Revision: 15934
Author: [email protected]
Date: Mon Jul 29 05:35:43 2013
Log: Fix IsDeletable() for HStringAdd, HStringCharCodeAt,
HStringCharFromCode.
BUG=
[email protected], [email protected]
Review URL: https://codereview.chromium.org/20241005
http://code.google.com/p/v8/source/detail?r=15934
Added:
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-add-warm.js
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-add.js
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-code-at.js
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-code-at2.js
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-from-code.js
Modified:
/branches/bleeding_edge/src/hydrogen-instructions.cc
/branches/bleeding_edge/src/hydrogen-instructions.h
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/compiler/dead-string-add-warm.js
Mon Jul 29 05:35:43 2013
@@ -0,0 +1,76 @@
+// 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.
+
+// Flags: --allow-natives-syntax
+
+function dead1(a, b) {
+ var x = "a" + "b";
+ return a; // x, "a", and "b" are dead code
+}
+
+function dead2(a, b) {
+ var x = "0" + a;
+ var y = "0" + b;
+ return a; // x and y are both dead
+}
+
+function dead3(a, b) {
+ a = a ? "1" : "0";
+ b = b ? "1" : "0";
+ var x = a + "0";
+ var y = b + "0";
+ return a; // x and y are both dead
+}
+
+function run() {
+ assertEquals(33, dead1(33, 32));
+ assertEquals(33, dead2(33, 32));
+ assertEquals("1", dead3(33, 32));
+
+ assertEquals(31, dead1(31, 30));
+ assertEquals(31, dead2(31, 30));
+ assertEquals("1", dead3(31, 32));
+
+ assertEquals(0, dead1(0, 30));
+ assertEquals(0, dead2(0, 30));
+ assertEquals("0", dead3(0, 32));
+
+ assertEquals(true, dead1(true, 0));
+ assertEquals(true, dead2(true, 0));
+ assertEquals("1", dead3(true, 0));
+
+ assertEquals("true", dead1("true", 0));
+ assertEquals("true", dead2("true", 0));
+ assertEquals("1", dead3("true", 0));
+}
+
+run();
+run();
+%OptimizeFunctionOnNextCall(dead1);
+%OptimizeFunctionOnNextCall(dead2);
+%OptimizeFunctionOnNextCall(dead3);
+run();
=======================================
--- /dev/null
+++ /branches/bleeding_edge/test/mjsunit/compiler/dead-string-add.js Mon
Jul 29 05:35:43 2013
@@ -0,0 +1,65 @@
+// 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.
+
+function dead1(a, b) {
+ var x = "a" + "b";
+ return a; // x, "a", and "b" are dead code
+}
+
+function dead2(a, b) {
+ var x = a + "0";
+ var y = b + "0";
+ return a; // x and y are both dead
+}
+
+function dead3(a, b) {
+ a = a ? "1" : "0";
+ b = b ? "1" : "0";
+ var x = a + "0";
+ var y = b + "0";
+ return a; // x and y are both dead
+}
+
+assertEquals(33, dead1(33, 32));
+assertEquals(33, dead2(33, 32));
+assertEquals("1", dead3(33, 32));
+
+assertEquals(31, dead1(31, 30));
+assertEquals(31, dead2(31, 30));
+assertEquals("1", dead3(31, 32));
+
+assertEquals(0, dead1(0, 30));
+assertEquals(0, dead2(0, 30));
+assertEquals("0", dead3(0, 32));
+
+assertEquals(true, dead1(true, 0));
+assertEquals(true, dead2(true, 0));
+assertEquals("1", dead3(true, 0));
+
+assertEquals("true", dead1("true", 0));
+assertEquals("true", dead2("true", 0));
+assertEquals("1", dead3("true", 0));
=======================================
--- /dev/null
+++
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-code-at.js
Mon Jul 29 05:35:43 2013
@@ -0,0 +1,81 @@
+// 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.
+
+// Flags: --allow-natives-syntax
+
+var S1 = "string1";
+var S2 = "@@string2";
+
+function dead1(a, b) {
+ var x = %StringCharCodeAt(a, 4);
+ return a; // x is dead code
+}
+
+function dead2(a, b) {
+ var x = %StringCharCodeAt(a, 3);
+ var y = %StringCharCodeAt(b, 1);
+ return a; // x and y are both dead
+}
+
+function dead3(a, b) {
+ a = a ? "11" : "12";
+ b = b ? "13" : "14";
+ var x = %StringCharCodeAt(a, 2);
+ var y = %StringCharCodeAt(b, 0);
+ return a; // x and y are both dead
+}
+
+function test() {
+ var S3 = S1 + S2;
+
+ assertEquals(S1, dead1(S1, S2));
+ assertEquals(S1, dead2(S1, S2));
+ assertEquals("11", dead3(S1, S2));
+
+ assertEquals(S2, dead1(S2, 677));
+ assertEquals(S2, dead2(S2, S3));
+ assertEquals("11", dead3(S2, S3));
+
+ assertEquals(S3, dead1(S3, 399));
+ assertEquals(S3, dead2(S3, "false"));
+ assertEquals("12", dead3(0, 32));
+
+ assertEquals(S3, dead1(S3, 0));
+ assertEquals(S3, dead2(S3, S1));
+ assertEquals("11", dead3(S3, 0));
+
+ assertEquals("true", dead1("true", 0));
+ assertEquals("true", dead2("true", S3));
+ assertEquals("11", dead3("true", 0));
+}
+
+test();
+test();
+%OptimizeFunctionOnNextCall(dead1);
+%OptimizeFunctionOnNextCall(dead2);
+%OptimizeFunctionOnNextCall(dead3);
+test();
=======================================
--- /dev/null
+++
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-code-at2.js
Mon Jul 29 05:35:43 2013
@@ -0,0 +1,81 @@
+// 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.
+
+// Flags: --allow-natives-syntax
+
+var S1 = "string1";
+var S2 = "@@string2";
+
+function dead1(a, b) {
+ var x = %_StringCharCodeAt(a, 4);
+ return a; // x is dead code
+}
+
+function dead2(a, b) {
+ var x = %_StringCharCodeAt(a, 3);
+ var y = %_StringCharCodeAt(b, 1);
+ return a; // x and y are both dead
+}
+
+function dead3(a, b) {
+ a = a ? "11" : "12";
+ b = b ? "13" : "14";
+ var x = %_StringCharCodeAt(a, 2);
+ var y = %_StringCharCodeAt(b, 0);
+ return a; // x and y are both dead
+}
+
+function test() {
+ var S3 = S1 + S2;
+
+ assertEquals(S1, dead1(S1, S2));
+ assertEquals(S1, dead2(S1, S2));
+ assertEquals("11", dead3(S1, S2));
+
+ assertEquals(S2, dead1(S2, 677));
+ assertEquals(S2, dead2(S2, S3));
+ assertEquals("11", dead3(S2, S3));
+
+ assertEquals(S3, dead1(S3, 399));
+ assertEquals(S3, dead2(S3, "false"));
+ assertEquals("12", dead3(0, 32));
+
+ assertEquals(S3, dead1(S3, 0));
+ assertEquals(S3, dead2(S3, S1));
+ assertEquals("11", dead3(S3, 0));
+
+ assertEquals("true", dead1("true", 0));
+ assertEquals("true", dead2("true", S3));
+ assertEquals("11", dead3("true", 0));
+}
+
+test();
+test();
+%OptimizeFunctionOnNextCall(dead1);
+%OptimizeFunctionOnNextCall(dead2);
+%OptimizeFunctionOnNextCall(dead3);
+test();
=======================================
--- /dev/null
+++
/branches/bleeding_edge/test/mjsunit/compiler/dead-string-char-from-code.js
Mon Jul 29 05:35:43 2013
@@ -0,0 +1,76 @@
+// 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.
+
+// Flags: --allow-natives-syntax
+
+function dead1(a, b) {
+ var x = %_StringCharFromCode(a);
+ return a; // x is dead code
+}
+
+function dead2(a, b) {
+ var x = %_StringCharFromCode(a);
+ var y = %_StringCharFromCode(b);
+ return a; // x and y are both dead
+}
+
+function dead3(a, b) {
+ a = a ? 11 : 12;
+ b = b ? 13 : 14;
+ var x = %_StringCharFromCode(a);
+ var y = %_StringCharFromCode(b);
+ return a; // x and y are both dead
+}
+
+function test() {
+ assertEquals(33, dead1(33, 32));
+ assertEquals(33, dead2(33, 32));
+ assertEquals(11, dead3(33, 32));
+
+ assertEquals(31, dead1(31, 30));
+ assertEquals(31, dead2(31, 30));
+ assertEquals(11, dead3(31, 32));
+
+ assertEquals(0, dead1(0, 30));
+ assertEquals(0, dead2(0, 30));
+ assertEquals(12, dead3(0, 32));
+
+ assertEquals(true, dead1(true, 0));
+ assertEquals(true, dead2(true, 0));
+ assertEquals(11, dead3(true, 0));
+
+ assertEquals("true", dead1("true", 0));
+ assertEquals("true", dead2("true", 0));
+ assertEquals(11, dead3("true", 0));
+}
+
+test();
+test();
+%OptimizeFunctionOnNextCall(dead1);
+%OptimizeFunctionOnNextCall(dead2);
+%OptimizeFunctionOnNextCall(dead3);
+test();
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.cc Mon Jul 29
02:42:57 2013
+++ /branches/bleeding_edge/src/hydrogen-instructions.cc Mon Jul 29
05:35:43 2013
@@ -3716,11 +3716,6 @@
if (!input_rep.IsTagged()) rep = rep.generalize(input_rep);
return rep;
}
-
-
-HType HStringCharFromCode::CalculateInferredType() {
- return HType::String();
-}
void HAllocate::HandleSideEffectDominator(GVNFlag side_effect,
=======================================
--- /branches/bleeding_edge/src/hydrogen-instructions.h Mon Jul 29 04:50:39
2013
+++ /branches/bleeding_edge/src/hydrogen-instructions.h Mon Jul 29 05:35:43
2013
@@ -422,6 +422,24 @@
bool IsHeapObject() const {
return IsHeapNumber() || IsString() || IsBoolean() || IsNonPrimitive();
}
+
+ bool ToStringOrToNumberCanBeObserved(Representation representation) {
+ switch (type_) {
+ case kTaggedPrimitive: // fallthru
+ case kTaggedNumber: // fallthru
+ case kSmi: // fallthru
+ case kHeapNumber: // fallthru
+ case kString: // fallthru
+ case kBoolean:
+ return false;
+ case kJSArray: // fallthru
+ case kJSObject:
+ return true;
+ case kTagged:
+ break;
+ }
+ return !representation.IsSmiOrInteger32()
&& !representation.IsDouble();
+ }
static HType TypeFromValue(Handle<Object> value);
@@ -1125,6 +1143,18 @@
return false;
}
}
+
+ // Returns true conservatively if the program might be able to observe a
+ // ToString() operation on this value.
+ bool ToStringCanBeObserved() const {
+ return type().ToStringOrToNumberCanBeObserved(representation());
+ }
+
+ // Returns true conservatively if the program might be able to observe a
+ // ToNumber() operation on this value.
+ bool ToNumberCanBeObserved() const {
+ return type().ToStringOrToNumberCanBeObserved(representation());
+ }
protected:
void TryGuaranteeRangeRecursive(RangeEvaluationContext* context);
@@ -3319,9 +3349,6 @@
virtual Opcode opcode() const { return HValue::kPhi; }
void SimplifyConstantInputs();
-
- // TODO(titzer): we can't eliminate the receiver for generating
backtraces
- virtual bool IsDeletable() const { return !IsReceiver(); }
protected:
virtual void DeleteFromGraph();
@@ -3342,6 +3369,9 @@
int indirect_uses_[Representation::kNumRepresentations];
int phi_id_;
InductionVariableData* induction_variable_data_;
+
+ // TODO(titzer): we can't eliminate the receiver for generating
backtraces
+ virtual bool IsDeletable() const { return !IsReceiver(); }
};
@@ -3653,9 +3683,9 @@
observed_input_representation_[1] = Representation::None();
}
- HValue* context() { return OperandAt(0); }
- HValue* left() { return OperandAt(1); }
- HValue* right() { return OperandAt(2); }
+ HValue* context() const { return OperandAt(0); }
+ HValue* left() const { return OperandAt(1); }
+ HValue* right() const { return OperandAt(2); }
// True if switching left and right operands likely generates better
code.
bool AreOperandsBetterSwitched() {
@@ -3909,9 +3939,6 @@
virtual Representation RequiredInputRepresentation(int arg_index) {
return representation();
}
- virtual bool IsDeletable() const {
- return skip_check() && !FLAG_debug_code;
- }
virtual bool IsRelationTrueInternal(NumericRelation relation,
HValue* related_value,
@@ -3948,6 +3975,11 @@
int scale_;
RangeGuaranteeDirection responsibility_direction_;
bool allow_equality_;
+
+ private:
+ virtual bool IsDeletable() const {
+ return skip_check() && !FLAG_debug_code;
+ }
};
@@ -6451,8 +6483,9 @@
SetGVNFlag(kChangesNewSpacePromotion);
}
- // TODO(svenpanne) Might be safe, but leave it out until we know for
sure.
- // virtual bool IsDeletable() const { return true; }
+ // No side-effects except possible allocation.
+ // NOTE: this instruction _does not_ call ToString() on its inputs.
+ virtual bool IsDeletable() const { return true; }
const StringAddFlags flags_;
};
@@ -6477,9 +6510,9 @@
: Representation::Tagged();
}
- HValue* context() { return OperandAt(0); }
- HValue* string() { return OperandAt(1); }
- HValue* index() { return OperandAt(2); }
+ HValue* context() const { return OperandAt(0); }
+ HValue* string() const { return OperandAt(1); }
+ HValue* index() const { return OperandAt(2); }
DECLARE_CONCRETE_INSTRUCTION(StringCharCodeAt)
@@ -6490,9 +6523,9 @@
return new(zone) Range(0, String::kMaxUtf16CodeUnit);
}
- // TODO(svenpanne) Might be safe, but leave it out until we know for
sure.
- // private:
- // virtual bool IsDeletable() const { return true; }
+ private:
+ // No side effects: runtime function assumes string + number inputs.
+ virtual bool IsDeletable() const { return true; }
};
@@ -6507,10 +6540,10 @@
? Representation::Tagged()
: Representation::Integer32();
}
- virtual HType CalculateInferredType();
+ virtual HType CalculateInferredType() { return HType::String(); }
- HValue* context() { return OperandAt(0); }
- HValue* value() { return OperandAt(1); }
+ HValue* context() const { return OperandAt(0); }
+ HValue* value() const { return OperandAt(1); }
virtual bool DataEquals(HValue* other) { return true; }
@@ -6525,8 +6558,9 @@
SetGVNFlag(kChangesNewSpacePromotion);
}
- // TODO(svenpanne) Might be safe, but leave it out until we know for
sure.
- // virtual bool IsDeletable() const { return true; }
+ virtual bool IsDeletable() const {
+ return !value()->ToNumberCanBeObserved();
+ }
};
--
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