Index: src/hydrogen-uint32-analysis.cc |
diff --git a/src/hydrogen-uint32-analysis.cc b/src/hydrogen-uint32-analysis.cc |
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+// Copyright 2013 the V8 project authors. All rights reserved. |
+// Redistribution and use in source and binary forms, with or without |
+// modification, are permitted provided that the following conditions are |
+// met: |
+// |
+// * Redistributions of source code must retain the above copyright |
+// notice, this list of conditions and the following disclaimer. |
+// * Redistributions in binary form must reproduce the above |
+// copyright notice, this list of conditions and the following |
+// disclaimer in the documentation and/or other materials provided |
+// with the distribution. |
+// * Neither the name of Google Inc. nor the names of its |
+// contributors may be used to endorse or promote products derived |
+// from this software without specific prior written permission. |
+// |
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
+ |
+#include "hydrogen-uint32-analysis.h" |
+ |
+namespace v8 { |
+namespace internal { |
+ |
+ |
+bool HUint32AnalysisPhase::IsSafeUint32Use(HValue* val, HValue* use) { |
+ // Operations that operate on bits are safe. |
+ if (use->IsBitwise() || |
+ use->IsShl() || |
+ use->IsSar() || |
+ use->IsShr() || |
+ use->IsBitNot()) { |
+ return true; |
+ } else if (use->IsChange() || use->IsSimulate()) { |
+ // Conversions and deoptimization have special support for unt32. |
+ return true; |
+ } else if (use->IsStoreKeyed()) { |
+ HStoreKeyed* store = HStoreKeyed::cast(use); |
+ if (store->is_external()) { |
+ // Storing a value into an external integer array is a bit level |
+ // operation. |
+ if (store->value() == val) { |
+ // Clamping or a conversion to double should have beed inserted. |
+ ASSERT(store->elements_kind() != EXTERNAL_PIXEL_ELEMENTS); |
+ ASSERT(store->elements_kind() != EXTERNAL_FLOAT_ELEMENTS); |
+ ASSERT(store->elements_kind() != EXTERNAL_DOUBLE_ELEMENTS); |
+ return true; |
+ } |
+ } |
+ } |
+ |
+ return false; |
+} |
+ |
+ |
+// Iterate over all uses and verify that they are uint32 safe: either don't |
+// distinguish between int32 and uint32 due to their bitwise nature or |
+// have special support for uint32 values. |
+// Encountered phis are optimistically treated as safe uint32 uses, |
+// marked with kUint32 flag and collected in the phis_ list. A separate |
+// pass will be performed later by UnmarkUnsafePhis to clear kUint32 from |
+// phis that are not actually uint32-safe (it requires fix point iteration). |
+bool HUint32AnalysisPhase::Uint32UsesAreSafe(HValue* uint32val) { |
+ bool collect_phi_uses = false; |
+ for (HUseIterator it(uint32val->uses()); !it.Done(); it.Advance()) { |
+ HValue* use = it.value(); |
+ |
+ if (use->IsPhi()) { |
+ if (!use->CheckFlag(HInstruction::kUint32)) { |
+ // There is a phi use of this value from a phi that is not yet |
+ // collected in phis_ array. Separate pass is required. |
+ collect_phi_uses = true; |
+ } |
+ |
+ // Optimistically treat phis as uint32 safe. |
+ continue; |
+ } |
+ |
+ if (!IsSafeUint32Use(uint32val, use)) { |
+ return false; |
+ } |
+ } |
+ |
+ if (collect_phi_uses) { |
+ for (HUseIterator it(uint32val->uses()); !it.Done(); it.Advance()) { |
+ HValue* use = it.value(); |
+ |
+ // There is a phi use of this value from a phi that is not yet |
+ // collected in phis_ array. Separate pass is required. |
+ if (use->IsPhi() && !use->CheckFlag(HInstruction::kUint32)) { |
+ use->SetFlag(HInstruction::kUint32); |
+ phis_.Add(HPhi::cast(use), zone()); |
+ } |
+ } |
+ } |
+ |
+ return true; |
+} |
+ |
+ |
+// Check if all operands to the given phi are marked with kUint32 flag. |
+bool HUint32AnalysisPhase::CheckPhiOperands(HPhi* phi) { |
+ if (!phi->CheckFlag(HInstruction::kUint32)) { |
+ // This phi is not uint32 safe. No need to check operands. |
+ return false; |
+ } |
+ |
+ for (int j = 0; j < phi->OperandCount(); j++) { |
+ HValue* operand = phi->OperandAt(j); |
+ if (!operand->CheckFlag(HInstruction::kUint32)) { |
+ // Lazily mark constants that fit into uint32 range with kUint32 flag. |
+ if (operand->IsInteger32Constant() && |
+ operand->GetInteger32Constant() >= 0) { |
+ operand->SetFlag(HInstruction::kUint32); |
+ continue; |
+ } |
+ |
+ // This phi is not safe, some operands are not uint32 values. |
+ return false; |
+ } |
+ } |
+ |
+ return true; |
+} |
+ |
+ |
+// Remove kUint32 flag from the phi itself and its operands. If any operand |
+// was a phi marked with kUint32 place it into a worklist for |
+// transitive clearing of kUint32 flag. |
+void HUint32AnalysisPhase::UnmarkPhi(HPhi* phi, ZoneList<HPhi*>* worklist) { |
+ phi->ClearFlag(HInstruction::kUint32); |
+ for (int j = 0; j < phi->OperandCount(); j++) { |
+ HValue* operand = phi->OperandAt(j); |
+ if (operand->CheckFlag(HInstruction::kUint32)) { |
+ operand->ClearFlag(HInstruction::kUint32); |
+ if (operand->IsPhi()) { |
+ worklist->Add(HPhi::cast(operand), zone()); |
+ } |
+ } |
+ } |
+} |
+ |
+ |
+void HUint32AnalysisPhase::UnmarkUnsafePhis() { |
+ // No phis were collected. Nothing to do. |
+ if (phis_.length() == 0) return; |
+ |
+ // Worklist used to transitively clear kUint32 from phis that |
+ // are used as arguments to other phis. |
+ ZoneList<HPhi*> worklist(phis_.length(), zone()); |
+ |
+ // Phi can be used as a uint32 value if and only if |
+ // all its operands are uint32 values and all its |
+ // uses are uint32 safe. |
+ |
+ // Iterate over collected phis and unmark those that |
+ // are unsafe. When unmarking phi unmark its operands |
+ // and add it to the worklist if it is a phi as well. |
+ // Phis that are still marked as safe are shifted down |
+ // so that all safe phis form a prefix of the phis_ array. |
+ int phi_count = 0; |
+ for (int i = 0; i < phis_.length(); i++) { |
+ HPhi* phi = phis_[i]; |
+ |
+ if (CheckPhiOperands(phi) && Uint32UsesAreSafe(phi)) { |
+ phis_[phi_count++] = phi; |
+ } else { |
+ UnmarkPhi(phi, &worklist); |
+ } |
+ } |
+ |
+ // Now phis array contains only those phis that have safe |
+ // non-phi uses. Start transitively clearing kUint32 flag |
+ // from phi operands of discovered non-safe phis until |
+ // only safe phis are left. |
+ while (!worklist.is_empty()) { |
+ while (!worklist.is_empty()) { |
+ HPhi* phi = worklist.RemoveLast(); |
+ UnmarkPhi(phi, &worklist); |
+ } |
+ |
+ // Check if any operands to safe phis were unmarked |
+ // turning a safe phi into unsafe. The same value |
+ // can flow into several phis. |
+ int new_phi_count = 0; |
+ for (int i = 0; i < phi_count; i++) { |
+ HPhi* phi = phis_[i]; |
+ |
+ if (CheckPhiOperands(phi)) { |
+ phis_[new_phi_count++] = phi; |
+ } else { |
+ UnmarkPhi(phi, &worklist); |
+ } |
+ } |
+ phi_count = new_phi_count; |
+ } |
+} |
+ |
+ |
+void HUint32AnalysisPhase::Run() { |
+ if (!graph()->has_uint32_instructions()) return; |
+ |
+ ZoneList<HInstruction*>* uint32_instructions = graph()->uint32_instructions(); |
+ for (int i = 0; i < uint32_instructions->length(); ++i) { |
+ // Analyze instruction and mark it with kUint32 if all |
+ // its uses are uint32 safe. |
+ HInstruction* current = uint32_instructions->at(i); |
+ if (Uint32UsesAreSafe(current)) current->SetFlag(HInstruction::kUint32); |
+ } |
+ |
+ // Some phis might have been optimistically marked with kUint32 flag. |
+ // Remove this flag from those phis that are unsafe and propagate |
+ // this information transitively potentially clearing kUint32 flag |
+ // from some non-phi operations that are used as operands to unsafe phis. |
+ UnmarkUnsafePhis(); |
+} |
+ |
+ |
+} } // namespace v8::internal |