ART: Do a pre-pass for monitor_enter dex pc search

In case the method does not have any monitor_enter instructions,
it is unnecessary to run the full verifier. Speeds up stack dumps
and works around b/17514582.

Bug: 17514582
Change-Id: I5201bfbb9fb6cad49596b4c72e71983b58d9f20c

1 files changed, 21 insertions, 0 deletions

diff --git a/runtime/verifier/method_verifier.cc b/runtime/verifier/method_verifier.cc
index 467390662f..02aea1970f 100644
--- a/runtime/verifier/method_verifier.cc
+++ b/runtime/verifier/method_verifier.cc
@@ -379,10 +379,31 @@ void MethodVerifier::FindLocksAtDexPc(mirror::ArtMethod* m, uint32_t dex_pc,
   verifier.FindLocksAtDexPc();
 }
 
+static bool HasMonitorEnterInstructions(const DexFile::CodeItem* const code_item) {
+  const Instruction* inst = Instruction::At(code_item->insns_);
+
+  uint32_t insns_size = code_item->insns_size_in_code_units_;
+  for (uint32_t dex_pc = 0; dex_pc < insns_size;) {
+    if (inst->Opcode() == Instruction::MONITOR_ENTER) {
+      return true;
+    }
+
+    dex_pc += inst->SizeInCodeUnits();
+    inst = inst->Next();
+  }
+
+  return false;
+}
+
 void MethodVerifier::FindLocksAtDexPc() {
   CHECK(monitor_enter_dex_pcs_ != nullptr);
   CHECK(code_item_ != nullptr);  // This only makes sense for methods with code.
 
+  // Quick check whether there are any monitor_enter instructions at all.
+  if (!HasMonitorEnterInstructions(code_item_)) {
+    return;
+  }
+
   // Strictly speaking, we ought to be able to get away with doing a subset of the full method
   // verification. In practice, the phase we want relies on data structures set up by all the
   // earlier passes, so we just run the full method verification and bail out early when we've