Initial support for length guards on final fields.

runtime/vm/intermediate_language_arm.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM.
 #if defined(TARGET_ARCH_ARM)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/dart_entry.h"
@@ skipping 1499 matching lines @@
       UNREACHABLE();
   }
 }
 
 
 LocationSummary* GuardFieldInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
   LocationSummary* summary =
       new LocationSummary(kNumInputs, 0, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresRegister());
-  if ((value()->Type()->ToCid() == kDynamicCid) &&
-      (field().guarded_cid() != kSmiCid)) {
+  const bool field_has_length = field().needs_length_check();
+  const bool need_value_temp_reg =
+      (field_has_length || ((value()->Type()->ToCid() == kDynamicCid) &&
+                            (field().guarded_cid() != kSmiCid)));
+  if (need_value_temp_reg) {
     summary->AddTemp(Location::RequiresRegister());
   }
-  if (field().guarded_cid() == kIllegalCid) {
+  const bool need_field_temp_reg =
+      field_has_length || (field().guarded_cid() == kIllegalCid);
+  if (need_field_temp_reg) {
     summary->AddTemp(Location::RequiresRegister());
   }
   return summary;
 }
 
 
 void GuardFieldInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   const intptr_t field_cid = field().guarded_cid();
   const intptr_t nullability = field().is_nullable() ? kNullCid : kIllegalCid;
+  const intptr_t field_length = field().guarded_list_length();
+  const bool field_has_length = field().needs_length_check();
+  const bool needs_value_temp_reg =
+      (field_has_length || ((value()->Type()->ToCid() == kDynamicCid) &&
+                            (field().guarded_cid() != kSmiCid)));
+  const bool needs_field_temp_reg =
+      field_has_length || (field().guarded_cid() == kIllegalCid);
+  if (field_has_length) {
+    // Currently, we should only see final fields that remember length.
+    ASSERT(field().is_final());
+  }
 
   if (field_cid == kDynamicCid) {
     ASSERT(!compiler->is_optimizing());
     return;  // Nothing to emit.
   }
 
   const intptr_t value_cid = value()->Type()->ToCid();
 
   Register value_reg = locs()->in(0).reg();
 
-  Register value_cid_reg = ((value_cid == kDynamicCid) &&
-      (field_cid != kSmiCid)) ? locs()->temp(0).reg() : kNoRegister;
+  Register value_cid_reg = needs_value_temp_reg ?
+      locs()->temp(0).reg() : kNoRegister;
 
-  Register field_reg = (field_cid == kIllegalCid) ?
+  Register field_reg = needs_field_temp_reg ?
       locs()->temp(locs()->temp_count() - 1).reg() : kNoRegister;
 
   Label ok, fail_label;
 
   Label* deopt = compiler->is_optimizing() ?
       compiler->AddDeoptStub(deopt_id(), kDeoptGuardField) : NULL;
 
   Label* fail = (deopt != NULL) ? deopt : &fail_label;
 
   const bool ok_is_fall_through = (deopt != NULL);
 
   if (!compiler->is_optimizing() || (field_cid == kIllegalCid)) {
-    if (!compiler->is_optimizing()) {
+    if (!compiler->is_optimizing() && (field_reg == kNoRegister)) {
       // Currently we can't have different location summaries for optimized
       // and non-optimized code. So instead we manually pick up a register
       // that is known to be free because we know how non-optimizing compiler
       // allocates registers.
       field_reg = R2;
       ASSERT((field_reg != value_reg) && (field_reg != value_cid_reg));
     }
 
     __ LoadObject(field_reg, Field::ZoneHandle(field().raw()));
 
     FieldAddress field_cid_operand(field_reg, Field::guarded_cid_offset());
     FieldAddress field_nullability_operand(
         field_reg, Field::is_nullable_offset());
+    FieldAddress field_length_operand(
+        field_reg, Field::guarded_list_length_offset());
 
     if (value_cid_reg == kNoRegister) {
       ASSERT(!compiler->is_optimizing());
       value_cid_reg = R3;
       ASSERT((value_cid_reg != value_reg) && (field_reg != value_cid_reg));
     }
 
     if (value_cid == kDynamicCid) {
       LoadValueCid(compiler, value_cid_reg, value_reg);
+      Label skip_length_check;
       __ ldr(IP, field_cid_operand);
       __ cmp(value_cid_reg, ShifterOperand(IP));
-      __ b(&ok, EQ);
+      __ b(&skip_length_check, NE);
+      if (field_has_length) {
+        // Field guard may have remembered list length, check it.
+        if ((field_cid == kArrayCid) || (field_cid == kImmutableArrayCid)) {
+          __ Push(value_cid_reg);

[regis, 2013/08/20 21:24:04]

Instead of all the push/pop pairs below, can you allocate one more temp register
and use it?

[Cutch, 2013/08/20 22:48:51]

Done.

+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, Array::length_offset()));
+          __ CompareImmediate(value_cid_reg, field_length);
+          __ Pop(value_cid_reg);
+        } else if (RawObject::IsTypedDataClassId(field_cid)) {
+          __ Push(value_cid_reg);
+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, TypedData::length_offset()));
+          __ CompareImmediate(value_cid_reg, field_length);
+          __ Pop(value_cid_reg);
+        } else {
+          ASSERT(field_cid == kIllegalCid);
+          // Following branch cannot not occur, fall through.
+        }
+        __ b(fail, NE);
+      }
+      __ Bind(&skip_length_check);
       __ ldr(IP, field_nullability_operand);
       __ cmp(value_cid_reg, ShifterOperand(IP));
     } else if (value_cid == kNullCid) {
       __ ldr(value_cid_reg, field_nullability_operand);
       __ CompareImmediate(value_cid_reg, value_cid);
     } else {
+      Label skip_length_check;
       __ ldr(value_cid_reg, field_cid_operand);
       __ CompareImmediate(value_cid_reg, value_cid);
+      __ b(&skip_length_check, NE);
+      if (field_has_length) {
+        ASSERT(value_cid_reg != kNoRegister);
+        if ((field_cid == kArrayCid) || (field_cid == kImmutableArrayCid)) {
+          __ Push(value_cid_reg);
+          __ ldr(value_cid_reg,
+                  FieldAddress(value_reg, Array::length_offset()));
+          __ CompareImmediate(value_cid_reg, field_length);
+          __ Pop(value_cid_reg);
+        } else if (RawObject::IsTypedDataClassId(field_cid)) {
+          __ Push(value_cid_reg);
+          __ ldr(value_cid_reg,
+                  FieldAddress(value_reg, TypedData::length_offset()));
+          __ CompareImmediate(value_cid_reg, field_length);
+          __ Pop(value_cid_reg);
+        } else {
+          ASSERT(field_cid == kIllegalCid);
+          // Following jump cannot not occur, fall through.
+        }
+      }
+      // Not identical, possibly null.
+      __ Bind(&skip_length_check);
     }
     __ b(&ok, EQ);
 
     __ ldr(IP, field_cid_operand);
     __ CompareImmediate(IP, kIllegalCid);
     __ b(fail, NE);
 
     if (value_cid == kDynamicCid) {
       __ str(value_cid_reg, field_cid_operand);
       __ str(value_cid_reg, field_nullability_operand);
+      if (field_has_length) {
+        Label check_array, local_exit, local_fail;
+        __ CompareImmediate(value_cid_reg, kNullCid);
+        __ b(&local_fail, EQ);
+        // Check for typed data array.
+        __ CompareImmediate(value_cid_reg, kTypedDataFloat32x4ArrayCid);
+        __ b(&local_fail, GT);
+        __ CompareImmediate(value_cid_reg, kTypedDataInt8ArrayCid);
+        __ b(&check_array, LT);  // Could still be a regular array.
+        // Destroy value_cid_reg (safe because we are finished with it).
+        __ ldr(value_cid_reg,
+               FieldAddress(value_reg, TypedData::length_offset()));
+        __ str(value_cid_reg, field_length_operand);
+        __ b(&local_exit);  // Updated field length typed data array.
+        // Check for regular array.
+        __ Bind(&check_array);
+        __ CompareImmediate(value_cid_reg, kImmutableArrayCid);
+        __ b(&local_fail, GT);
+        __ CompareImmediate(value_cid_reg, kArrayCid);
+        __ b(&local_fail, LT);
+        // Destroy value_cid_reg (safe because we are finished with it).
+        __ ldr(value_cid_reg,
+               FieldAddress(value_reg, Array::length_offset()));
+        __ str(value_cid_reg, field_length_operand);
+        __ b(&local_exit);  // Updated field length from regular array.
+
+        __ Bind(&local_fail);
+        __ LoadImmediate(IP, Field::kNoFixedLength);
+        __ str(IP, field_length_operand);
+
+        __ Bind(&local_exit);
+      }
     } else {
       __ LoadImmediate(IP, value_cid);
       __ str(IP, field_cid_operand);
       __ str(IP, field_nullability_operand);
+      if ((value_cid == kArrayCid) || (value_cid == kImmutableArrayCid)) {
+        // Destroy value_cid_reg (safe because we are finished with it).
+        __ ldr(value_cid_reg,
+               FieldAddress(value_reg, Array::length_offset()));
+        __ str(value_cid_reg, field_length_operand);
+      } else if (RawObject::IsTypedDataClassId(value_cid)) {
+        // Destroy value_cid_reg (safe because we are finished with it).
+        __ ldr(value_cid_reg,
+                FieldAddress(value_reg, TypedData::length_offset()));
+        __ str(value_cid_reg, field_length_operand);
+      } else {
+        __ LoadImmediate(IP, Field::kNoFixedLength);
+        __ str(IP, field_length_operand);
+      }
     }
 
     if (!ok_is_fall_through) {
       __ b(&ok);
     }
   } else {
+    if (field_reg != kNoRegister) {
+      __ LoadObject(field_reg, Field::ZoneHandle(field().raw()));
+    }
     if (value_cid == kDynamicCid) {
       // Field's guarded class id is fixed by value's class id is not known.
       __ tst(value_reg, ShifterOperand(kSmiTagMask));
 
       if (field_cid != kSmiCid) {
         __ b(fail, EQ);
         __ LoadClassId(value_cid_reg, value_reg);
         __ CompareImmediate(value_cid_reg, field_cid);
       }
 
+      if (field_has_length) {
+        __ b(fail, NE);
+        // Classes are same, perform guarded list length check.
+        ASSERT(field_reg != kNoRegister);
+        ASSERT(value_cid_reg != kNoRegister);
+        FieldAddress field_length_operand(
+            field_reg, Field::guarded_list_length_offset());
+        if ((field_cid == kArrayCid) || (field_cid == kImmutableArrayCid)) {
+          // Destroy value_cid_reg (safe because we are finished with it).
+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, Array::length_offset()));
+        } else if (RawObject::IsTypedDataClassId(field_cid)) {
+          // Destroy value_cid_reg (safe because we are finished with it).
+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, TypedData::length_offset()));
+        }
+        __ ldr(IP, field_length_operand);
+        __ cmp(value_cid_reg, ShifterOperand(IP));
+      }
+
       if (field().is_nullable() && (field_cid != kNullCid)) {
         __ b(&ok, EQ);
         __ CompareImmediate(value_reg,
                             reinterpret_cast<intptr_t>(Object::null()));
       }
 
       if (ok_is_fall_through) {
         __ b(fail, NE);
       } else {
         __ b(&ok, EQ);
       }
     } else {
       // Both value's and field's class id is known.
       if ((value_cid != field_cid) && (value_cid != nullability)) {
         if (ok_is_fall_through) {
           __ b(fail);
         }
+      } else if (field_has_length && (value_cid == field_cid)) {
+        ASSERT(value_cid_reg != kNoRegister);
+        if ((field_cid == kArrayCid) || (field_cid == kImmutableArrayCid)) {
+          // Destroy value_cid_reg (safe because we are finished with it).
+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, Array::length_offset()));
+        } else if (RawObject::IsTypedDataClassId(field_cid)) {
+          // Destroy value_cid_reg (safe because we are finished with it).
+          __ ldr(value_cid_reg,
+                 FieldAddress(value_reg, TypedData::length_offset()));
+        }
+        __ LoadImmediate(IP, field_length);
+        __ cmp(value_cid_reg, ShifterOperand(IP));
+        if (ok_is_fall_through) {
+          __ b(fail, NE);
+        }
       } else {
         // Nothing to emit.
         ASSERT(!compiler->is_optimizing());
         return;
       }
     }
   }
 
   if (deopt == NULL) {
     ASSERT(!compiler->is_optimizing());
@@ skipping 2807 matching lines @@
   compiler->GenerateCall(token_pos(),
                          &label,
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM