PPC: [for-in] Ensure that we learn from deopts within for-in loop bodies.

src/full-codegen/ppc/full-codegen-ppc.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_PPC
 
 #include "src/ast/scopes.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 1058 matching lines @@
   __ Push(r5, r4, r3);
   __ b(&loop);
 
   __ bind(&no_descriptors);
   __ Drop(1);
   __ b(&exit);
 
   // We got a fixed array in register r3. Iterate through that.
   __ bind(&fixed_array);
 
+  int const vector_index = SmiFromSlot(slot)->value();
   __ EmitLoadTypeFeedbackVector(r4);
   __ mov(r5, Operand(TypeFeedbackVector::MegamorphicSentinel(isolate())));
-  int vector_index = SmiFromSlot(slot)->value();
   __ StoreP(
       r5, FieldMemOperand(r4, FixedArray::OffsetOfElementAt(vector_index)), r0);
   __ LoadSmiLiteral(r4, Smi::FromInt(1));  // Smi(1) indicates slow check
   __ Push(r4, r3);  // Smi and array
   __ LoadP(r4, FieldMemOperand(r3, FixedArray::kLengthOffset));
   __ Push(r4);  // Fixed array length (as smi).
   PrepareForBailoutForId(stmt->PrepareId(), NO_REGISTERS);
   __ LoadSmiLiteral(r3, Smi::FromInt(0));
   __ Push(r3);  // Initial index.
 
@@ skipping 18 matching lines @@
   __ LoadP(r5, MemOperand(sp, 3 * kPointerSize));
 
   // Check if the expected map still matches that of the enumerable.
   // If not, we may have to filter the key.
   Label update_each;
   __ LoadP(r4, MemOperand(sp, 4 * kPointerSize));
   __ LoadP(r7, FieldMemOperand(r4, HeapObject::kMapOffset));
   __ cmp(r7, r5);
   __ beq(&update_each);
 
+  // We might get here from TurboFan or Crankshaft when something in the
+  // for-in loop body deopts and only now notice in fullcodegen, that we
+  // can now longer use the enum cache, i.e. left fast mode. So better record
+  // this information here, in case we later OSR back into this loop or
+  // reoptimize the whole function w/o rerunning the loop with the slow
+  // mode object in fullcodegen (which would result in a deopt loop).
+  __ EmitLoadTypeFeedbackVector(r3);
+  __ mov(r5, Operand(TypeFeedbackVector::MegamorphicSentinel(isolate())));
+  __ StoreP(
+      r5, FieldMemOperand(r3, FixedArray::OffsetOfElementAt(vector_index)), r0);
+
   // Convert the entry to a string or (smi) 0 if it isn't a property
   // any more. If the property has been removed while iterating, we
   // just skip it.
   __ Push(r4, r6);  // Enumerable and current entry.
   __ CallRuntime(Runtime::kForInFilter);
   PrepareForBailoutForId(stmt->FilterId(), TOS_REG);
   __ mr(r6, r3);
   __ LoadRoot(r0, Heap::kUndefinedValueRootIndex);
   __ cmp(r3, r0);
   __ beq(loop_statement.continue_label());
@@ skipping 3663 matching lines @@
     return ON_STACK_REPLACEMENT;
   }
 
   DCHECK(interrupt_address ==
          isolate->builtins()->OsrAfterStackCheck()->entry());
   return OSR_AFTER_STACK_CHECK;
 }
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_TARGET_ARCH_PPC