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// Copyright (c) 2021, 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/pending_deopts.h"
#include "vm/log.h"
#include "vm/stack_frame.h"
#include "vm/stub_code.h"
namespace dart {
DECLARE_FLAG(bool, trace_deoptimization);
PendingDeopts::PendingDeopts()
: pending_deopts_(new MallocGrowableArray<PendingLazyDeopt>()) {}
PendingDeopts::~PendingDeopts() {
delete pending_deopts_;
pending_deopts_ = nullptr;
}
void PendingDeopts::AddPendingDeopt(uword fp, uword pc) {
// GrowableArray::Add is not atomic and may be interrupted by a profiler
// stack walk.
MallocGrowableArray<PendingLazyDeopt>* old_pending_deopts = pending_deopts_;
MallocGrowableArray<PendingLazyDeopt>* new_pending_deopts =
new MallocGrowableArray<PendingLazyDeopt>(old_pending_deopts->length() +
1);
for (intptr_t i = 0; i < old_pending_deopts->length(); i++) {
ASSERT((*old_pending_deopts)[i].fp() != fp);
new_pending_deopts->Add((*old_pending_deopts)[i]);
}
PendingLazyDeopt deopt(fp, pc);
new_pending_deopts->Add(deopt);
pending_deopts_ = new_pending_deopts;
delete old_pending_deopts;
}
uword PendingDeopts::FindPendingDeopt(uword fp) {
for (intptr_t i = 0; i < pending_deopts_->length(); i++) {
if ((*pending_deopts_)[i].fp() == fp) {
return (*pending_deopts_)[i].pc();
}
}
FATAL("Missing pending deopt entry");
return 0;
}
void PendingDeopts::ClearPendingDeoptsBelow(uword fp, ClearReason reason) {
for (intptr_t i = pending_deopts_->length() - 1; i >= 0; i--) {
if ((*pending_deopts_)[i].fp() < fp) {
if (FLAG_trace_deoptimization) {
switch (reason) {
case kClearDueToThrow:
THR_Print(
"Lazy deopt skipped due to throw for "
"fp=%" Pp ", pc=%" Pp "\n",
(*pending_deopts_)[i].fp(), (*pending_deopts_)[i].pc());
break;
case kClearDueToDeopt:
THR_Print("Lazy deopt fp=%" Pp " pc=%" Pp "\n",
(*pending_deopts_)[i].fp(), (*pending_deopts_)[i].pc());
break;
}
}
pending_deopts_->RemoveAt(i);
}
}
}
void PendingDeopts::ClearPendingDeoptsAtOrBelow(uword fp, ClearReason reason) {
ClearPendingDeoptsBelow(fp + kWordSize, reason);
}
uword PendingDeopts::RemapExceptionPCForDeopt(uword program_counter,
uword frame_pointer,
bool* clear_deopt) {
*clear_deopt = false;
// Do not attempt to deopt at async exception handler as it doesn't
// belong to the function code. Async handler never continues execution
// in the same frame - it either rethrows exception to the caller or
// tail calls Dart handler, leaving the function frame before the call.
if (program_counter == StubCode::AsyncExceptionHandler().EntryPoint()) {
*clear_deopt = true;
return program_counter;
}
// Check if the target frame is scheduled for lazy deopt.
for (intptr_t i = 0; i < pending_deopts_->length(); i++) {
if ((*pending_deopts_)[i].fp() == frame_pointer) {
// Deopt should now resume in the catch handler instead of after the
// call.
(*pending_deopts_)[i].set_pc(program_counter);
// Jump to the deopt stub instead of the catch handler.
program_counter = StubCode::DeoptimizeLazyFromThrow().EntryPoint();
if (FLAG_trace_deoptimization) {
THR_Print("Throwing to frame scheduled for lazy deopt fp=%" Pp "\n",
frame_pointer);
#if defined(DEBUG)
// Ensure the frame references optimized code.
ObjectPtr pc_marker = *(reinterpret_cast<ObjectPtr*>(
frame_pointer + runtime_frame_layout.code_from_fp * kWordSize));
Code& code = Code::Handle(Code::RawCast(pc_marker));
ASSERT(code.is_optimized() && !code.is_force_optimized());
#endif
}
break;
}
}
return program_counter;
}
} // namespace dart