1 files changed, 123 insertions, 1 deletions

diff --git a/runtime/common_test.h b/runtime/common_test.h
index 673a03b35..79fa68039 100644
--- a/runtime/common_test.h
+++ b/runtime/common_test.h
@@ -22,6 +22,7 @@
 #include <sys/mman.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <fstream>
 
 #include "../../external/icu4c/common/unicode/uvernum.h"
 #include "base/macros.h"
@@ -152,6 +153,113 @@ class ScratchFile {
   UniquePtr<File> file_;
 };
 
+#if defined(__arm__)
+
+
+#include <signal.h>
+#include <asm/sigcontext.h>
+#include <asm/ucontext.h>
+
+
+// A signal handler called when have an illegal instruction.  We record the fact in
+// a global boolean and then increment the PC in the signal context to return to
+// the next instruction.  We know the instruction is an sdiv (4 bytes long).
+static void baddivideinst(int signo, siginfo *si, void *data) {
+  (void)signo;
+  (void)si;
+  struct ucontext *uc = (struct ucontext *)data;
+  struct sigcontext *sc = &uc->uc_mcontext;
+  sc->arm_r0 = 0;     // set R0 to #0 to signal error
+  sc->arm_pc += 4;    // skip offending instruction
+}
+
+// This is in arch/arm/arm_sdiv.S.  It does the following:
+// mov r1,#1
+// sdiv r0,r1,r1
+// bx lr
+//
+// the result will be the value 1 if sdiv is supported.  If it is not supported
+// a SIGILL signal will be raised and the signal handler (baddivideinst) called.
+// The signal handler sets r0 to #0 and then increments pc beyond the failed instruction.
+// Thus if the instruction is not supported, the result of this function will be #0
+
+extern "C" bool CheckForARMSDIVInstruction();
+
+static InstructionSetFeatures GuessInstructionFeatures() {
+  InstructionSetFeatures f;
+
+  // Uncomment this for processing of /proc/cpuinfo.
+  if (false) {
+    // Look in /proc/cpuinfo for features we need.  Only use this when we can guarantee that
+    // the kernel puts the appropriate feature flags in here.  Sometimes it doesn't.
+    std::ifstream in("/proc/cpuinfo");
+    if (in) {
+      while (!in.eof()) {
+        std::string line;
+        std::getline(in, line);
+        if (!in.eof()) {
+          if (line.find("Features") != std::string::npos) {
+            if (line.find("idivt") != std::string::npos) {
+              f.SetHasDivideInstruction(true);
+            }
+          }
+        }
+        in.close();
+      }
+    } else {
+      LOG(INFO) << "Failed to open /proc/cpuinfo";
+    }
+  }
+
+  // See if have a sdiv instruction.  Register a signal handler and try to execute
+  // an sdiv instruction.  If we get a SIGILL then it's not supported.  We can't use
+  // the /proc/cpuinfo method for this because Krait devices don't always put the idivt
+  // feature in the list.
+  struct sigaction sa, osa;
+  sa.sa_flags = SA_ONSTACK | SA_RESTART | SA_SIGINFO;
+  sa.sa_sigaction = baddivideinst;
+  sigaction(SIGILL, &sa, &osa);
+
+  if (CheckForARMSDIVInstruction()) {
+    f.SetHasDivideInstruction(true);
+  }
+
+  // Restore the signal handler.
+  sigaction(SIGILL, &osa, NULL);
+
+  // Other feature guesses in here.
+  return f;
+}
+
+#endif
+
+// Given a set of instruction features from the build, parse it.  The
+// input 'str' is a comma separated list of feature names.  Parse it and
+// return the InstructionSetFeatures object.
+static InstructionSetFeatures ParseFeatureList(std::string str) {
+  LOG(INFO) << "Parsing features " << str;
+  InstructionSetFeatures result;
+  typedef std::vector<std::string> FeatureList;
+  FeatureList features;
+  Split(str, ',', features);
+  for (FeatureList::iterator i = features.begin(); i != features.end(); i++) {
+    std::string feature = Trim(*i);
+    if (feature == "default") {
+      // Nothing to do.
+    } else if (feature == "div") {
+      // Supports divide instruction.
+      result.SetHasDivideInstruction(true);
+    } else if (feature == "nodiv") {
+      // Turn off support for divide instruction.
+      result.SetHasDivideInstruction(false);
+    } else {
+      LOG(FATAL) << "Unknown instruction set feature: '" << feature << "'";
+    }
+  }
+  // Others...
+  return result;
+}
+
 class CommonTest : public testing::Test {
  public:
   static void MakeExecutable(const mirror::ByteArray* code_array) {
@@ -314,8 +422,22 @@ class CommonTest : public testing::Test {
       class_linker_ = runtime_->GetClassLinker();
 
       InstructionSet instruction_set = kNone;
+
+      // take the default set of instruction features from the build if present
+      InstructionSetFeatures instruction_set_features =
+#ifdef ART_DEFAULT_INSTRUCTION_SET_FEATURES
+        ParseFeatureList(STRINGIFY(ART_DEFAULT_INSTRUCTION_SET_FEATURES));
+#else
+        ParseFeatureList("default");
+#endif
+
 #if defined(__arm__)
       instruction_set = kThumb2;
+      InstructionSetFeatures runtime_features = GuessInstructionFeatures();
+
+      // for ARM, do a runtime check to make sure that the features we are passed from
+      // the build match the features we actually determine at runtime.
+      ASSERT_EQ(instruction_set_features, runtime_features);
 #elif defined(__mips__)
       instruction_set = kMips;
 #elif defined(__i386__)
@@ -338,6 +460,7 @@ class CommonTest : public testing::Test {
       }
       class_linker_->FixupDexCaches(runtime_->GetResolutionMethod());
       compiler_driver_.reset(new CompilerDriver(compiler_backend, instruction_set,
+                                                instruction_set_features,
                                                 true, new CompilerDriver::DescriptorSet,
                                                 2, true));
     }
@@ -568,7 +691,6 @@ class CheckJniAbortCatcher {
 #else
 #define TEST_DISABLED_FOR_PORTABLE()
 #endif
-
 }  // namespace art
 
 namespace std {