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

[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