Consistently assume that arithmetic operations can overflow unless one can prove the opposite.

src/hydrogen-instructions.cc

 // Copyright 2012 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
@@ skipping 1427 matching lines @@
 }
 
 
 HValue* HMul::Canonicalize() {
   if (IsIdentityOperation(left(), right(), 1)) return left();
   if (IsIdentityOperation(right(), left(), 1)) return right();
   return this;
 }
 
 
+HValue* HMod::Canonicalize() {
+  return this;
+}
+
+
+HValue* HDiv::Canonicalize() {
+  return this;
+}
+
+
 HValue* HChange::Canonicalize() {
   return (from().Equals(to())) ? value() : this;
 }
 
 
 HValue* HWrapReceiver::Canonicalize() {
   if (HasNoUses()) return NULL;
   if (receiver()->type().IsJSObject()) {
     return receiver();
   }
@@ skipping 308 matching lines @@
     res->set_can_be_minus_zero(m0);
     return res;
   } else {
     return HValue::InferRange(zone);
   }
 }
 
 
 Range* HDiv::InferRange(Zone* zone) {
   if (representation().IsInteger32()) {
+    Range* a = left()->range();
+    Range* b = right()->range();
     Range* result = new(zone) Range();
-    if (left()->range()->CanBeMinusZero()) {
+    if (a->CanBeMinusZero()) {
       result->set_can_be_minus_zero(true);
     }
 
-    if (left()->range()->CanBeZero() && right()->range()->CanBeNegative()) {
+    if (a->CanBeZero() && b->CanBeNegative()) {
       result->set_can_be_minus_zero(true);
     }
 
-    if (right()->range()->Includes(-1) && left()->range()->Includes(kMinInt)) {
-      SetFlag(HValue::kCanOverflow);
+    if (!a->Includes(kMinInt) || !b->Includes(-1)) {
+      ClearFlag(HValue::kCanOverflow);
     }
 
-    if (!right()->range()->CanBeZero()) {
+    if (!b->CanBeZero()) {
       ClearFlag(HValue::kCanBeDivByZero);
     }
     return result;
   } else {
     return HValue::InferRange(zone);
   }
 }
 
 
 Range* HMod::InferRange(Zone* zone) {
   if (representation().IsInteger32()) {
     Range* a = left()->range();
+    Range* b = right()->range();
     Range* result = new(zone) Range();
     if (a->CanBeMinusZero() || a->CanBeNegative()) {
       result->set_can_be_minus_zero(true);
     }
 
-    if (right()->range()->Includes(-1) && left()->range()->Includes(kMinInt)) {
-      SetFlag(HValue::kCanOverflow);
+    if (!a->Includes(kMinInt) || !b->Includes(-1)) {
+      ClearFlag(HValue::kCanOverflow);
     }
 
-    if (!right()->range()->CanBeZero()) {
+    if (!b->CanBeZero()) {
       ClearFlag(HValue::kCanBeDivByZero);
     }
     return result;
   } else {
     return HValue::InferRange(zone);
   }
 }
 
 
 void HPhi::AddInformativeDefinitions() {
@@ skipping 1830 matching lines @@
 
 
 void HCheckFunction::Verify() {
   HInstruction::Verify();
   ASSERT(HasNoUses());
 }
 
 #endif
 
 } }  // namespace v8::internal