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jode/jode/jode/flow/MarkInlineExpression.java

116 lines
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/*
* MarkInlineExpression (c) 1998 Jochen Hoenicke
*
* You may distribute under the terms of the GNU General Public License.
*
* IN NO EVENT SHALL JOCHEN HOENICKE BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF
* THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF JOCHEN HOENICKE
* HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* JOCHEN HOENICKE SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
* BASIS, AND JOCHEN HOENICKE HAS NO OBLIGATION TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*
* $Id$
*/
package jode.flow;
import jode.Decompiler;
import jode.decompiler.*;
/**
* This handles inline methods. When you compile with -O flag javac will
* inline methods that are static, final or private (i.e. non virtual).
* The parameters may be stored in locals, before inlining the body of the
* method.
*
* Inlined methods look as follows:
*
* local_1 = expr_1
* local_2 = expr_2
* [PUSH ]expr(local_1,local_2,constants...)
*
* where local_1 and local_2 aren't used any more.
*
* If later one finds a reuse of local_x, the inline transformation
* must be reverted: If there is no surrounding expression, the locals
* are moved to initializers around; otherwise if the locals are used
* in the expression or a super expression, they are combined with the
* next occurence; otherwise the locals are moved behind the next expression.
* This doesn't care for side effects though :-(
*
* There are many other reasons why a part could look like this; only
* if a matching method is found, that does exactly this (or if the
* options createInlines is given), we may call this method.
*
* As long as inlines are not supported, if the local is never used, it
* is simply removed; if the local is used only one time and there are
* no side effects to the expression on the right hand side between usage
* and initialization, the usage is replaced by the right hand side.
*/
public class MarkInlineExpression {
/**
* This does the transformation.
* @param FlowBlock the flow block to transform.
* @return true if flow block was simplified.
*/
public static boolean transform(InstructionContainer ic,
StructuredBlock last) {
int params = ic.getInstruction().getOperandCount();
if (params == 0)
return false;
ComplexExpression parent = null;
Expression expr = ic.getInstruction();
if (!(last.outer instanceof SequentialBlock))
return false;
SequentialBlock sequBlock = (SequentialBlock)last.outer;
int localCount = 0;
while (sequBlock.subBlocks[0] instanceof InstructionBlock) {
InstructionBlock assign =
(InstructionBlock) sequBlock.subBlocks[0];
if (!(assign.getInstruction().getOperator()
instanceof LocalStoreOperator)
|| assign.getInstruction().getOperandCount() == 0)
break;
LocalStoreOperator store = (LocalStoreOperator)
assign.getInstruction().getOperator();
if (!store.getLocal().onlyUsedInside(expr))
break;
localCount++;
if (!(sequBlock.outer instanceof SequentialBlock))
break;
sequBlock = (SequentialBlock)sequBlock.outer;
}
if (localCount == 0)
return false;
Expression[] stores = new Expression[localCount];
sequBlock = (SequentialBlock) last.outer;
for (int i=0; i<stores; i++) {
stores[i] = ((InstructionBlock)sequBlock.subBlocks[0])
.getInstruction();
LocalStoreOperator store =
(LocalStoreOperator) stores[i].getOperator();
if (!store.getLocal().onlyUsedInside(expr))
stores[i].get.markInlinedIn(expr);
sequBlock = (SequentialBlock)sequBlock.outer;
}
expr.markInlineExpression(stores);
ic.moveDefinitions(sequBlock, last);
last.replace(sequBlock);
return true;
}
}