I am trying to write a timing strategy for Volta, an execution time analyzer for Java processors. In Volta, the execution time of a Java Bytecode instruction is determined with the following method:
public int getCycles(Instruction instruction)
This method looks up the instruction time of the Instruction. The class Instruction of BCEL is used: Instruction (http://commons.apache.org/bcel/apidocs/org/apache/bcel/generic/Instruction.html?is-external=true
For example, getCycles(BIPUSH) returns "2", meaning it takes 2 cycles on a java processor to execute a bipush bytecode.
Okay, now the problem. On a particular Java processor, the execution time of the instruction varies with the argument. For example, using LDC to load an integer takes 7 cycles. Using LDC to load a string takes 3 cycles.
Therefore, I need to know exactly what an Instruction does, just the opcode isn't enough. Does anybody know how to do this? I might be able to get the index used by the LDC instruction with
but how can I determine which constant is actually loaded?