git-svn-id: https://svn.code.sf.net/p/jode/code/trunk@11 379699f6-c40d-0410-875b-85095c16579estable
jochen
27 years ago
parent
f3f21e7d2c
commit
3360965bb1
@ -1,23 +1,40 @@ |
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package jode; |
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public class CreateWhileStatements implements Transformation { |
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public class CreateWhileStatements extends FlowTransformation |
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implements Transformation { |
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public InstructionHeader transform(InstructionHeader gotoIH) { |
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if (gotoIH.flowType != gotoIH.GOTO || gotoIH.nextInstruction == null || |
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gotoIH.successors[0].addr < gotoIH.nextInstruction.addr) |
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if (gotoIH.flowType == gotoIH.IFGOTO && |
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gotoIH.successors[1] == gotoIH) |
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/* This is an empty while loop |
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*/ |
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return new WhileInstructionHeader(gotoIH, gotoIH); |
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if (gotoIH.flowType != gotoIH.GOTO || |
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gotoIH.nextInstruction == null || |
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gotoIH.successors[0].addr < gotoIH.nextInstruction.addr || |
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gotoIH.outer != gotoIH.successors[0].outer) |
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return null; |
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InstructionHeader block = gotoIH.nextInstruction; |
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InstructionHeader ifgoto = gotoIH.successors[0]; |
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if (ifgoto.getFlowType() != ifgoto.IFGOTO || |
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ifgoto.successors[1] != block || |
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ifgoto.outer != block.outer) |
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ifgoto.outer != ifgoto.successors[1].outer) |
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return null; |
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InstructionHeader next = UnoptimizeWhileLoops(ifgoto.successors[1]); |
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if (next != gotoIH.nextInstruction) |
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return null; |
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if (next != ifgoto.successors[1]) { |
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ifgoto.successors[1].predecessors.removeElement(ifgoto); |
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ifgoto.successors[1] = next; |
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ifgoto.successors[1].predecessors.addElement(ifgoto); |
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} |
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if(Decompiler.isVerbose) |
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System.err.print("w"); |
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return new WhileInstructionHeader(gotoIH, ifgoto, block); |
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return new WhileInstructionHeader(gotoIH, ifgoto); |
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} |
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} |
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@ -0,0 +1,79 @@ |
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package jode; |
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abstract public class FlowTransformation { |
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/** |
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* This class reverses javac's optimization of while loops. |
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* A while loop is normally implemented as follows: |
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* |
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* <pre> |
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* loop: goto cond; |
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* head: <inner block> |
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* cond: if <condition> goto head; |
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* </pre> |
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* |
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* The problem is, if a while loop is the destination of a jump |
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* (e.g. it's in the else-part of an if, but there are many more |
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* cases). Then the first goto may or may not be removed (depends |
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* on the special case) and the previous instruction jumps |
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* directly to cond. <p> |
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* |
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* If we detect an if, that jumps backwards, but in the same block |
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* we assume that it belongs to a while statement and bring it to |
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* the above standard format. <p> |
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* |
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* If this function returns with another Header, it is guaranteed |
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* that lies in the same block. |
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* |
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* @param cond The destination of a jump. |
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* @return loop, if this is an while. loop is generated on |
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* the fly if it didn't exists before. If this isn't a while at |
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* all, the parameter is returned unchanged. |
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*/ |
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public InstructionHeader UnoptimizeWhileLoops(InstructionHeader dest) { |
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if (dest.flowType != dest.IFGOTO || |
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dest.successors[1].addr >= dest.addr || |
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dest.successors[1].outer != dest.outer) |
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return dest; |
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/* Okay, initial checking done, this really looks like a while |
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* statement. Now we call us recursively, in case the first |
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* instruction of this while loop is a while loop again.<p> |
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* |
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* This won't lead to infinite recursion because the |
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* address of the instruction will always decrease. |
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*/ |
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InstructionHeader head = UnoptimizeWhileLoops(dest.successors[1]); |
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/* Now we are at head. Look in front of this if loop is |
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* already existing. If this is the case simply return it. |
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*/ |
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if (head.prevInstruction != null && |
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head.prevInstruction.flowType == head.GOTO && |
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head.prevInstruction.successors[0] == dest) |
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return head.prevInstruction; |
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/* No there was no loop label. Create a new one. |
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*/ |
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InstructionHeader[] successors = { dest }; |
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InstructionHeader loop = |
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new InstructionHeader(head.GOTO, head.addr, head.addr, |
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successors, head.outer); |
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/* Connect it in the prev/next Instruction chain. |
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*/ |
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loop.prevInstruction = head.prevInstruction; |
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if (loop.prevInstruction != null) |
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loop.prevInstruction.nextInstruction = loop; |
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loop.nextInstruction = head; |
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head.prevInstruction = loop; |
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/* Loop has no predecessors, but a successor namely dest. |
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* The calling function may change this situation. |
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*/ |
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dest.predecessors.addElement(loop); |
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return loop; |
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} |
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} |
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@ -0,0 +1,58 @@ |
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package jode; |
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import java.util.Enumeration; |
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public class CaseInstructionHeader extends InstructionHeader { |
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int label; |
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boolean isDefault; |
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public CaseInstructionHeader(int label, boolean isDefault, |
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//Type type,
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int addr, |
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InstructionHeader parent) { |
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super(CASESTATEMENT, addr, addr, |
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new InstructionHeader[1], parent); |
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this.label = label; |
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this.isDefault = isDefault; |
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} |
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public void dumpSource(TabbedPrintWriter writer) |
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throws java.io.IOException |
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{ |
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if (Decompiler.isDebugging) { |
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dumpDebugging(writer); |
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writer.tab(); |
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} |
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if (isDefault) { |
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if (nextInstruction == null && successors[0] == null) |
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return; |
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writer.println("default:"); |
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} else |
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writer.println("case "+label+":" ); |
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writer.tab(); |
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for (InstructionHeader ih = successors[0]; ih != null; |
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ih = ih.nextInstruction) |
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ih.dumpSource(writer); |
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writer.untab(); |
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} |
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/** |
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* Get the instruction header where the next instruction is. |
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*/ |
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InstructionHeader getShadow() { |
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return (successors[0] != null ? successors[0].getShadow() : |
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getEndBlock()); |
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} |
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public InstructionHeader doTransformations(Transformation[] trafo) { |
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InstructionHeader next; |
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if (successors[0] != getEndBlock()) { |
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for (InstructionHeader ih = successors[0]; ih != null; ih = next) { |
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if ((next = ih.doTransformations(trafo)) == null) |
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next = ih.getNextInstruction(); |
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} |
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} |
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return super.doTransformations(trafo); |
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} |
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} |
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