diff --git a/JSTests/stress/dfg-parseIntResult-should-not-wrap-above-int32.js b/JSTests/stress/dfg-parseIntResult-should-not-wrap-above-int32.js
new file mode 100644
index 0000000000000..13e9f3dbfd67b
--- /dev/null
+++ b/JSTests/stress/dfg-parseIntResult-should-not-wrap-above-int32.js
@@ -0,0 +1,38 @@
+// parseInt results outside int32 range must be boxed as doubles, not
+// sign-wrapped int32s, once the call site tiers up to the DFG/FTL.
+// parseIntResult() used to do static_cast<int>(input) before the round-trip
+// comparison deciding int32 vs double boxing; the cast is undefined behavior
+// for out-of-range inputs, which let LTO fold the overflow guard away.
+
+function hex(s) {
+    return parseInt(s, 16);
+}
+noInline(hex);
+
+function dec(s) {
+    return parseInt(s);
+}
+noInline(dec);
+
+const hugeHex = "f".repeat(400);
+
+for (let i = 0; i < testLoopCount; ++i) {
+    let v = hex("80000000");
+    if (v !== 2147483648)
+        throw "FAILED: parseInt('80000000', 16) === " + v + " at iteration " + i;
+    v = hex("ffffffff");
+    if (v !== 4294967295)
+        throw "FAILED: parseInt('ffffffff', 16) === " + v + " at iteration " + i;
+    v = hex("7fffffff");
+    if (v !== 2147483647)
+        throw "FAILED: parseInt('7fffffff', 16) === " + v + " at iteration " + i;
+    v = hex("-80000001");
+    if (v !== -2147483649)
+        throw "FAILED: parseInt('-80000001', 16) === " + v + " at iteration " + i;
+    v = dec("2147483648");
+    if (v !== 2147483648)
+        throw "FAILED: parseInt('2147483648') === " + v + " at iteration " + i;
+    v = hex(hugeHex); // overflows to Infinity
+    if (v !== Infinity)
+        throw "FAILED: parseInt('f'.repeat(400), 16) === " + v + " at iteration " + i;
+}
diff --git a/JSTests/stress/switch-imm-scrutinee-above-int32.js b/JSTests/stress/switch-imm-scrutinee-above-int32.js
new file mode 100644
index 0000000000000..2ba88284ee4eb
--- /dev/null
+++ b/JSTests/stress/switch-imm-scrutinee-above-int32.js
@@ -0,0 +1,56 @@
+// A double scrutinee outside int32 range must never match an immediate
+// switch case. slow_path_switch_imm used to do static_cast<int32_t>(value)
+// — undefined behavior for out-of-range doubles — before the range check;
+// a UB-exploiting optimizer could then fold the check away and match the
+// case whose label equals the wrapped/saturated conversion result.
+
+function bigSwitch(x) {
+    switch (x) {
+    case -2147483648:
+        return "int32-min";
+    case 2147483647:
+        return "int32-max";
+    case 0:
+        return "zero";
+    default:
+        return "default";
+    }
+}
+noInline(bigSwitch);
+
+function denseSwitch(x) {
+    // Dense enough for a jump table (SwitchType::Immediate).
+    switch (x) {
+    case -2147483648: return 0;
+    case -2147483647: return 1;
+    case -2147483646: return 2;
+    case -2147483645: return 3;
+    case -2147483644: return 4;
+    case -2147483643: return 5;
+    case -2147483642: return 6;
+    case -2147483641: return 7;
+    default: return -1;
+    }
+}
+noInline(denseSwitch);
+
+for (let i = 0; i < testLoopCount; ++i) {
+    let r = bigSwitch(2147483648); // 2^31, truncates to INT32_MIN on x86
+    if (r !== "default")
+        throw "FAILED: bigSwitch(2^31) === " + r + " at iteration " + i;
+    r = bigSwitch(4294967296); // 2^32, truncates to 0 via modular wrap
+    if (r !== "default")
+        throw "FAILED: bigSwitch(2^32) === " + r + " at iteration " + i;
+    r = bigSwitch(Infinity);
+    if (r !== "default")
+        throw "FAILED: bigSwitch(Infinity) === " + r + " at iteration " + i;
+    r = bigSwitch(-2147483648);
+    if (r !== "int32-min")
+        throw "FAILED: bigSwitch(-2^31) === " + r + " at iteration " + i;
+    r = denseSwitch(2147483648);
+    if (r !== -1)
+        throw "FAILED: denseSwitch(2^31) === " + r + " at iteration " + i;
+    r = denseSwitch(-2147483648);
+    if (r !== 0)
+        throw "FAILED: denseSwitch(-2^31) === " + r + " at iteration " + i;
+}