hg: nashorn/jdk8/nashorn: 8026137: Fix Issues with Binary Evaluation Order

[Hannes Wallnoefer]

Side effects can still occur with primitive types. As an example, this 
script from the test case as a numeric right hand side:

({valueOf: function(){throw 0}}) - ({valueOf: function(){throw 1}} - 1)

But maybe something like this (pseudo-code) could work in 
CodeGenerator#safeLiteral:

   isPrimitiveLiteralNode || (isIdentNode && isPrimitiveType)

An IdentNode can have side effects if it is a global with a getter, but 
if we know it's type that shouldn't be the case.

Hannes

Am 2013-10-09 18:44, schrieb André Bargull:
> Quick question for this change set:
>
> Why does CodeGenerator#safeLiteral(...) need to test for literal nodes 
> instead of using type information? When the right-hand-side is a 
> primitive type, side effects cannot occur, so the additional 
> swap/dup/pop instructions can be omitted safely.
>
> For example `function f(a){var c = 1; return a - c }` now emits:
>     ALOAD 1
>     ILOAD 4
>     SWAP
>     INVOKESTATIC jdk/nashorn/internal/runtime/JSType.toNumber 
> (Ljava/lang/Object;)D
>     DUP2_X1
>     POP2
>     I2D
>     DSUB
>
> Using type info it's possible to change the bytecode to:
>     ALOAD 1
>     INVOKESTATIC jdk/nashorn/internal/runtime/JSType.toNumber 
> (Ljava/lang/Object;)D
>     ILOAD 4
>     I2D
>     DSUB
>
>
> (Also: That was one of the bug reports which worried me a bit, because 
> I expected the changes to be non-trivial. :-(
>
>
> - André
>
>> Changeset: 03a68e7ca1d5
>> Author:    lagergren
>> Date:      2013-10-09 17:53 +0200
>> URL:http://hg.openjdk.java.net/nashorn/jdk8/nashorn/rev/03a68e7ca1d5
>>
>> 8026137: Fix Issues with Binary Evaluation Order
>> Reviewed-by: hannesw, jlaskey
>> Contributed-by:marcus.lagergren at oracle.com 
>> <http://mail.openjdk.java.net/mailman/listinfo/nashorn-dev>,attila.szegedi 
>> at oracle.com 
>> <http://mail.openjdk.java.net/mailman/listinfo/nashorn-dev>
>>
>> ! src/jdk/nashorn/internal/codegen/Attr.java
>> ! src/jdk/nashorn/internal/codegen/BranchOptimizer.java
>> ! src/jdk/nashorn/internal/codegen/CodeGenerator.java
>> ! src/jdk/nashorn/internal/codegen/CompileUnit.java
>> ! src/jdk/nashorn/internal/codegen/Compiler.java
>> ! src/jdk/nashorn/internal/codegen/FinalizeTypes.java
>> ! src/jdk/nashorn/internal/codegen/MethodEmitter.java
>> ! src/jdk/nashorn/internal/codegen/WeighNodes.java
>> ! src/jdk/nashorn/internal/codegen/types/BooleanType.java
>> ! src/jdk/nashorn/internal/codegen/types/ObjectType.java
>> ! src/jdk/nashorn/internal/codegen/types/Type.java
>> ! src/jdk/nashorn/internal/ir/AccessNode.java
>> ! src/jdk/nashorn/internal/ir/BaseNode.java
>> ! src/jdk/nashorn/internal/ir/CallNode.java
>> ! src/jdk/nashorn/internal/ir/IdentNode.java
>> ! src/jdk/nashorn/internal/ir/IndexNode.java
>> ! src/jdk/nashorn/internal/ir/LiteralNode.java
>> ! src/jdk/nashorn/internal/ir/RuntimeNode.java
>> - src/jdk/nashorn/internal/ir/TypeOverride.java
>> ! src/jdk/nashorn/internal/ir/UnaryNode.java
>> ! src/jdk/nashorn/internal/ir/visitor/NodeOperatorVisitor.java
>> ! src/jdk/nashorn/internal/parser/TokenType.java
>> ! src/jdk/nashorn/internal/runtime/Context.java
>> ! src/jdk/nashorn/internal/runtime/JSType.java
>> ! src/jdk/nashorn/internal/runtime/arrays/JavaArrayIterator.java
>> ! src/jdk/nashorn/internal/runtime/arrays/ReverseJavaArrayIterator.java
>> ! src/jdk/nashorn/internal/runtime/linker/JSObjectLinker.java
>> + test/script/basic/JDK-8026137.js
>> + test/script/basic/JDK-8026137.js.EXPECTED