summaryrefslogtreecommitdiff
path: root/deps/v8/src/crankshaft/hydrogen-store-elimination.cc
diff options
context:
space:
mode:
Diffstat (limited to 'deps/v8/src/crankshaft/hydrogen-store-elimination.cc')
-rw-r--r--deps/v8/src/crankshaft/hydrogen-store-elimination.cc122
1 files changed, 0 insertions, 122 deletions
diff --git a/deps/v8/src/crankshaft/hydrogen-store-elimination.cc b/deps/v8/src/crankshaft/hydrogen-store-elimination.cc
deleted file mode 100644
index b081c21984..0000000000
--- a/deps/v8/src/crankshaft/hydrogen-store-elimination.cc
+++ /dev/null
@@ -1,122 +0,0 @@
-// Copyright 2013 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/crankshaft/hydrogen-store-elimination.h"
-
-#include "src/crankshaft/hydrogen-instructions.h"
-#include "src/objects-inl.h"
-
-namespace v8 {
-namespace internal {
-
-#define TRACE(x) if (FLAG_trace_store_elimination) PrintF x
-
-// Performs a block-by-block local analysis for removable stores.
-void HStoreEliminationPhase::Run() {
- GVNFlagSet flags; // Use GVN flags as an approximation for some instructions.
- flags.RemoveAll();
-
- flags.Add(kArrayElements);
- flags.Add(kArrayLengths);
- flags.Add(kStringLengths);
- flags.Add(kBackingStoreFields);
- flags.Add(kDoubleArrayElements);
- flags.Add(kDoubleFields);
- flags.Add(kElementsPointer);
- flags.Add(kInobjectFields);
- flags.Add(kExternalMemory);
- flags.Add(kStringChars);
- flags.Add(kTypedArrayElements);
-
- for (int i = 0; i < graph()->blocks()->length(); i++) {
- unobserved_.Rewind(0);
- HBasicBlock* block = graph()->blocks()->at(i);
- if (!block->IsReachable()) continue;
- for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
- HInstruction* instr = it.Current();
- if (instr->CheckFlag(HValue::kIsDead)) continue;
-
- switch (instr->opcode()) {
- case HValue::kStoreNamedField:
- // Remove any unobserved stores overwritten by this store.
- ProcessStore(HStoreNamedField::cast(instr));
- break;
- case HValue::kLoadNamedField:
- // Observe any unobserved stores on this object + field.
- ProcessLoad(HLoadNamedField::cast(instr));
- break;
- default:
- ProcessInstr(instr, flags);
- break;
- }
- }
- }
-}
-
-
-void HStoreEliminationPhase::ProcessStore(HStoreNamedField* store) {
- HValue* object = store->object()->ActualValue();
- int i = 0;
- while (i < unobserved_.length()) {
- HStoreNamedField* prev = unobserved_.at(i);
- if (aliasing_->MustAlias(object, prev->object()->ActualValue()) &&
- prev->CanBeReplacedWith(store)) {
- // This store is guaranteed to overwrite the previous store.
- prev->DeleteAndReplaceWith(NULL);
- TRACE(("++ Unobserved store S%d overwritten by S%d\n",
- prev->id(), store->id()));
- unobserved_.Remove(i);
- } else {
- i++;
- }
- }
- // Only non-transitioning stores are removable.
- if (!store->has_transition()) {
- TRACE(("-- Might remove store S%d\n", store->id()));
- unobserved_.Add(store, zone());
- }
-}
-
-
-void HStoreEliminationPhase::ProcessLoad(HLoadNamedField* load) {
- HValue* object = load->object()->ActualValue();
- int i = 0;
- while (i < unobserved_.length()) {
- HStoreNamedField* prev = unobserved_.at(i);
- if (aliasing_->MayAlias(object, prev->object()->ActualValue()) &&
- load->access().Equals(prev->access())) {
- TRACE(("-- Observed store S%d by load L%d\n", prev->id(), load->id()));
- unobserved_.Remove(i);
- } else {
- i++;
- }
- }
-}
-
-
-void HStoreEliminationPhase::ProcessInstr(HInstruction* instr,
- GVNFlagSet flags) {
- if (unobserved_.length() == 0) return; // Nothing to do.
- if (instr->CanDeoptimize()) {
- TRACE(("-- Observed stores at I%d (%s might deoptimize)\n",
- instr->id(), instr->Mnemonic()));
- unobserved_.Rewind(0);
- return;
- }
- if (instr->CheckChangesFlag(kNewSpacePromotion)) {
- TRACE(("-- Observed stores at I%d (%s might GC)\n",
- instr->id(), instr->Mnemonic()));
- unobserved_.Rewind(0);
- return;
- }
- if (instr->DependsOnFlags().ContainsAnyOf(flags)) {
- TRACE(("-- Observed stores at I%d (GVN flags of %s)\n",
- instr->id(), instr->Mnemonic()));
- unobserved_.Rewind(0);
- return;
- }
-}
-
-} // namespace internal
-} // namespace v8