Fix the CPU feature detection.

src/ia32/assembler-ia32.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 83 matching lines @@
   ASSERT(!initialized_);
   ASSERT(supported_ == 0);
 #ifdef DEBUG
   initialized_ = true;
 #endif
   if (Serializer::enabled()) {
     supported_ |= OS::CpuFeaturesImpliedByPlatform();
     return;  // No features if we might serialize.
   }
 
-  const int kBufferSize = 4 * KB;
-  VirtualMemory* memory = new VirtualMemory(kBufferSize);
-  if (!memory->IsReserved()) {
-    delete memory;
-    return;
+  uint64_t probed_features = 0;
+  CPU cpu;
+  if (cpu.has_sse41()) {
+    probed_features |= static_cast<uint64_t>(1) << SSE4_1;
   }
-  ASSERT(memory->size() >= static_cast<size_t>(kBufferSize));
-  if (!memory->Commit(memory->address(), kBufferSize, true/*executable*/)) {
-    delete memory;
-    return;
+  if (cpu.has_sse3()) {
+    probed_features |= static_cast<uint64_t>(1) << SSE3;
+  }
+  if (cpu.has_sse2()) {
+    probed_features |= static_cast<uint64_t>(1) << SSE2;
+  }
+  if (cpu.has_cmov()) {
+    probed_features |= static_cast<uint64_t>(1) << CMOV;
   }
 
-  Assembler assm(NULL, memory->address(), kBufferSize);
-  Label cpuid, done;
-#define __ assm.
-  // Save old esp, since we are going to modify the stack.
-  __ push(ebp);
-  __ pushfd();
-  __ push(ecx);
-  __ push(ebx);
-  __ mov(ebp, esp);
+  // SAHF must be available in compat/legacy mode.
+  ASSERT(cpu.has_sahf());
+  probed_features |= static_cast<uint64_t>(1) << SAHF;
 
-  // If we can modify bit 21 of the EFLAGS register, then CPUID is supported.
-  __ pushfd();
-  __ pop(eax);
-  __ mov(edx, eax);
-  __ xor_(eax, 0x200000);  // Flip bit 21.
-  __ push(eax);
-  __ popfd();
-  __ pushfd();
-  __ pop(eax);
-  __ xor_(eax, edx);  // Different if CPUID is supported.
-  __ j(not_zero, &cpuid);
-
-  // CPUID not supported. Clear the supported features in edx:eax.
-  __ xor_(eax, eax);
-  __ xor_(edx, edx);
-  __ jmp(&done);
-
-  // Invoke CPUID with 1 in eax to get feature information in
-  // ecx:edx. Temporarily enable CPUID support because we know it's
-  // safe here.
-  __ bind(&cpuid);
-  __ mov(eax, 1);
-  supported_ = (1 << CPUID);
-  { CpuFeatureScope fscope(&assm, CPUID);
-    __ cpuid();
-  }
-  supported_ = 0;
-
-  // Move the result from ecx:edx to edx:eax and make sure to mark the
-  // CPUID feature as supported.
-  __ mov(eax, edx);
-  __ or_(eax, 1 << CPUID);
-  __ mov(edx, ecx);
-
-  // Done.
-  __ bind(&done);
-  __ mov(esp, ebp);
-  __ pop(ebx);
-  __ pop(ecx);
-  __ popfd();
-  __ pop(ebp);
-  __ ret(0);
-#undef __
-
-  typedef uint64_t (*F0)();
-  F0 probe = FUNCTION_CAST<F0>(reinterpret_cast<Address>(memory->address()));
-  uint64_t probed_features = probe();
   uint64_t platform_features = OS::CpuFeaturesImpliedByPlatform();
   supported_ = probed_features | platform_features;
   found_by_runtime_probing_only_ = probed_features & ~platform_features;
-
-  delete memory;
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of Displacement
 
 void Displacement::init(Label* L, Type type) {
   ASSERT(!L->is_bound());
   int next = 0;
   if (L->is_linked()) {
@@ skipping 279 matching lines @@
   }
 }
 
 
 void Assembler::CodeTargetAlign() {
   Align(16);  // Preferred alignment of jump targets on ia32.
 }
 
 
 void Assembler::cpuid() {
-  ASSERT(IsEnabled(CPUID));
   EnsureSpace ensure_space(this);
   EMIT(0x0F);
   EMIT(0xA2);
 }
 
 
 void Assembler::pushad() {
   EnsureSpace ensure_space(this);
   EMIT(0x60);
 }
@@ skipping 2219 matching lines @@
     fprintf(coverage_log, "%s\n", file_line);
     fflush(coverage_log);
   }
 }
 
 #endif
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32