MIPS/ARM: Fix benchmarks failures on simulator.

src/mips/simulator-mips.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
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 #include <stdlib.h>
 #include <limits.h>
+#include <fpu_control.h>
 #include <cmath>
 #include <cstdarg>
 #include "v8.h"
 
 #if V8_TARGET_ARCH_MIPS
 
 #include "cpu.h"
 #include "disasm.h"
 #include "assembler.h"
 #include "globals.h"    // Need the BitCast.
@@ skipping 835 matching lines @@
 
 void Simulator::Initialize(Isolate* isolate) {
   if (isolate->simulator_initialized()) return;
   isolate->set_simulator_initialized(true);
   ::v8::internal::ExternalReference::set_redirector(isolate,
                                                     &RedirectExternalReference);
 }
 
 
 Simulator::Simulator(Isolate* isolate) : isolate_(isolate) {
+  set_host_fp_precision();
+
   i_cache_ = isolate_->simulator_i_cache();
   if (i_cache_ == NULL) {
     i_cache_ = new v8::internal::HashMap(&ICacheMatch);
     isolate_->set_simulator_i_cache(i_cache_);
   }
   Initialize(isolate);
   // Set up simulator support first. Some of this information is needed to
   // setup the architecture state.
   stack_ = reinterpret_cast<char*>(malloc(stack_size_));
   pc_modified_ = false;
@@ skipping 2015 matching lines @@
 
 uintptr_t Simulator::PopAddress() {
   int current_sp = get_register(sp);
   uintptr_t* stack_slot = reinterpret_cast<uintptr_t*>(current_sp);
   uintptr_t address = *stack_slot;
   set_register(sp, current_sp + sizeof(uintptr_t));
   return address;
 }
 
 
+void Simulator::set_host_fp_precision() {
+#if !V8_HOST_ARCH_MIPS
+  // Set Intel x87 FPU mode to 64-bit double.
+  // The default FPU mode is extended (80-bit),
+  // which can lead to unexpected precision failures.
+  fpu_control_t cw;
+  _FPU_GETCW(cw);
+  cw &= ~_FPU_EXTENDED;
+  cw |= _FPU_DOUBLE;
+  _FPU_SETCW(cw);
+#endif
+}
+
+
 #undef UNSUPPORTED
 
 } }  // namespace v8::internal
 
 #endif  // USE_SIMULATOR
 
 #endif  // V8_TARGET_ARCH_MIPS