Embedded constant pools.

src/frames.cc

 // Copyright 2012 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.
 
 #include "src/frames.h"
 
 #include <sstream>
 
 #include "src/v8.h"
 
@@ skipping 303 matching lines @@
       SingletonFor(frame->GetCallerState(&state)) != NULL;
 }
 
 
 bool SafeStackFrameIterator::IsValidExitFrame(Address fp) const {
   if (!IsValidStackAddress(fp)) return false;
   Address sp = ExitFrame::ComputeStackPointer(fp);
   if (!IsValidStackAddress(sp)) return false;
   StackFrame::State state;
   ExitFrame::FillState(fp, sp, &state);
-  if (!IsValidStackAddress(reinterpret_cast<Address>(state.pc_address))) {
-    return false;
-  }

[rmcilroy, 2015/05/20 14:32:11]

Why are you removing this?

[MTBrandyberry, 2015/05/20 22:28:22]

By definition, the an exit frame's pc_address is above sp (see
ExitFrame::FillState).  Thus, this check always fails.

This appears to be harmless for frames without the constant pool slot, but
causes real issues otherwise.  IIRC, it leads to clobbering constant pool
register upon return in some cases.

   return *state.pc_address != NULL;
 }
 
 
 void SafeStackFrameIterator::Advance() {
   while (true) {
     AdvanceOneFrame();
     if (done()) return;
     if (frame_->is_java_script()) return;
     if (frame_->is_exit() && external_callback_scope_) {
@@ skipping 41 matching lines @@
   *stack_slots = code->stack_slots();
   return code;
 }
 
 
 #ifdef DEBUG
 static bool GcSafeCodeContains(HeapObject* object, Address addr);
 #endif
 
 
-void StackFrame::IteratePc(ObjectVisitor* v,
-                           Address* pc_address,
-                           Code* holder) {
+void StackFrame::IteratePc(ObjectVisitor* v, Address* pc_address,
+                           Address* constant_pool_address, Code* holder) {
   Address pc = *pc_address;
   DCHECK(GcSafeCodeContains(holder, pc));
   unsigned pc_offset = static_cast<unsigned>(pc - holder->instruction_start());
   Object* code = holder;
   v->VisitPointer(&code);
   if (code != holder) {
     holder = reinterpret_cast<Code*>(code);
     pc = holder->instruction_start() + pc_offset;
     *pc_address = pc;
+    if (FLAG_enable_embedded_constant_pool && constant_pool_address) {
+      *constant_pool_address = holder->constant_pool();
+    }
   }
 }
 
 
 void StackFrame::SetReturnAddressLocationResolver(
     ReturnAddressLocationResolver resolver) {
   DCHECK(return_address_location_resolver_ == NULL);
   return_address_location_resolver_ = resolver;
 }
 
@@ skipping 89 matching lines @@
   return reinterpret_cast<Code*>(code_slot());
 }
 
 
 void ExitFrame::ComputeCallerState(State* state) const {
   // Set up the caller state.
   state->sp = caller_sp();
   state->fp = Memory::Address_at(fp() + ExitFrameConstants::kCallerFPOffset);
   state->pc_address = ResolveReturnAddressLocation(
       reinterpret_cast<Address*>(fp() + ExitFrameConstants::kCallerPCOffset));
-  if (FLAG_enable_ool_constant_pool) {
+  if (FLAG_enable_embedded_constant_pool) {
     state->constant_pool_address = reinterpret_cast<Address*>(
         fp() + ExitFrameConstants::kConstantPoolOffset);
   }
 }
 
 
 void ExitFrame::SetCallerFp(Address caller_fp) {
   Memory::Address_at(fp() + ExitFrameConstants::kCallerFPOffset) = caller_fp;
 }
 
 
 void ExitFrame::Iterate(ObjectVisitor* v) const {
   // The arguments are traversed as part of the expression stack of
   // the calling frame.
-  IteratePc(v, pc_address(), LookupCode());
+  IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
   v->VisitPointer(&code_slot());
-  if (FLAG_enable_ool_constant_pool) {
-    v->VisitPointer(&constant_pool_slot());
-  }
 }
 
 
 Address ExitFrame::GetCallerStackPointer() const {
   return fp() + ExitFrameConstants::kCallerSPDisplacement;
 }
 
 
 StackFrame::Type ExitFrame::GetStateForFramePointer(Address fp, State* state) {
   if (fp == 0) return NONE;
   Address sp = ComputeStackPointer(fp);
   FillState(fp, sp, state);
   DCHECK(*state->pc_address != NULL);
   return EXIT;
 }
 
 
 Address ExitFrame::ComputeStackPointer(Address fp) {
   return Memory::Address_at(fp + ExitFrameConstants::kSPOffset);
 }
 
 
 void ExitFrame::FillState(Address fp, Address sp, State* state) {
   state->sp = sp;
   state->fp = fp;
   state->pc_address = ResolveReturnAddressLocation(
       reinterpret_cast<Address*>(sp - 1 * kPCOnStackSize));
-  state->constant_pool_address =
-      reinterpret_cast<Address*>(fp + ExitFrameConstants::kConstantPoolOffset);
+  // The constant pool recorded in the exit frame is not associated
+  // with the pc in this state (the return address into a C entry
+  // stub).  ComputeCallerState will retrieve the constant pool
+  // together with the associated caller pc.
+  state->constant_pool_address = NULL;
 }
 
 
 Address StandardFrame::GetExpressionAddress(int n) const {
   const int offset = StandardFrameConstants::kExpressionsOffset;
   return fp() + offset - n * kPointerSize;
 }
 
 
 Object* StandardFrame::GetExpression(Address fp, int index) {
@@ skipping 88 matching lines @@
   // Visit pointer spill slots and locals.
   for (unsigned index = 0; index < stack_slots; index++) {
     int byte_index = index >> kBitsPerByteLog2;
     int bit_index = index & (kBitsPerByte - 1);
     if ((safepoint_bits[byte_index] & (1U << bit_index)) != 0) {
       v->VisitPointer(parameters_limit + index);
     }
   }
 
   // Visit the return address in the callee and incoming arguments.
-  IteratePc(v, pc_address(), code);
+  IteratePc(v, pc_address(), constant_pool_address(), code);
 
   // Visit the context in stub frame and JavaScript frame.
   // Visit the function in JavaScript frame.
   Object** fixed_base = &Memory::Object_at(
       fp() + StandardFrameConstants::kMarkerOffset);
   Object** fixed_limit = &Memory::Object_at(fp());
   v->VisitPointers(fixed_base, fixed_limit);
 }
 
 
@@ skipping 601 matching lines @@
       accumulator->Add("  // not passed to callee");
     }
     accumulator->Add("\n");
   }
 
   accumulator->Add("}\n\n");
 }
 
 
 void EntryFrame::Iterate(ObjectVisitor* v) const {
-  IteratePc(v, pc_address(), LookupCode());
+  IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
 }
 
 
 void StandardFrame::IterateExpressions(ObjectVisitor* v) const {
   const int offset = StandardFrameConstants::kLastObjectOffset;
   Object** base = &Memory::Object_at(sp());
   Object** limit = &Memory::Object_at(fp() + offset) + 1;
   v->VisitPointers(base, limit);
 }
 
 
 void JavaScriptFrame::Iterate(ObjectVisitor* v) const {
   IterateExpressions(v);
-  IteratePc(v, pc_address(), LookupCode());
+  IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
 }
 
 
 void InternalFrame::Iterate(ObjectVisitor* v) const {
   // Internal frames only have object pointers on the expression stack
   // as they never have any arguments.
   IterateExpressions(v);
-  IteratePc(v, pc_address(), LookupCode());
+  IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
 }
 
 
 void StubFailureTrampolineFrame::Iterate(ObjectVisitor* v) const {
   Object** base = &Memory::Object_at(sp());
   Object** limit = &Memory::Object_at(fp() +
                                       kFirstRegisterParameterFrameOffset);
   v->VisitPointers(base, limit);
   base = &Memory::Object_at(fp() + StandardFrameConstants::kMarkerOffset);
   const int offset = StandardFrameConstants::kLastObjectOffset;
   limit = &Memory::Object_at(fp() + offset) + 1;
   v->VisitPointers(base, limit);
-  IteratePc(v, pc_address(), LookupCode());
+  IteratePc(v, pc_address(), constant_pool_address(), LookupCode());
 }
 
 
 Address StubFailureTrampolineFrame::GetCallerStackPointer() const {
   return fp() + StandardFrameConstants::kCallerSPOffset;
 }
 
 
 Code* StubFailureTrampolineFrame::unchecked_code() const {
   Code* trampoline;
@@ skipping 180 matching lines @@
   ZoneList<StackFrame*> list(10, zone);
   for (StackFrameIterator it(isolate); !it.done(); it.Advance()) {
     StackFrame* frame = AllocateFrameCopy(it.frame(), zone);
     list.Add(frame, zone);
   }
   return list.ToVector();
 }
 
 
 } }  // namespace v8::internal