[AArch64] Add Exynos to host detection

Differential revision: https://reviews.llvm.org/D40985

llvm-svn: 320195

llvm/lib/Support/Host.cpp

@@ -216,6 +216,37 @@ StringRef sys::detail::getHostCPUNameForARM(
             .Case("0xc01", "saphira")
             .Default("generic");
 
+  if (Implementer == "0x53") { // Samsung Electronics Co., Ltd.
+    // The Exynos chips have a convoluted ID scheme that doesn't seem to follow
+    // any predictive pattern across variants and parts.
+    unsigned Variant = 0, Part = 0;
+
+    // Look for the CPU variant line, whose value is a 1 digit hexadecimal
+    // number, corresponding to the Variant bits in the CP15/C0 register.
+    for (auto I : Lines)
+      if (I.consume_front("CPU variant"))
+        I.ltrim("\t :").getAsInteger(0, Variant);
+
+    // Look for the CPU part line, whose value is a 3 digit hexadecimal
+    // number, corresponding to the PartNum bits in the CP15/C0 register.
+    for (auto I : Lines)
+      if (I.consume_front("CPU part"))
+        I.ltrim("\t :").getAsInteger(0, Part);
+
+    unsigned Exynos = (Variant << 12) | Part;
+    switch (Exynos) {
+    default:
+      // Default by falling through to Exynos M1.
+      LLVM_FALLTHROUGH;
+
+    case 0x1001:
+      return "exynos-m1";
+
+    case 0x4001:
+      return "exynos-m2";
+    }
+  }
+
   return "generic";
 }
 

llvm/unittests/Support/Host.cpp

@@ -139,6 +139,37 @@ Hardware        : Qualcomm Technologies, Inc MSM8992
 
   EXPECT_EQ(sys::detail::getHostCPUNameForARM(MSM8992ProcCpuInfo),
             "cortex-a53");
+
+  // Exynos big.LITTLE weirdness
+  const std::string ExynosProcCpuInfo = R"(
+processor       : 0
+Features        : fp asimd evtstrm aes pmull sha1 sha2 crc32
+CPU implementer : 0x41
+CPU architecture: 8
+CPU variant     : 0x0
+CPU part        : 0xd03
+
+processor       : 1
+Features        : fp asimd evtstrm aes pmull sha1 sha2 crc32
+CPU implementer : 0x53
+CPU architecture: 8
+)";
+
+  // Verify default for Exynos.
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM(ExynosProcCpuInfo +
+                                              "CPU variant     : 0xc\n"
+                                              "CPU part        : 0xafe"),
+            "exynos-m1");
+  // Verify Exynos M1.
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM(ExynosProcCpuInfo +
+                                              "CPU variant     : 0x1\n"
+                                              "CPU part        : 0x001"),
+            "exynos-m1");
+  // Verify Exynos M2.
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM(ExynosProcCpuInfo +
+                                              "CPU variant     : 0x4\n"
+                                              "CPU part        : 0x001"),
+            "exynos-m2");
 }
 
 #if defined(__APPLE__)