Introduce CPUID

This commit introduces and uses cpuid information to pass the
proper llc `mcpu` flag.

Author: nicolasvasilache

tc/core/flags.cc

@@ -59,7 +59,7 @@ DEFINE_bool(llvm_dump_after_opt, false, "Print IR after optimization");
 DEFINE_bool(llvm_dump_asm, false, "Print asm");
 DEFINE_string(
     llvm_dump_asm_options,
-    "-march=x86-64 -mcpu=broadwell -filetype=asm",
+    "-filetype=asm",
     "Options used when dumping asm");
 
 DEFINE_uint32(

tc/core/polyhedral/codegen_llvm.cc

@@ -42,6 +42,7 @@
 #include "tc/core/polyhedral/schedule_isl_conversion.h"
 #include "tc/core/polyhedral/scop.h"
 #include "tc/core/scope_guard.h"
+#include "tc/core/utils/cpu.h"
 #include "tc/core/utils/system.h"
 #include "tc/external/isl.h"
 #include "tc/tc_config.h"
@@ -661,7 +662,7 @@ std::unique_ptr<llvm::Module> emitLLVMKernel(
     }
     utils::checkedSystemCall(
         std::string(TC_STRINGIFY(TC_LLVM_BIN_DIR)) + "/llc",
-        {FLAGS_llvm_dump_asm_options, optFile, std::string("-o ") + asmFile});
+        {FLAGS_llvm_dump_asm_options, utils::CPUID::llcFlags(), optFile, std::string("-o ") + asmFile});
     {
       std::ifstream is(asmFile);
       std::string str(

tc/core/utils/cpu.h

@@ -0,0 +1,140 @@
+/**
+ * Copyright (c) 2017-present, Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#pragma once
+
+#include <cpuid.h>
+
+#include "tc/core/flags.h"
+#include "tc/core/utils/cpu.h"
+
+namespace tc {
+namespace utils {
+
+#define INTEL_ebx 0x756e6547
+#define INTEL_ecx 0x6c65746e
+#define INTEL_edx 0x49656e69
+
+/**
+ * We start with a reasonable subset of the processors listed in the result
+ * of running the command:
+ *    llvm-as < /dev/null | llc -march=x86-64 -mcpu=help
+ */
+struct CPUID {
+ public:
+  CPUID() : eax(0), ebx(0), ecx(0), edx(0) {
+    __get_cpuid(1, &eax, &ebx, &ecx, &edx);
+  }
+
+  static bool isIntel() {
+    unsigned int a, b, c, d;
+    __get_cpuid(0, &a, &b, &c, &d);
+    return b == INTEL_ebx && c == INTEL_ecx && d == INTEL_edx;
+  }
+
+  using Stepping = unsigned char;
+  using Model = unsigned char;
+  using Family = unsigned char;
+  using ProcessorType = unsigned char;
+  using ExtendedModel = unsigned char;
+  using ExtendedFamily = unsigned short;
+  using FullModel = std::tuple<Model, ExtendedModel>;
+
+  struct LessCmp {
+    bool operator()(const FullModel& a, const FullModel& b) const {
+      return std::get<0>(a) < std::get<0>(b) && std::get<1>(a) < std::get<1>(b);
+    }
+  };
+  static const std::map<FullModel, std::string, LessCmp>&
+  intelFamily6ExtendedFamily0() {
+    static std::map<FullModel, std::string, LessCmp> map{
+        {FullModel(0xD, 0x3), "broadwell"},
+        {FullModel(0x7, 0x4), "broadwell"},
+        {FullModel(0x6, 0x6), "cannonlake"},
+        {FullModel(0xC, 0x3), "haswell"},
+        {FullModel(0xF, 0x3), "haswell"},
+        {FullModel(0x5, 0x4), "haswell"},
+        {FullModel(0x6, 0x4), "haswell"},
+        {FullModel(0xA, 0x3), "ivybridge"},
+        {FullModel(0xE, 0x3), "ivybridge"},
+        {FullModel(0xA, 0x2), "sandybridge"},
+        {FullModel(0xD, 0x2), "sandybridge"},
+        {FullModel(0xE, 0x4), "skylake"},
+        {FullModel(0xE, 0x5), "skylake"},
+        {FullModel(0x5, 0x5), "skylake-avx512"},
+        {FullModel(0x5, 0x2), "westmere"},
+        {FullModel(0xC, 0x2), "westmere"},
+        {FullModel(0xF, 0x2), "westmere"},
+    };
+    return map;
+  };
+
+  static std::tuple<
+      Stepping,
+      Model,
+      Family,
+      ProcessorType,
+      ExtendedModel,
+      ExtendedFamily>
+  parseCPU() {
+    CPUID id;
+    return std::make_tuple(
+        static_cast<Stepping>(id.eax & 0x0000000F), // 3:0
+        static_cast<Model>((id.eax >> 4) & 0x0000000F), // 7:4
+        static_cast<Family>((id.eax >> 8) & 0x0000000F), // 11:8
+        static_cast<ProcessorType>((id.eax >> 12) & 0x00000003), // 13:12
+        static_cast<ExtendedModel>((id.eax >> 16) & 0x0000000F), // 19:16
+        static_cast<ExtendedFamily>((id.eax >> 20) & 0x000000FF) // 27:20
+    );
+  }
+
+#define INTEL_FAMILY_6 0x6
+#define INTEL_EXTENDED_FAMILY_0 0x0
+  static std::string mcpu() {
+    if (FLAGS_mcpu.size() > 0) {
+      return FLAGS_mcpu;
+    }
+
+    TC_CHECK(CPUID::isIntel());
+    auto parsedCPU = CPUID::parseCPU();
+    auto model = std::get<1>(parsedCPU);
+    auto family = std::get<2>(parsedCPU);
+    auto extendedModel = std::get<4>(parsedCPU);
+    auto extendedFamily = std::get<5>(parsedCPU);
+    if (family == INTEL_FAMILY_6 && extendedFamily == INTEL_EXTENDED_FAMILY_0) {
+      if (intelFamily6ExtendedFamily0().count(FullModel(model, extendedModel)) >
+          0) {
+        return intelFamily6ExtendedFamily0().at(
+            FullModel(model, extendedModel));
+      }
+      return "x86-64";
+    }
+    TC_CHECK(false) << "Unsupported family/model/extendedmodel: " << family
+                    << "/" << model << "/" << extendedModel;
+    return "";
+  }
+
+  static std::string llcFlags() {
+    return std::string("-march=x86-64 -mcpu=") + CPUID::mcpu();
+  }
+
+ public:
+  unsigned int eax;
+  unsigned int ebx;
+  unsigned int ecx;
+  unsigned int edx;
+};
+} // namespace utils
+} // namespace tc