Turn range analysis into proper HPhase.

src/hydrogen-range-analysis.cc

+// 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-range-analysis.h"
+
+namespace v8 {
+namespace internal {
+
+
+void HRangeAnalysisPhase::TraceRange(const char* msg, ...) {
+  if (FLAG_trace_range) {
+    va_list arguments;
+    va_start(arguments, msg);
+    OS::VPrint(msg, arguments);
+    va_end(arguments);
+  }
+}
+
+
+void HRangeAnalysisPhase::Analyze(HBasicBlock* block) {
+  TraceRange("Analyzing block B%d\n", block->block_id());
+
+  int last_changed_range = changed_ranges_.length() - 1;
+
+  // Infer range based on control flow.
+  if (block->predecessors()->length() == 1) {
+    HBasicBlock* pred = block->predecessors()->first();
+    if (pred->end()->IsCompareIDAndBranch()) {
+      InferControlFlowRange(HCompareIDAndBranch::cast(pred->end()), block);
+    }
+  }
+
+  // Process phi instructions.
+  for (int i = 0; i < block->phis()->length(); ++i) {
+    HPhi* phi = block->phis()->at(i);
+    InferRange(phi);
+  }
+
+  // Go through all instructions of the current block.
+  for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
+    InferRange(it.Current());
+  }
+
+  // Continue analysis in all dominated blocks.
+  for (int i = 0; i < block->dominated_blocks()->length(); ++i) {
+    Analyze(block->dominated_blocks()->at(i));
+  }
+
+  RollBackTo(last_changed_range);
+}
+
+
+void HRangeAnalysisPhase::InferControlFlowRange(HCompareIDAndBranch* test,
+                                                HBasicBlock* dest) {
+  ASSERT((test->FirstSuccessor() == dest) == (test->SecondSuccessor() != dest));
+  if (test->representation().IsSmiOrInteger32()) {
+    Token::Value op = test->token();
+    if (test->SecondSuccessor() == dest) {
+      op = Token::NegateCompareOp(op);
+    }
+    Token::Value inverted_op = Token::ReverseCompareOp(op);
+    UpdateControlFlowRange(op, test->left(), test->right());
+    UpdateControlFlowRange(inverted_op, test->right(), test->left());
+  }
+}
+
+
+// We know that value [op] other. Use this information to update the range on
+// value.
+void HRangeAnalysisPhase::UpdateControlFlowRange(Token::Value op,
+                                                 HValue* value,
+                                                 HValue* other) {
+  Range temp_range;
+  Range* range = other->range() != NULL ? other->range() : &temp_range;
+  Range* new_range = NULL;
+
+  TraceRange("Control flow range infer %d %s %d\n",
+             value->id(),
+             Token::Name(op),
+             other->id());
+
+  if (op == Token::EQ || op == Token::EQ_STRICT) {
+    // The same range has to apply for value.
+    new_range = range->Copy(graph()->zone());
+  } else if (op == Token::LT || op == Token::LTE) {
+    new_range = range->CopyClearLower(graph()->zone());
+    if (op == Token::LT) {
+      new_range->AddConstant(-1);
+    }
+  } else if (op == Token::GT || op == Token::GTE) {
+    new_range = range->CopyClearUpper(graph()->zone());
+    if (op == Token::GT) {
+      new_range->AddConstant(1);
+    }
+  }
+
+  if (new_range != NULL && !new_range->IsMostGeneric()) {
+    AddRange(value, new_range);
+  }
+}
+
+
+void HRangeAnalysisPhase::InferRange(HValue* value) {
+  ASSERT(!value->HasRange());
+  if (!value->representation().IsNone()) {
+    value->ComputeInitialRange(graph()->zone());
+    Range* range = value->range();
+    TraceRange("Initial inferred range of %d (%s) set to [%d,%d]\n",
+               value->id(),
+               value->Mnemonic(),
+               range->lower(),
+               range->upper());
+  }
+}
+
+
+void HRangeAnalysisPhase::RollBackTo(int index) {
+  for (int i = index + 1; i < changed_ranges_.length(); ++i) {
+    changed_ranges_[i]->RemoveLastAddedRange();
+  }
+  changed_ranges_.Rewind(index + 1);
+}
+
+
+void HRangeAnalysisPhase::AddRange(HValue* value, Range* range) {
+  Range* original_range = value->range();
+  value->AddNewRange(range, graph()->zone());
+  changed_ranges_.Add(value, zone());
+  Range* new_range = value->range();
+  TraceRange("Updated range of %d set to [%d,%d]\n",
+             value->id(),
+             new_range->lower(),
+             new_range->upper());
+  if (original_range != NULL) {
+    TraceRange("Original range was [%d,%d]\n",
+               original_range->lower(),
+               original_range->upper());
+  }
+  TraceRange("New information was [%d,%d]\n",
+             range->lower(),
+             range->upper());
+}
+
+
+} }  // namespace v8::internal