Turn UInt32 analysis into a proper HPhase.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 840abea86c1b5c6495207956d612717a3cced8be..d38c6f1a3c2df3f89db496c69a6e1f3b741771b8 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -37,6 +37,7 @@
 #include "hydrogen-escape-analysis.h"
 #include "hydrogen-infer-representation.h"
 #include "hydrogen-gvn.h"
+#include "hydrogen-uint32-analysis.h"
 #include "lithium-allocator.h"
 #include "parser.h"
 #include "scopeinfo.h"
@@ -3078,228 +3079,6 @@ void HGraph::MarkDeoptimizeOnUndefined() {
 }
 
 
-// Discover instructions that can be marked with kUint32 flag allowing
-// them to produce full range uint32 values.
-class Uint32Analysis BASE_EMBEDDED {
- public:
-  explicit Uint32Analysis(Zone* zone) : zone_(zone), phis_(4, zone) { }
-
-  void Analyze(HInstruction* current);
-
-  void UnmarkUnsafePhis();
-
- private:
-  bool IsSafeUint32Use(HValue* val, HValue* use);
-  bool Uint32UsesAreSafe(HValue* uint32val);
-  bool CheckPhiOperands(HPhi* phi);
-  void UnmarkPhi(HPhi* phi, ZoneList<HPhi*>* worklist);
-
-  Zone* zone_;
-  ZoneList<HPhi*> phis_;
-};
-
-
-bool Uint32Analysis::IsSafeUint32Use(HValue* val, HValue* use) {
-  // Operations that operatate 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 optimisitically treated as safe uint32 uses,
-// marked with kUint32 flag and collected in the phis_ list. A separate
-// path will be performed later by UnmarkUnsafePhis to clear kUint32 from
-// phis that are not actually uint32-safe (it requries fix point iteration).
-bool Uint32Analysis::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 phis 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 phis 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;
-}
-
-
-// Analyze instruction and mark it with kUint32 if all its uses are uint32
-// safe.
-void Uint32Analysis::Analyze(HInstruction* current) {
-  if (Uint32UsesAreSafe(current)) current->SetFlag(HInstruction::kUint32);
-}
-
-
-// Check if all operands to the given phi are marked with kUint32 flag.
-bool Uint32Analysis::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)) {
-      // Lazyly 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 Uint32Analysis::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 Uint32Analysis::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 phies until
-  // only safe phies are left.
-  while (!worklist.is_empty())  {
-    while (!worklist.is_empty()) {
-      HPhi* phi = worklist.RemoveLast();
-      UnmarkPhi(phi, &worklist);
-    }
-
-    // Check if any operands to safe phies 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 HGraph::ComputeSafeUint32Operations() {
-  HPhase phase("H_Compute safe UInt32 operations", this);
-  if (uint32_instructions_ == NULL) return;
-
-  Uint32Analysis analysis(zone());
-  for (int i = 0; i < uint32_instructions_->length(); ++i) {
-    HInstruction* current = uint32_instructions_->at(i);
-    if (current->IsLinked() && current->representation().IsInteger32()) {
-      analysis.Analyze(current);
-    }
-  }
-
-  // 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.
-  analysis.UnmarkUnsafePhis();
-}
-
-
 void HGraph::ComputeMinusZeroChecks() {
   HPhase phase("H_Compute minus zero checks", this);
   BitVector visited(GetMaximumValueID(), zone());
@@ -3811,7 +3590,7 @@ bool HGraph::Optimize(SmartArrayPointer<char>* bailout_reason) {
   // Must be performed before canonicalization to ensure that Canonicalize
   // will not remove semantically meaningful ToInt32 operations e.g. BIT_OR with
   // zero.
-  if (FLAG_opt_safe_uint32_operations) ComputeSafeUint32Operations();
+  if (FLAG_opt_safe_uint32_operations) Run<HUint32AnalysisPhase>();
 
   if (FLAG_use_canonicalizing) Canonicalize();