Refactors CPU feature detection.

runtime/vm/cpu_ia32.cc

Index: runtime/vm/cpu_ia32.cc
===================================================================
--- runtime/vm/cpu_ia32.cc	(revision 31402)
+++ runtime/vm/cpu_ia32.cc	(working copy)
@@ -3,18 +3,21 @@
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
-
 #if defined(TARGET_ARCH_IA32)
 
 #include "vm/cpu.h"
 
+#include "vm/assembler.h"
 #include "vm/constants_ia32.h"
+#include "vm/cpuinfo.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 
 namespace dart {
 
+DEFINE_FLAG(bool, use_sse41, true, "Use SSE 4.1 if available");
+
 void CPU::FlushICache(uword start, uword size) {
   // Nothing to be done here.
 }
@@ -24,6 +27,69 @@
   return "ia32";
 }
 
+
+bool CPUFeatures::sse2_supported_ = false;
+bool CPUFeatures::sse4_1_supported_ = false;
+char CPUFeatures::hardware_[HARDWARE_LEN] = {0};
+#ifdef DEBUG
+bool CPUFeatures::initialized_ = false;
+#endif
+
+
+bool CPUFeatures::sse2_supported() {
+  DEBUG_ASSERT(initialized_);
+  return sse2_supported_;
+}
+
+
+bool CPUFeatures::sse4_1_supported() {
+  DEBUG_ASSERT(initialized_);
+  return sse4_1_supported_ && FLAG_use_sse41;
+}
+
+
+char* CPUFeatures::hardware() {
+  DEBUG_ASSERT(initialized_);
+  return hardware_;
+}
+
+
+#define __ assembler.
+
+void CPUFeatures::InitOnce() {
+  Assembler assembler;
+  __ pushl(EBP);
+  __ pushl(EBX);
+  __ movl(EBP, ESP);
+  // Get feature information in ECX:EDX and return it in EDX:EAX.
+  __ movl(EAX, Immediate(1));
+  __ cpuid();
+  __ movl(EAX, EDX);
+  __ movl(EDX, ECX);
+  __ movl(ESP, EBP);
+  __ popl(EBX);
+  __ popl(EBP);
+  __ ret();
+
+  const Code& code =
+      Code::Handle(Code::FinalizeCode("DetectCPUFeatures", &assembler));
+  Instructions& instructions = Instructions::Handle(code.instructions());
+  typedef uint64_t (*DetectCPUFeatures)();
+  uint64_t features =
+      reinterpret_cast<DetectCPUFeatures>(instructions.EntryPoint())();
+  sse2_supported_ = (features & kSSE2BitMask) != 0;
+  sse4_1_supported_ = (features & kSSE4_1BitMask) != 0;
+
+  CpuInfo::Read();
+  CpuInfo::GetCpuModel(hardware_, HARDWARE_LEN);
+
+#ifdef DEBUG
+  initialized_ = true;
+#endif
+}
+
+#undef __
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32