Fix the CPU feature detection.

src/x64/assembler-x64.cc

 // Copyright 2012 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 45 matching lines @@
   ASSERT(supported_ == CpuFeatures::kDefaultCpuFeatures);
 #ifdef DEBUG
   initialized_ = true;
 #endif
   supported_ = kDefaultCpuFeatures;
   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;
   }
 
-  Assembler assm(NULL, memory->address(), kBufferSize);
-  Label cpuid, done;
-#define __ assm.
-  // Save old rsp, since we are going to modify the stack.
-  __ push(rbp);
-  __ pushfq();
-  __ push(rdi);
-  __ push(rcx);
-  __ push(rbx);
-  __ movq(rbp, rsp);
+  // SSE2 must be available on every x64 CPU.
+  ASSERT(cpu.has_sse2());
+  probed_features |= static_cast<uint64_t>(1) << SSE2;
 
-  // If we can modify bit 21 of the EFLAGS register, then CPUID is supported.
-  __ pushfq();
-  __ pop(rax);
-  __ movq(rdx, rax);
-  __ xor_(rax, Immediate(0x200000));  // Flip bit 21.
-  __ push(rax);
-  __ popfq();
-  __ pushfq();
-  __ pop(rax);
-  __ xor_(rax, rdx);  // Different if CPUID is supported.
-  __ j(not_zero, &cpuid);
+  // CMOD must be available on every x64 CPU.
+  ASSERT(cpu.has_cmov());
+  probed_features |= static_cast<uint64_t>(1) << CMOV;
 
-  // CPUID not supported. Clear the supported features in rax.
-  __ xor_(rax, rax);
-  __ jmp(&done);
+  // SAHF is not generally available in long mode.
+  if (cpu.has_sahf()) {
+    probed_features |= static_cast<uint64_t>(1) << SAHF;
+  }
 
-  // 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);
-  __ movl(rax, Immediate(1));
-  supported_ = kDefaultCpuFeatures | (1 << CPUID);
-  { CpuFeatureScope fscope(&assm, CPUID);
-    __ cpuid();
-    // Move the result from ecx:edx to rdi.
-    __ movl(rdi, rdx);  // Zero-extended to 64 bits.
-    __ shl(rcx, Immediate(32));
-    __ or_(rdi, rcx);
-
-    // Get the sahf supported flag, from CPUID(0x80000001)
-    __ movq(rax, 0x80000001, RelocInfo::NONE64);
-    __ cpuid();
-  }
-  supported_ = kDefaultCpuFeatures;
-
-  // Put the CPU flags in rax.
-  // rax = (rcx & 1) | (rdi & ~1) | (1 << CPUID).
-  __ movl(rax, Immediate(1));
-  __ and_(rcx, rax);  // Bit 0 is set if SAHF instruction supported.
-  __ not_(rax);
-  __ and_(rax, rdi);
-  __ or_(rax, rcx);
-  __ or_(rax, Immediate(1 << CPUID));
-
-  // Done.
-  __ bind(&done);
-  __ movq(rsp, rbp);
-  __ pop(rbx);
-  __ pop(rcx);
-  __ pop(rdi);
-  __ popfq();
-  __ pop(rbp);
-  __ 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 & ~kDefaultCpuFeatures & ~platform_features;
-
-  // CMOV must be available on an X64 CPU.
-  ASSERT(IsSupported(CPUID));
-  ASSERT(IsSupported(CMOV));
-
-  delete memory;
 }
 
 
 // -----------------------------------------------------------------------------
 // Implementation of RelocInfo
 
 // Patch the code at the current PC with a call to the target address.
 // Additional guard int3 instructions can be added if required.
 void RelocInfo::PatchCodeWithCall(Address target, int guard_bytes) {
   int code_size = Assembler::kCallSequenceLength + guard_bytes;
@@ skipping 812 matching lines @@
 
 void Assembler::cmpb_al(Immediate imm8) {
   ASSERT(is_int8(imm8.value_) || is_uint8(imm8.value_));
   EnsureSpace ensure_space(this);
   emit(0x3c);
   emit(imm8.value_);
 }
 
 
 void Assembler::cpuid() {
-  ASSERT(IsEnabled(CPUID));
   EnsureSpace ensure_space(this);
   emit(0x0F);
   emit(0xA2);
 }
 
 
 void Assembler::cqo() {
   EnsureSpace ensure_space(this);
   emit_rex_64();
   emit(0x99);
@@ skipping 2102 matching lines @@
 bool RelocInfo::IsCodedSpecially() {
   // The deserializer needs to know whether a pointer is specially coded.  Being
   // specially coded on x64 means that it is a relative 32 bit address, as used
   // by branch instructions.
   return (1 << rmode_) & kApplyMask;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64