Optimize shadow frame initialization during invoke.

This CL improves the initialization of the new shadow frame (callee) from the
current shadow frame (caller) following invoke format (non-range or range).

This also removes the use of Instruction::GetArgs for non-range invoke when we
can go the fast route (no use of shorty). This avoids decoding arguments into
the stack from the instruction and then read these arguments from the stack. We
now do both at once. Note the slow path (doing runtime checks) is not modified
since it should be rarely used.

Performance improved by 3% in average on our benchmarks. Good news it is more
important on benchmark doing lots of invokes:
- Dhrystone: +11%
- DeltaBlue: +7%
- CaffeineMark Method: +16%

Bug: 10668955
Change-Id: I5c230777b2388a78dca7b3a88189e007c1c2bb7a

1 files changed, 93 insertions, 57 deletions

diff --git a/runtime/interpreter/interpreter_common.cc b/runtime/interpreter/interpreter_common.cc
index 4992031..6f87a8f 100644
--- a/runtime/interpreter/interpreter_common.cc
+++ b/runtime/interpreter/interpreter_common.cc
@@ -24,6 +24,19 @@ static void UnstartedRuntimeInvoke(Thread* self, MethodHelper& mh,
                                    JValue* result, size_t arg_offset)
     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
+// Assign register 'src_reg' from shadow_frame to register 'dest_reg' into new_shadow_frame.
+static inline void AssignRegister(ShadowFrame& new_shadow_frame, const ShadowFrame& shadow_frame,
+                                  size_t dest_reg, size_t src_reg) {
+  // If both register locations contains the same value, the register probably holds a reference.
+  int32_t src_value = shadow_frame.GetVReg(src_reg);
+  mirror::Object* o = shadow_frame.GetVRegReference(src_reg);
+  if (src_value == reinterpret_cast<int32_t>(o)) {
+    new_shadow_frame.SetVRegReference(dest_reg, o);
+  } else {
+    new_shadow_frame.SetVReg(dest_reg, src_value);
+  }
+}
+
 template<bool is_range, bool do_assignability_check>
 bool DoCall(ArtMethod* method, Object* receiver, Thread* self, ShadowFrame& shadow_frame,
             const Instruction* inst, uint16_t inst_data, JValue* result) {
@@ -45,67 +58,90 @@ bool DoCall(ArtMethod* method, Object* receiver, Thread* self, ShadowFrame& shad
   ShadowFrame* new_shadow_frame(ShadowFrame::Create(num_regs, &shadow_frame, method, 0, memory));
 
   // Initialize new shadow frame.
-  size_t cur_reg = num_regs - num_ins;
-  size_t arg_offset = 0;
-  if (receiver != NULL) {
-    DCHECK(!method->IsStatic());
-    new_shadow_frame->SetVRegReference(cur_reg, receiver);
-    ++cur_reg;
-    ++arg_offset;
-  } else {
-    DCHECK(method->IsStatic());
-  }
-
-  const DexFile::TypeList* params;
+  const size_t first_dest_reg = num_regs - num_ins;
   if (do_assignability_check) {
-    params = mh.GetParameterTypeList();
-  }
-  const char* shorty = mh.GetShorty();
-  // TODO: find a cleaner way to separate non-range and range information.
-  uint32_t arg[5];  // only used in invoke-XXX.
-  uint32_t vregC;   // only used in invoke-XXX-range.
-  if (is_range) {
-    vregC = inst->VRegC_3rc();
-  } else {
-    inst->GetArgs(arg, inst_data);
-  }
-  for (size_t shorty_pos = 0; cur_reg < num_regs; ++shorty_pos, ++cur_reg, ++arg_offset) {
-    DCHECK_LT(shorty_pos + 1, mh.GetShortyLength());
-    size_t arg_pos = (is_range) ? vregC + arg_offset : arg[arg_offset];
-    switch (shorty[shorty_pos + 1]) {
-      case 'L': {
-        Object* o = shadow_frame.GetVRegReference(arg_pos);
-        if (do_assignability_check && o != NULL) {
-          Class* arg_type = mh.GetClassFromTypeIdx(params->GetTypeItem(shorty_pos).type_idx_);
-          if (arg_type == NULL) {
-            CHECK(self->IsExceptionPending());
-            return false;
-          }
-          if (!o->VerifierInstanceOf(arg_type)) {
-            // This should never happen.
-            self->ThrowNewExceptionF(self->GetCurrentLocationForThrow(),
-                                     "Ljava/lang/VirtualMachineError;",
-                                     "Invoking %s with bad arg %d, type '%s' not instance of '%s'",
-                                     mh.GetName(), shorty_pos,
-                                     ClassHelper(o->GetClass()).GetDescriptor(),
-                                     ClassHelper(arg_type).GetDescriptor());
-            return false;
+    // Slow path: we need to do runtime check on reference assignment. We need to load the shorty
+    // to get the exact type of each reference argument.
+    const DexFile::TypeList* params = mh.GetParameterTypeList();
+    const char* shorty = mh.GetShorty();
+
+    // Handle receiver apart since it's not part of the shorty.
+    size_t dest_reg = first_dest_reg;
+    size_t arg_offset = 0;
+    if (receiver != NULL) {
+      DCHECK(!method->IsStatic());
+      new_shadow_frame->SetVRegReference(dest_reg, receiver);
+      ++dest_reg;
+      ++arg_offset;
+    } else {
+      DCHECK(method->IsStatic());
+    }
+    // TODO: find a cleaner way to separate non-range and range information without duplicating code.
+    uint32_t arg[5];  // only used in invoke-XXX.
+    uint32_t vregC;   // only used in invoke-XXX-range.
+    if (is_range) {
+      vregC = inst->VRegC_3rc();
+    } else {
+      inst->GetArgs(arg, inst_data);
+    }
+    for (size_t shorty_pos = 0; dest_reg < num_regs; ++shorty_pos, ++dest_reg, ++arg_offset) {
+      DCHECK_LT(shorty_pos + 1, mh.GetShortyLength());
+      const size_t src_reg = (is_range) ? vregC + arg_offset : arg[arg_offset];
+      switch (shorty[shorty_pos + 1]) {
+        case 'L': {
+          Object* o = shadow_frame.GetVRegReference(src_reg);
+          if (do_assignability_check && o != NULL) {
+            Class* arg_type = mh.GetClassFromTypeIdx(params->GetTypeItem(shorty_pos).type_idx_);
+            if (arg_type == NULL) {
+              CHECK(self->IsExceptionPending());
+              return false;
+            }
+            if (!o->VerifierInstanceOf(arg_type)) {
+              // This should never happen.
+              self->ThrowNewExceptionF(self->GetCurrentLocationForThrow(),
+                                       "Ljava/lang/VirtualMachineError;",
+                                       "Invoking %s with bad arg %d, type '%s' not instance of '%s'",
+                                       mh.GetName(), shorty_pos,
+                                       ClassHelper(o->GetClass()).GetDescriptor(),
+                                       ClassHelper(arg_type).GetDescriptor());
+              return false;
+            }
           }
+          new_shadow_frame->SetVRegReference(dest_reg, o);
+          break;
         }
-        new_shadow_frame->SetVRegReference(cur_reg, o);
-        break;
+        case 'J': case 'D': {
+          uint64_t wide_value = (static_cast<uint64_t>(shadow_frame.GetVReg(src_reg + 1)) << 32) |
+                                static_cast<uint32_t>(shadow_frame.GetVReg(src_reg));
+          new_shadow_frame->SetVRegLong(dest_reg, wide_value);
+          ++dest_reg;
+          ++arg_offset;
+          break;
+        }
+        default:
+          new_shadow_frame->SetVReg(dest_reg, shadow_frame.GetVReg(src_reg));
+          break;
       }
-      case 'J': case 'D': {
-        uint64_t wide_value = (static_cast<uint64_t>(shadow_frame.GetVReg(arg_pos + 1)) << 32) |
-                              static_cast<uint32_t>(shadow_frame.GetVReg(arg_pos));
-        new_shadow_frame->SetVRegLong(cur_reg, wide_value);
-        ++cur_reg;
-        ++arg_offset;
-        break;
+    }
+  } else {
+    // Fast path: no extra checks.
+    if (is_range) {
+      const uint16_t first_src_reg = inst->VRegC_3rc();
+      for (size_t src_reg = first_src_reg, dest_reg = first_dest_reg; dest_reg < num_regs;
+          ++dest_reg, ++src_reg) {
+        AssignRegister(*new_shadow_frame, shadow_frame, dest_reg, src_reg);
+      }
+    } else {
+      DCHECK_LE(num_ins, 5U);
+      uint16_t regList = inst->Fetch16(2);
+      uint16_t count = num_ins;
+      if (count == 5) {
+        AssignRegister(*new_shadow_frame, shadow_frame, first_dest_reg + 4U, (inst_data >> 8) & 0x0f);
+        --count;
+       }
+      for (size_t arg_index = 0; arg_index < count; ++arg_index, regList >>= 4) {
+        AssignRegister(*new_shadow_frame, shadow_frame, first_dest_reg + arg_index, regList & 0x0f);
       }
-      default:
-        new_shadow_frame->SetVReg(cur_reg, shadow_frame.GetVReg(arg_pos));
-        break;
     }
   }
 
@@ -113,7 +149,7 @@ bool DoCall(ArtMethod* method, Object* receiver, Thread* self, ShadowFrame& shad
   if (LIKELY(Runtime::Current()->IsStarted())) {
     (method->GetEntryPointFromInterpreter())(self, mh, code_item, new_shadow_frame, result);
   } else {
-    UnstartedRuntimeInvoke(self, mh, code_item, new_shadow_frame, result, num_regs - num_ins);
+    UnstartedRuntimeInvoke(self, mh, code_item, new_shadow_frame, result, first_dest_reg);
   }
   return !self->IsExceptionPending();
 }