ARM: Enable the subnormal floats on QNX.

src/platform.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This module contains the platform-specific code. This make the rest of the
 // code less dependent on operating system, compilers and runtime libraries.
 // This module does specifically not deal with differences between different
 // processor architecture.
 // The platform classes have the same definition for all platforms. The
 // implementation for a particular platform is put in platform_<os>.cc.
@@ skipping 279 matching lines @@
   static double nan_value();
 
   // Support runtime detection of whether the hard float option of the
   // EABI is used.
   static bool ArmUsingHardFloat();
 
   // Returns the activation frame alignment constraint or zero if
   // the platform doesn't care. Guaranteed to be a power of two.
   static int ActivationFrameAlignment();
 
+  // Perform the per-thread setup necessary for specific OSes and CPUs.
+  static void PerformPerThreadSetup() {
+#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:
   static const int msPerSecond = 1000;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(OS);
 };
 
 // Represents and controls an area of reserved memory.
 // Control of the reserved memory can be assigned to another VirtualMemory
@@ skipping 193 matching lines @@
   char name_[kMaxThreadNameLength];
   int stack_size_;
   Semaphore* start_semaphore_;
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PLATFORM_H_