ARM: Enable the subnormal floats on QNX.

src/platform-qnx.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 89 matching lines @@
 #else
 #error "Your version of GCC does not report the FP ABI compiled for."          \
        "Please report it on this issue"                                        \
        "http://code.google.com/p/v8/issues/detail?id=2140"
 
 #endif
 #endif
 #undef GCC_VERSION
 }
 
+
+void OS::ArmEnableSubnormalFloat() {
+  // Clear the ARM_VFP_FPSCR_FZ flag in the FPSCR register.
+  uint32_t fpscr;
+  asm volatile("vmrs %0, fpscr" : "=r"(fpscr));
+  fpscr &= ~0x01000000u;
+  asm volatile("vmsr fpscr, %0" : : "r"(fpscr));

[Sven Panne, 2014/01/07 09:48:49]

I think a single parameter-less asm with 3 instructions would be more readable
than this asm/C++/asm dance.

+}
+
+struct QnxArmStaticInitializer {
+  QnxArmStaticInitializer() {
+    OS::ArmEnableSubnormalFloat();
+  }
+} qnx_arm_static_initializer;

[Sven Panne, 2014/01/07 09:48:49]

No new static initializers, please, use V8::InitializeOncePerProcessImpl when
really needed.

+
 #endif  // __arm__
 
 
 const char* OS::LocalTimezone(double time) {
   if (std::isnan(time)) return "";
   time_t tv = static_cast<time_t>(std::floor(time/msPerSecond));
   struct tm* t = localtime(&tv);
   if (NULL == t) return "";
   return t->tm_zone;
 }
@@ skipping 272 matching lines @@
 bool VirtualMemory::ReleaseRegion(void* base, size_t size) {
   return munmap(base, size) == 0;
 }
 
 
 bool VirtualMemory::HasLazyCommits() {
   return false;
 }
 
 } }  // namespace v8::internal