Reverts refactoring of CPU feature detection for

runtime/vm/assembler_x64.cc

Index: runtime/vm/assembler_x64.cc
===================================================================
--- runtime/vm/assembler_x64.cc	(revision 32559)
+++ runtime/vm/assembler_x64.cc	(working copy)
@@ -6,7 +6,6 @@
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
-#include "vm/cpu.h"
 #include "vm/heap.h"
 #include "vm/memory_region.h"
 #include "vm/runtime_entry.h"
@@ -16,9 +15,56 @@
 namespace dart {
 
 DEFINE_FLAG(bool, print_stop_message, true, "Print stop message.");
+DEFINE_FLAG(bool, use_sse41, true, "Use SSE 4.1 if available");
 DECLARE_FLAG(bool, inline_alloc);
 
 
+bool CPUFeatures::sse4_1_supported_ = false;
+#ifdef DEBUG
+bool CPUFeatures::initialized_ = false;
+#endif
+
+bool CPUFeatures::sse4_1_supported() {
+  DEBUG_ASSERT(initialized_);
+  return sse4_1_supported_ && FLAG_use_sse41;
+}
+
+
+#define __ assembler.
+
+void CPUFeatures::InitOnce() {
+  Assembler assembler;
+  __ pushq(RBP);
+  __ pushq(RBX);
+  __ movq(RBP, RSP);
+  // Get feature information in ECX:EDX and return it in RAX.
+  // Note that cpuid operates the same in 64-bit and 32-bit mode.
+  __ movq(RAX, Immediate(1));
+  __ cpuid();
+  __ movl(RAX, RCX);  // Zero extended.
+  __ shlq(RAX, Immediate(32));
+  __ movl(RCX, RDX);  // Zero extended.
+  __ orq(RAX, RCX);
+  __ movq(RSP, RBP);
+  __ popq(RBX);
+  __ popq(RBP);
+  __ 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())();
+  sse4_1_supported_ = (features & kSSE4_1BitMask) != 0;
+#ifdef DEBUG
+  initialized_ = true;
+#endif
+}
+
+#undef __
+
+
 Assembler::Assembler(bool use_far_branches)
     : buffer_(),
       object_pool_(GrowableObjectArray::Handle()),