ARM: Enable the subnormal floats on QNX.

src/platform.h

Index: src/platform.h
diff --git a/src/platform.h b/src/platform.h
index 51eefc10f802a7691a1ef4dcebf753eb87be2c5d..fedd30e1eef1192f41022006c20ba97aa9d55b3f 100644
--- a/src/platform.h
+++ b/src/platform.h
@@ -398,6 +398,20 @@ class OS {
   static const int kMinComplexMemCopy = 16 * kPointerSize;
 #endif  // V8_TARGET_ARCH_IA32
 
+  // Perform the per-thread setup necessary for specific OSes and CPUs.
+  static void PerThreadSetUp() {
+#if V8_OS_QNX && defined(V8_HOST_ARCH_ARM)
+    // Clear the ARM_VFP_FPSCR_FZ flag in the FPSCR register.
+    // This disables the flush-to-zero mode in the VFP, allowing
+    // the handling of subnormals.
+    asm volatile(
+        "vmrs r3, fpscr          \n\t"
+        "bic  r3, r3, 0x01000000 \n\t"
+        "vmsr fpscr, r3"
+        : : : "r3");
+#endif  // V8_OS_QNX && V8_HOST_ARCH_ARM
+  }
+
   static int GetCurrentProcessId();
 
  private: