func (result i32)
+  (block
+    (br 0)
+    (return (i32.const 0))
+  )
+  (return (i32.const 1))
+) (export "" 0))`)(), 1);
+
+assertEq(wasmEvalText(`(module (func (result i32)
+  (block
+    (block
+      (br 0)
+      (return (i32.const 0))
+    )
+    (return (i32.const 1))
+  )
+  (return (i32.const 2))
+) (export "" 0))`)(), 1);
+
+assertEq(wasmEvalText(`(module (func (result i32)
+  (block $outer
+    (block $inner
+      (br $inner)
+      (return (i32.const 0))
+    )
+    (return (i32.const 1))
+  )
+  (return (i32.const 2))
+) (export "" 0))`)(), 1);
+
+// TODO enable once bug 1253572 is fixed.
+/*
+var notcalled = false;
+var called = false;
+var imports = {
+    notcalled() {notcalled = true},
+    called() {called = true}
+};
+assertEq(wasmEvalText(`(module (import "inc" "") (func
+  (block
+    (return (br 0))
+    (call_import 0)
+  )
+  (call_import 1)
+) (export "" 0))`)(imports), undefined);
+assertEq(notcalled, false);
+assertEq(called, true);
+
+assertEq(wasmEvalText(`(module (func
+  (block
+    (i32.add
+      (i32.const 0)
+      (return (br 0))
+    )
+  )
+  (return)
+) (export "" 0))`)(), 1);
+*/
+
+assertEq(wasmEvalText(`(module (func (result i32)
+  (block
+    (if_else
+      (i32.const 1)
+      (br 0)
+      (return (i32.const 0))
+    )
+  )
+  (return (i32.const 1))
+) (export "" 0))`)(), 1);
+
+assertEq(wasmEvalText('(module (func (block (br_if 0 (i32.const 1)))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (block (br_if 0 (i32.const 0)))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (block $l (br_if $l (i32.const 1)))) (export "" 0))')(), undefined);
+
+var isNonZero = wasmEvalText(`(module (func (result i32) (param i32)
+  (block
+    (br_if 0 (get_local 0))
+    (return (i32.const 0))
+  )
+  (return (i32.const 1))
+) (export "" 0))`);
+
+assertEq(isNonZero(0), 0);
+assertEq(isNonZero(1), 1);
+assertEq(isNonZero(-1), 1);
+
 // ----------------------------------------------------------------------------
 // loop
 
-wasmTextToBinary('(module (func (loop (br 0))))');
-wasmTextToBinary('(module (func (loop (br 1))))');
-wasmTextToBinary('(module (func (loop $a (br $a))))');
-wasmTextToBinary('(module (func (loop $a $b (br $a))))');
-wasmTextToBinary('(module (func (loop $a $b (br $b))))');
-wasmTextToBinary('(module (func (loop $a $a (br $a))))');
+assertErrorMessage(() => wasmEvalText('(module (func (loop (br 2))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+
+assertEq(wasmEvalText('(module (func (loop)) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (result i32) (loop (i32.const 2)) (i32.const 1)) (export "" 0))')(), 1);
+
+assertEq(wasmEvalText('(module (func (loop (br 1))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (loop $a (br $a))) (export "" 0))')(), undefined);
+assertEq(wasmEvalText('(module (func (loop $a $b (br $a))) (export "" 0))')(), undefined);
+
+assertEq(wasmEvalText(`(module (func (result i32) (local i32)
+  (loop
+    $break $continue
+    (if
+      (i32.gt_u (get_local 0) (i32.const 5))
+      (br $break)
+    )
+    (set_local 0 (i32.add (get_local 0) (i32.const 1)))
+    (br $continue)
+  )
+  (return (get_local 0))
+) (export "" 0))`)(), 6);
+
+assertEq(wasmEvalText(`(module (func (result i32) (local i32)
+  (loop
+    $break $continue
+    (br_if
+      $break
+      (i32.gt_u (get_local 0) (i32.const 5))
+    )
+    (set_local 0 (i32.add (get_local 0) (i32.const 1)))
+    (br $continue)
+  )
+  (return (get_local 0))
+) (export "" 0))`)(), 6);
+
+assertEq(wasmEvalText(`(module (func (result i32) (local i32)
+  (loop
+    $break $continue
+    (set_local 0 (i32.add (get_local 0) (i32.const 1)))
+    (br_if
+      $continue
+      (i32.le_u (get_local 0) (i32.const 5))
+    )
+  )
+  (return (get_local 0))
+) (export "" 0))`)(), 6);
+
+assertEq(wasmEvalText(`(module (func (result i32) (local i32)
+  (loop
+    $break $continue
+    (br_if
+      $break
+      (i32.gt_u (get_local 0) (i32.const 5))
+    )
+    (set_local 0 (i32.add (get_local 0) (i32.const 1)))
+    (loop
+      (br $continue)
+    )
+    (return (i32.const 42))
+  )
+  (return (get_local 0))
+) (export "" 0))`)(), 6);
+
+assertEq(wasmEvalText(`(module (func (result i32) (local i32)
+  (loop
+    $break $continue
+    (set_local 0 (i32.add (get_local 0) (i32.const 1)))
+    (loop
+      (br_if
+        $continue
+        (i32.le_u (get_local 0) (i32.const 5))
+      )
+    )
+    (br $break)
+  )
+  (return (get_local 0))
+) (export "" 0))`)(), 6);
 
 // ----------------------------------------------------------------------------
-// tableswitch
+// br_table
+
+assertErrorMessage(() => wasmEvalText('(module (func (br_table (i32.const 0) (table) (br 0))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+
+assertErrorMessage(() => wasmEvalText('(module (func (block (br_table (i32.const 0) (table (br 2)) (br 0)))))'), TypeError, DEPTH_OUT_OF_BOUNDS);
+
+assertErrorMessage(() => wasmEvalText('(module (func (block (br_table (f32.const 0) (table) (br 0)))))'), TypeError, mismatchError("f32", "i32"));
+
+assertEq(wasmEvalText(`(module (func (result i32) (param i32)
+  (block $default
+   (br_table (get_local 0) (table) (br $default))
+   (return (i32.const 0))
+  )
+  (return (i32.const 1))
+) (export "" 0))`)(), 1);
+
+assertEq(wasmEvalText(`(module (func (result i32) (param i32)
+  (block $default
+   (br_table (return (i32.const 1)) (table) (br $default))
+   (return (i32.const 0))
+  )
+  (return (i32.const 2))
+) (export "" 0))`)(), 1);
+
+assertEq(wasmEvalText(`(module (func (result i32) (param i32)
+  (block $outer
+   (block $inner
+    (br_table (get_local 0) (table) (br $inner))
+    (return (i32.const 0))
+   )
+   (return (i32.const 1))
+  )
+  (return (i32.const 2))
+) (export "" 0))`)(), 1);
+
+var f = wasmEvalText(`(module (func (result i32) (param i32)
+  (block $0
+   (block $1
+    (block $2
+     (block $default
+      (br_table
+       (get_local 0)
+       (table (br $0) (br $1) (br $2))
+       (br $default)
+      )
+     )
+     (return (i32.const -1))
+    )
+    (return (i32.const 2))
+   )
+  )
+  (return (i32.const 0))
+) (export "" 0))`);
+
+assertEq(f(-2), -1);
+assertEq(f(-1), -1);
+assertEq(f(0), 0);
+assertEq(f(1), 0);
+assertEq(f(2), 2);
+assertEq(f(3), -1);
 
-wasmTextToBinary('(module (func (param i32) (block $b1 (block $b2 (br_table (get_local 0) (table (br $b1) (br $b2)) (br $b2))))))');
-wasmTextToBinary('(module (func (param i32) (block $b1 (br_table (get_local 0) (table) (br $b1)))))');
diff --git a/js/src/jit-test/tests/wasm/timeout-no-signals.js b/js/src/jit-test/tests/wasm/timeout-no-signals.js
new file mode 100644
index 000000000000..08107a04d5ee
--- /dev/null
+++ b/js/src/jit-test/tests/wasm/timeout-no-signals.js
@@ -0,0 +1,7 @@
+// |jit-test| exitstatus: 6;
+load(libdir + "wasm.js");
+
+setJitCompilerOption("signals.enable", 0);
+timeout(1);
+wasmEvalText('(module (func (loop (br 0))) (export "" 0))')();
+assertEq(true, false);
diff --git a/js/src/jit-test/tests/wasm/timeout.js b/js/src/jit-test/tests/wasm/timeout.js
new file mode 100644
index 000000000000..b18bdb4e5350
--- /dev/null
+++ b/js/src/jit-test/tests/wasm/timeout.js
@@ -0,0 +1,6 @@
+// |jit-test| exitstatus: 6;
+load(libdir + "wasm.js");
+
+timeout(1);
+wasmEvalText('(module (func (loop (br 0))) (export "" 0))')();
+assertEq(true, false);