Examples with ValueMapAnalysis com.jopdesign.jcopter.analysis.ValueMapAnalysis used on opensource projects

Example 1 with ValueMapAnalysis

use of com.jopdesign.jcopter.analysis.ValueMapAnalysis in project jop by jop-devel.

the class InlineHelper method needsNullpointerCheck.

/**
     * Check if an exception must be generated if the 'this' reference is null.
     * This test can return false if
     * <ul><li>There is no 'this' reference</li>
     * <li>The DFA analysis showed that the reference is never null</li>
     * <li>The inlined code will always generate an exception anyway</li>
     * <li>Generating checks has been disabled by configuration</li>
     * </ul>
     * <p>
     * The callstring does not need to start or to end at the method to optimize. However since the callstring is
     * used to check the DFA results if available, the callstring must match what the DFA expects, i.e. if
     * the DFA-results and -callstrings are updated during inlining, this callstring must not include inlined
     * invokes. Contrariwise if the DFA results are not updated during inline, the callstring must contain already
     * inlined invokes.
     * </p>
     *
     * @param callString The callstring including the invokesite of the invokee. The top invokesite does not need to
     *                   refer to an invoke instruction, and the referenced invoker method does not need to
     *                   be the method containing the invoke to inline (e.g. if the invoke to inline has
     *                   been inlined itself). However the callstring needs to match what the DFA expects.
     * @param invokee the devirtualized invokee.
     * @param analyzeCode if false, skip checking the code of the invokee.
     * @return true if a nullpointer check code should be generated.
     */
public boolean needsNullpointerCheck(CallString callString, MethodInfo invokee, boolean analyzeCode) {
    if (inlineConfig.skipNullpointerChecks())
        return false;
    InvokeSite invokeSite = callString.top();
    // check if we have a 'this' reference anyway
    if (invokeSite.isInvokeStatic() || invokeSite.isJVMCall()) {
        return false;
    }
    // TODO check the DFA results if available
    if (jcopter.useDFA()) {
    } else if ("<init>".equals(invokee.getShortName())) {
        // the NP check in this case (and hope that compilers for languages other than Java do the same..)
        return false;
    }
    if (!analyzeCode) {
        return true;
    }
    // check if the code will always throw an exception anyway (without producing any side effects before throwing)
    ValueMapAnalysis analysis = new ValueMapAnalysis(invokee);
    analysis.loadParameters();
    InstructionList list = invokee.getCode().getInstructionList(true, false);
    for (InstructionHandle ih : list.getInstructionHandles()) {
        Instruction instr = ih.getInstruction();
        if (instr instanceof ConstantPushInstruction || instr instanceof LocalVariableInstruction) {
            analysis.transfer(instr);
        } else if (instr instanceof GETFIELD || instr instanceof PUTFIELD || instr instanceof INVOKEVIRTUAL || instr instanceof INVOKEINTERFACE || instr instanceof INVOKESPECIAL) {
            int down = instr.consumeStack(invokee.getConstantPoolGen());
            ValueInfo value = analysis.getValueTable().top(down);
            // the same way as the inlined invoke
            if (value.isThisReference()) {
                return false;
            }
            break;
        } else {
            // we ignore all other instructions (for now..)
            break;
        }
    }
    return true;
}

Example 2 with ValueMapAnalysis

use of com.jopdesign.jcopter.analysis.ValueMapAnalysis in project jop by jop-devel.

the class SimpleInliner method analyzeInvokee.

/**
     * @param cs the callstring from the invoker to the invoke to inline (if recursive). Used to check DFA results.
     * @param invokee the invoked method to analyze
     * @param inlineData the map to populate with the parameters and the instructions to inline.
     * @return true if inlining is possible
     */
private boolean analyzeInvokee(CallString cs, MethodInfo invokee, InlineData inlineData) {
    // we allow loading of parameters, loading of constants, some instruction, and a return
    ValueMapAnalysis values = new ValueMapAnalysis(invokee);
    values.loadParameters();
    InstructionList il = invokee.getCode().getInstructionList(true, false);
    InstructionHandle ih = il.getStart();
    // we should at least have a return instruction, so even for empty methods we should fall through
    // generate the parameter mapping
    int count = 0;
    while (true) {
        Instruction instruction = ih.getInstruction();
        if (instruction instanceof PushInstruction || instruction instanceof NOP) {
            values.transfer(instruction);
            ih = ih.getNext();
            count++;
        } else {
            break;
        }
    }
    // store the mapping
    for (ValueInfo value : values.getValueTable().getStack()) {
        inlineData.addParam(value);
    }
    inlineData.setInlineStart(count);
    // if we do not need an NP check, we can also inline code which does not throw an exception in the same way
    boolean needsNPCheck = helper.needsNullpointerCheck(cs, invokee, false);
    boolean hasNPCheck = false;
    // we allow up to 5 instructions and one return before assuming that the resulting code will be too large
    for (int i = 0; i < 6; i++) {
        // now lets see what we have here as non-push instructions
        Instruction instruction = ih.getInstruction();
        if (instruction instanceof InvokeInstruction) {
            if (inlineData.getInvokeSite() != null) {
                // only inline at most one invoke
                return false;
            }
            InvokeSite is = invokee.getCode().getInvokeSite(ih);
            inlineData.setInvokeSite(is);
            hasNPCheck |= !is.isInvokeStatic();
        } else if (instruction instanceof FieldInstruction) {
            if (instruction instanceof GETFIELD) {
                hasNPCheck |= values.getValueTable().top().isThisReference();
            }
            if (instruction instanceof PUTFIELD) {
                int down = values.getValueTable().top().isContinued() ? 2 : 1;
                hasNPCheck |= values.getValueTable().top(down).isThisReference();
            }
        } else if (instruction instanceof ArithmeticInstruction || instruction instanceof ConversionInstruction || instruction instanceof StackInstruction || instruction instanceof LDC || instruction instanceof LDC2_W || instruction instanceof ARRAYLENGTH || instruction instanceof CHECKCAST || instruction instanceof NOP) {
        // nothing to do, just copy them
        } else if (instruction instanceof ReturnInstruction) {
            if (needsNPCheck && !hasNPCheck) {
                // We were nearly finished.. but NP check test failed
                this.requiresNPCheck++;
                if (logger.isTraceEnabled()) {
                    logger.trace("Not inlining " + invokee + " because it requires a NP check.");
                }
                return false;
            }
            // else we need to add pop instructions
            if (instruction instanceof RETURN) {
                // we do not return anything, so we must empty the stack
                while (values.getValueTable().getStackSize() > 0) {
                    Instruction pop;
                    if (values.getValueTable().top().isContinued()) {
                        pop = new POP2();
                    } else {
                        pop = new POP();
                    }
                    inlineData.addEpilogue(pop);
                    values.transfer(pop);
                }
                return true;
            } else {
                Type type = ((ReturnInstruction) instruction).getType();
                // javac anyway)
                return values.getValueTable().getStackSize() == type.getSize();
            }
        } else {
            // if we encounter an instruction which we do not handle, we do not inline
            unhandledInstructions++;
            if (logger.isTraceEnabled()) {
                logger.trace("Not inlining " + invokee + " because of unhandled instruction " + instruction.toString(invokee.getClassInfo().getConstantPoolGen().getConstantPool()));
            }
            return false;
        }
        // update the stack map since we need it to handle RETURN
        values.transfer(instruction);
        ih = ih.getNext();
    }
    // too many instructions, do not inline
    return false;
}