56a486c322
- this avoids using relative include paths which are forbidden by the style guide - makes the code more readable since it's clear which header is meant - allows for starting to use checkdeps BUG=none R=jkummerow@chromium.org, danno@chromium.org LOG=n Review URL: https://codereview.chromium.org/304153016 git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21625 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
55 lines
1.7 KiB
C++
55 lines
1.7 KiB
C++
// Copyright 2013 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "src/hydrogen-mark-unreachable.h"
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namespace v8 {
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namespace internal {
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void HMarkUnreachableBlocksPhase::MarkUnreachableBlocks() {
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// If there is unreachable code in the graph, propagate the unreachable marks
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// using a fixed-point iteration.
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bool changed = true;
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const ZoneList<HBasicBlock*>* blocks = graph()->blocks();
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while (changed) {
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changed = false;
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for (int i = 0; i < blocks->length(); i++) {
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HBasicBlock* block = blocks->at(i);
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if (!block->IsReachable()) continue;
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bool is_reachable = blocks->at(0) == block;
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for (HPredecessorIterator it(block); !it.Done(); it.Advance()) {
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HBasicBlock* predecessor = it.Current();
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// A block is reachable if one of its predecessors is reachable,
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// doesn't deoptimize and either is known to transfer control to the
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// block or has a control flow instruction for which the next block
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// cannot be determined.
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if (predecessor->IsReachable() && !predecessor->IsDeoptimizing()) {
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HBasicBlock* pred_succ;
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bool known_pred_succ =
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predecessor->end()->KnownSuccessorBlock(&pred_succ);
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if (!known_pred_succ || pred_succ == block) {
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is_reachable = true;
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break;
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}
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}
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if (block->is_osr_entry()) {
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is_reachable = true;
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}
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}
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if (!is_reachable) {
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block->MarkUnreachable();
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changed = true;
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}
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}
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}
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}
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void HMarkUnreachableBlocksPhase::Run() {
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MarkUnreachableBlocks();
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}
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} } // namespace v8::internal
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