RFR(XS): 8143127: InvokerBytecodeGenerator emitConst should handle Byte, Short, Character

[Claes Redestad]

On 2015-11-18 23:26, Aleksey Shipilev wrote:
> By the way, I see there is a cleaner way to implement emitIconstInsn,
> see java.lang.invoke.TypeConvertingMethodAdapter.iconst:
>
>      void iconst(final int cst) {
>          if (cst >= -1 && cst <= 5) {
>              mv.visitInsn(Opcodes.ICONST_0 + cst);
>          } else if (cst >= Byte.MIN_VALUE && cst <= Byte.MAX_VALUE) {
>              mv.visitIntInsn(Opcodes.BIPUSH, cst);
>          } else if (cst >= Short.MIN_VALUE && cst <= Short.MAX_VALUE) {
>              mv.visitIntInsn(Opcodes.SIPUSH, cst);
>          } else {
>              mv.visitLdcInsn(cst);
>          }
>      }
>
> http://hg.openjdk.java.net/jdk9/dev/jdk/file/aa9e8b3916ae/src/java.base/share/classes/java/lang/invoke/TypeConvertingMethodAdapter.java#l285
>

Nice catch.

Picking up this tiny improvement again, I realized there are a few other 
bytecode minifying tricks we could consider while we're at it:

http://cr.openjdk.java.net/~redestad/8143127/webrev.02/

It would probably make sense to move emitConst to 
TypeConvertingMethodAdapter and use that in place a raw MethodVisitor - 
removing some code - but there might be some reasons not to 
(bootstrapping?). For this improvement I opt to keep the changes 
contained inside InvokerBytecodeGenerator. unless someone insists.

/Claes