Add detection LZCNT (#254)

Fixes #253

include/cpuinfo_x86.h

@@ -97,6 +97,7 @@ typedef struct {
   int dca : 1;
   int ss : 1;
   int adx : 1;
+  int lzcnt : 1;  // Note: this flag is called ABM for AMD, LZCNT for Intel.
   // Make sure to update X86FeaturesEnum below if you add a field here.
 } X86Features;
 
@@ -247,6 +248,7 @@ typedef enum {
   X86_DCA,
   X86_SS,
   X86_ADX,
+  X86_LZCNT,
   X86_LAST_,
 } X86FeaturesEnum;
 

src/impl_x86__base_implementation.inl

@@ -254,6 +254,7 @@ static void ParseCpuId(const Leaves* leaves, X86Info* info,
   const Leaf leaf_1 = leaves->leaf_1;
   const Leaf leaf_7 = leaves->leaf_7;
   const Leaf leaf_7_1 = leaves->leaf_7_1;
+  const Leaf leaf_80000001 = leaves->leaf_80000001;
 
   const bool have_xsave = IsBitSet(leaf_1.ecx, 26);
   const bool have_osxsave = IsBitSet(leaf_1.ecx, 27);
@@ -312,6 +313,7 @@ static void ParseCpuId(const Leaves* leaves, X86Info* info,
   features->vaes = IsBitSet(leaf_7.ecx, 9);
   features->vpclmulqdq = IsBitSet(leaf_7.ecx, 10);
   features->adx = IsBitSet(leaf_7.ebx, 19);
+  features->lzcnt = IsBitSet(leaf_80000001.ecx, 5);
 
   /////////////////////////////////////////////////////////////////////////////
   // The following section is devoted to Vector Extensions.
@@ -1755,7 +1757,8 @@ CacheInfo GetX86CacheInfo(void) {
   LINE(X86_RDRND, rdrnd, , , )                             \
   LINE(X86_DCA, dca, , , )                                 \
   LINE(X86_SS, ss, , , )                                   \
-  LINE(X86_ADX, adx, , , )
+  LINE(X86_ADX, adx, , , )                                 \
+  LINE(X86_LZCNT, lzcnt, , , )
 #define INTROSPECTION_PREFIX X86
 #define INTROSPECTION_ENUM_PREFIX X86
 #include "define_introspection.inl"

test/cpuinfo_x86_test.cc

@@ -540,6 +540,27 @@ TEST_F(CpuidX86Test, AMD_K15_STREAMROLLER_GODAVARI) {
             X86Microarchitecture::AMD_STREAMROLLER);
 }
 
+// http://users.atw.hu/instlatx64/AuthenticAMD/AuthenticAMD0600F12_K15_Zambezi8C_CPUID.txt
+TEST_F(CpuidX86Test, AMD_K15_BULLDOZER_ZAMBEZI_ABM) {
+  cpu().SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000D, 0x68747541, 0x444D4163, 0x69746E65}},
+      {{0x00000001, 0}, Leaf{0x00600F12, 0x00080800, 0x1E98220B, 0x178BFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x8000001E, 0x68747541, 0x444D4163, 0x69746E65}},
+      {{0x80000001, 0}, Leaf{0x00600F12, 0x10000000, 0x01C9BFFF, 0x2FD3FBFF}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "AuthenticAMD");
+  EXPECT_EQ(info.family, 0x15);
+  EXPECT_EQ(info.model, 0x01);
+
+  EXPECT_EQ(GetX86Microarchitecture(&info),
+            X86Microarchitecture::AMD_BULLDOZER);
+
+  EXPECT_TRUE(info.features.lzcnt);
+}
+
 // http://users.atw.hu/instlatx64/AuthenticAMD/AuthenticAMD0700F01_K16_Kabini_CPUID.txt
 TEST_F(CpuidX86Test, AMD_K16_JAGUAR_KABINI) {
   cpu().SetLeaves({
@@ -1110,8 +1131,7 @@ TEST_F(CpuidX86Test, INTEL_CML_U) {
   EXPECT_EQ(info.family, 0x06);
   EXPECT_EQ(info.model, 0x8E);
   EXPECT_EQ(info.stepping, 0x0C);
-  EXPECT_EQ(GetX86Microarchitecture(&info),
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::INTEL_CML);
-            X86Microarchitecture::INTEL_CML);
 }
 
 // http://users.atw.hu/instlatx64/GenuineIntel/GenuineIntel00A0652_CometLake_CPUID1.txt
@@ -1125,8 +1145,26 @@ TEST_F(CpuidX86Test, INTEL_CML_H) {
   EXPECT_STREQ(info.vendor, "GenuineIntel");
   EXPECT_EQ(info.family, 0x06);
   EXPECT_EQ(info.model, 0xA5);
-  EXPECT_EQ(GetX86Microarchitecture(&info),
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::INTEL_CML);
-            X86Microarchitecture::INTEL_CML);
+}
+
+// http://users.atw.hu/instlatx64/GenuineIntel/GenuineIntel00306F2_HaswellEP2_CPUID.txt
+TEST_F(CpuidX86Test, INTEL_HASWELL_LZCNT) {
+  cpu().SetLeaves({
+      {{0x00000000, 0}, Leaf{0x0000000F, 0x756E6547, 0x6C65746E, 0x49656E69}},
+      {{0x00000001, 0}, Leaf{0x000306F2, 0x00200800, 0x7FFEFBFF, 0xBFEBFBFF}},
+      {{0x00000007, 0}, Leaf{0x00000000, 0x000037AB, 0x00000000, 0x00000000}},
+      {{0x80000000, 0}, Leaf{0x80000008, 0x00000000, 0x00000000, 0x00000000}},
+      {{0x80000001, 0}, Leaf{0x00000000, 0x00000000, 0x00000021, 0x2C100000}},
+  });
+  const auto info = GetX86Info();
+
+  EXPECT_STREQ(info.vendor, "GenuineIntel");
+  EXPECT_EQ(info.family, 0x06);
+  EXPECT_EQ(info.model, 0x3F);
+  EXPECT_EQ(GetX86Microarchitecture(&info), X86Microarchitecture::INTEL_HSW);
+
+  EXPECT_TRUE(info.features.lzcnt);
 }
 
 // https://github.com/google/cpu_features/issues/200