[Turbofan]: Eliminate the check for -0 if it's not possible/observable.

src/compiler/effect-control-linearizer.cc

 // Copyright 2015 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/compiler/effect-control-linearizer.h"
 
 #include "src/code-factory.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/linkage.h"
@@ skipping 1290 matching lines @@
 
   // Perform the actual unsigned integer modulus.
   Node* value = graph()->NewNode(machine()->Uint32Mod(), lhs, rhs, control);
 
   return ValueEffectControl(value, effect, control);
 }
 
 EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::LowerCheckedInt32Mul(Node* node, Node* frame_state,
                                               Node* effect, Node* control) {
+  CheckForMinusZeroMode mode = CheckMinusZeroModeOf(node->op());
   Node* zero = jsgraph()->Int32Constant(0);
   Node* lhs = node->InputAt(0);
   Node* rhs = node->InputAt(1);
 
   Node* projection =
       graph()->NewNode(machine()->Int32MulWithOverflow(), lhs, rhs, control);
 
   Node* check = graph()->NewNode(common()->Projection(1), projection, control);
   control = effect = graph()->NewNode(common()->DeoptimizeIf(), check,
                                       frame_state, effect, control);
 
   Node* value = graph()->NewNode(common()->Projection(0), projection, control);
 
-  Node* check_zero = graph()->NewNode(machine()->Word32Equal(), value, zero);
-  Node* branch_zero = graph()->NewNode(common()->Branch(BranchHint::kFalse),
-                                       check_zero, control);
+  if (mode == CheckForMinusZeroMode::kCheckForMinusZero) {
+    Node* check_zero = graph()->NewNode(machine()->Word32Equal(), value, zero);
+    Node* branch_zero = graph()->NewNode(common()->Branch(BranchHint::kFalse),
+                                         check_zero, control);
 
-  Node* if_zero = graph()->NewNode(common()->IfTrue(), branch_zero);
-  Node* e_if_zero = effect;
-  {
-    // We may need to return negative zero.
-    Node* or_inputs = graph()->NewNode(machine()->Word32Or(), lhs, rhs);
-    Node* check_or =
-        graph()->NewNode(machine()->Int32LessThan(), or_inputs, zero);
-    if_zero = e_if_zero = graph()->NewNode(common()->DeoptimizeIf(), check_or,
-                                           frame_state, e_if_zero, if_zero);
+    Node* if_zero = graph()->NewNode(common()->IfTrue(), branch_zero);
+    Node* e_if_zero = effect;
+    {
+      // We may need to return negative zero.
+      Node* or_inputs = graph()->NewNode(machine()->Word32Or(), lhs, rhs);
+      Node* check_or =
+          graph()->NewNode(machine()->Int32LessThan(), or_inputs, zero);
+      if_zero = e_if_zero = graph()->NewNode(common()->DeoptimizeIf(), check_or,
+                                             frame_state, e_if_zero, if_zero);
+    }
+
+    Node* if_not_zero = graph()->NewNode(common()->IfFalse(), branch_zero);
+    Node* e_if_not_zero = effect;
+
+    control = graph()->NewNode(common()->Merge(2), if_zero, if_not_zero);
+    effect = graph()->NewNode(common()->EffectPhi(2), e_if_zero, e_if_not_zero,
+                              control);
   }
 
-  Node* if_not_zero = graph()->NewNode(common()->IfFalse(), branch_zero);
-  Node* e_if_not_zero = effect;
-
-  control = graph()->NewNode(common()->Merge(2), if_zero, if_not_zero);
-  effect = graph()->NewNode(common()->EffectPhi(2), e_if_zero, e_if_not_zero,
-                            control);
-
   return ValueEffectControl(value, effect, control);
 }
 
 EffectControlLinearizer::ValueEffectControl
 EffectControlLinearizer::LowerCheckedUint32ToInt32(Node* node,
                                                    Node* frame_state,
                                                    Node* effect,
                                                    Node* control) {
   Node* value = node->InputAt(0);
   Node* max_int = jsgraph()->Int32Constant(std::numeric_limits<int32_t>::max());
@@ skipping 752 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoThrow);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8