Ryan Macnak
91ed534139
- Don't use PC-relative calls when calling between loading units. - Sort the contents of the code cluster by loading unit, then by text offset. - Handle binding PC-relatives calls and inserting trampolines per loading unit. - Create one code order table per loading unit to implement PC -> Code lookup. - Read code order tables directly, instead of copying into malloc'd memory. --use_table_dispatch still not yet supported. This slightly shrinks non-split binaries (~2% clustered part, 0.4% total snapshot) due to the new delta encoding when Code references Instructions. Bug: https://github.com/dart-lang/sdk/issues/41974 Change-Id: I51052ebc7b4968b554897d1710135a6c41821302 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/157820 Commit-Queue: Ryan Macnak <rmacnak@google.com> Reviewed-by: Alexander Markov <alexmarkov@google.com> Reviewed-by: Tess Strickland <sstrickl@google.com>
71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#include "vm/reverse_pc_lookup_cache.h"
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#include "vm/isolate.h"
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#include "vm/object.h"
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#include "vm/object_store.h"
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namespace dart {
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CodePtr ReversePc::Lookup(IsolateGroup* group,
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uword pc,
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bool is_return_address) {
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#if defined(DART_PRECOMPILED_RUNTIME)
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// This can run in the middle of GC and must not allocate handles.
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NoSafepointScope no_safepoint;
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if (is_return_address) {
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pc--;
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}
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// This expected number of tables is low, so we go through them linearly. If
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// this changes, would could sort the table list during deserialization and
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// binary search for the table.
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GrowableObjectArrayPtr tables = group->object_store()->code_order_tables();
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intptr_t tables_length = Smi::Value(tables->ptr()->length_);
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for (intptr_t i = 0; i < tables_length; i++) {
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ArrayPtr table =
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static_cast<ArrayPtr>(tables->ptr()->data_->ptr()->data()[i]);
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intptr_t lo = 0;
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intptr_t hi = Smi::Value(table->ptr()->length_) - 1;
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// Fast check if pc belongs to this table.
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if (lo > hi) {
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continue;
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}
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CodePtr first = static_cast<CodePtr>(table->ptr()->data()[lo]);
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if (pc < Code::PayloadStartOf(first)) {
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continue;
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}
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CodePtr last = static_cast<CodePtr>(table->ptr()->data()[hi]);
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if (pc >= (Code::PayloadStartOf(last) + Code::PayloadSizeOf(last))) {
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continue;
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}
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// Binary search within the table for the matching Code.
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while (lo <= hi) {
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intptr_t mid = (hi - lo + 1) / 2 + lo;
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ASSERT(mid >= lo);
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ASSERT(mid <= hi);
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CodePtr code = static_cast<CodePtr>(table->ptr()->data()[mid]);
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uword code_start = Code::PayloadStartOf(code);
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uword code_end = code_start + Code::PayloadSizeOf(code);
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if (pc < code_start) {
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hi = mid - 1;
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} else if (pc >= code_end) {
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lo = mid + 1;
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} else {
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return code;
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}
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}
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}
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#endif // defined(DART_PRECOMPILED_RUNTIME)
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return Code::null();
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}
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} // namespace dart
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