From 5694f0b69cf527a674285fb20ce583c5a2c39f2f Mon Sep 17 00:00:00 2001
From: Yi Kong <yikong@google.com>
Date: Tue, 4 Apr 2017 19:06:04 +0000
Subject: [PATCH] Implement host CPU detection for AArch64

This shares detection logic with ARM(32), since AArch64 capable CPUs may
also run in 32-bit system mode.

We observe weird /proc/cpuinfo output for MSM8992 and MSM8994, where
they report all CPU cores as one single model, depending on which CPU
core the kernel is running on. As a workaround, we hardcode the known
CPU part name for these SoCs.

For big.LITTLE systems, this patch would only return the part name of
the first core (usually the little core). Proper support will be added
in a follow-up change.

Differential Revision: D31675

llvm-svn: 299458
---
 lib/Support/Host.cpp       | 36 ++++++++++++++++++++++++++++++++----
 unittests/Support/Host.cpp | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 4 deletions(-)

diff --git a/lib/Support/Host.cpp b/lib/Support/Host.cpp
index 54fbb558c43..8a02a86a574 100644
--- a/lib/Support/Host.cpp
+++ b/lib/Support/Host.cpp
@@ -149,18 +149,28 @@ StringRef sys::detail::getHostCPUNameForARM(
   // The cpuid register on arm is not accessible from user space. On Linux,
   // it is exposed through the /proc/cpuinfo file.
 
-  // Read 1024 bytes from /proc/cpuinfo, which should contain the CPU part line
+  // Read 32 lines from /proc/cpuinfo, which should contain the CPU part line
   // in all cases.
   SmallVector<StringRef, 32> Lines;
   ProcCpuinfoContent.split(Lines, "\n");
 
   // Look for the CPU implementer line.
   StringRef Implementer;
-  for (unsigned I = 0, E = Lines.size(); I != E; ++I)
+  StringRef Hardware;
+  for (unsigned I = 0, E = Lines.size(); I != E; ++I) {
     if (Lines[I].startswith("CPU implementer"))
       Implementer = Lines[I].substr(15).ltrim("\t :");
+    if (Lines[I].startswith("Hardware"))
+      Hardware = Lines[I].substr(8).ltrim("\t :");
+  }
+
+  if (Implementer == "0x41") { // ARM Ltd.
+    // MSM8992/8994 may give cpu part for the core that the kernel is running on,
+    // which is undeterministic and wrong. Always return cortex-a53 for these SoC.
+    if (Hardware.endswith("MSM8994") || Hardware.endswith("MSM8996"))
+      return "cortex-a53";
+
 
-  if (Implementer == "0x41") // ARM Ltd.
     // Look for the CPU part line.
     for (unsigned I = 0, E = Lines.size(); I != E; ++I)
       if (Lines[I].startswith("CPU part"))
@@ -179,6 +189,22 @@ StringRef sys::detail::getHostCPUNameForARM(
             .Case("0xc20", "cortex-m0")
             .Case("0xc23", "cortex-m3")
             .Case("0xc24", "cortex-m4")
+            .Case("0xd03", "cortex-a53")
+            .Case("0xd07", "cortex-a57")
+            .Case("0xd08", "cortex-a72")
+            .Case("0xd09", "cortex-a73")
+            .Default("generic");
+  }
+
+  if (Implementer == "0x50") // Applied Micro Circuits Corporation (APM).
+    // Look for the CPU part line.
+    for (unsigned I = 0, E = Lines.size(); I != E; ++I)
+      if (Lines[I].startswith("CPU part"))
+        // The CPU part is a 3 digit hexadecimal number with a 0x prefix. The
+        // values correspond to the "Part number" in the CP15/c0 register. The
+        // contents are specified in the various processor manuals.
+        return StringSwitch<const char *>(Lines[I].substr(8).ltrim("\t :"))
+            .Case("0x000", "xgene1")
             .Default("generic");
 
   if (Implementer == "0x51") // Qualcomm Technologies, Inc.
@@ -190,6 +216,8 @@ StringRef sys::detail::getHostCPUNameForARM(
         // contents are specified in the various processor manuals.
         return StringSwitch<const char *>(Lines[I].substr(8).ltrim("\t :"))
             .Case("0x06f", "krait") // APQ8064
+            .Case("0x201", "kryo")
+            .Case("0x205", "kryo")
             .Default("generic");
 
   return "generic";
@@ -1199,7 +1227,7 @@ StringRef sys::getHostCPUName() {
   const StringRef& Content = P ? P->getBuffer() : "";
   return detail::getHostCPUNameForPowerPC(Content);
 }
-#elif defined(__linux__) && defined(__arm__)
+#elif defined(__linux__) && (defined(__arm__) || defined(__aarch64__))
 StringRef sys::getHostCPUName() {
   std::unique_ptr<llvm::MemoryBuffer> P = getProcCpuinfoContent();
   const StringRef& Content = P ? P->getBuffer() : "";
diff --git a/unittests/Support/Host.cpp b/unittests/Support/Host.cpp
index 48f021e5427..fd53697793c 100644
--- a/unittests/Support/Host.cpp
+++ b/unittests/Support/Host.cpp
@@ -79,3 +79,38 @@ Serial          : 0000000000000000
                                               "CPU part        : 0x06f"),
             "krait");
 }
+
+TEST(getLinuxHostCPUName, AArch64) {
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM("CPU implementer : 0x41\n"
+                                              "CPU part        : 0xd03"),
+            "cortex-a53");
+  // Verify that both CPU implementer and CPU part are checked:
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM("CPU implementer : 0x40\n"
+                                              "CPU part        : 0xd03"),
+            "generic");
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM("CPU implementer : 0x51\n"
+                                              "CPU part        : 0x201"),
+            "kryo");
+
+  // MSM8992/4 weirdness
+  StringRef MSM8992ProcCpuInfo = R"(
+Processor       : AArch64 Processor rev 3 (aarch64)
+processor       : 0
+processor       : 1
+processor       : 2
+processor       : 3
+processor       : 4
+processor       : 5
+Features        : fp asimd evtstrm aes pmull sha1 sha2 crc32
+CPU implementer : 0x41
+CPU architecture: 8
+CPU variant     : 0x0
+CPU part        : 0xd03
+CPU revision    : 3
+
+Hardware        : Qualcomm Technologies, Inc MSM8992
+)";
+
+  EXPECT_EQ(sys::detail::getHostCPUNameForARM(MSM8992ProcCpuInfo),
+            "cortex-a53");
+}