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account for control dependences of phi nodes 

git-svn-id: https://wala.svn.sourceforge.net/svnroot/wala/trunk@2967 f5eafffb-2e1d-0410-98e4-8ec43c5233c4
This commit is contained in:
dolby-oss 2008-07-27 21:37:47 +00:00
parent 8c19ca57b0
commit 86a007ea0d
1 changed files with 52 additions and 17 deletions
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69
com.ibm.wala.core/src/com/ibm/wala/ipa/slicer/PDG.java
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@ -35,23 +35,7 @@ import com.ibm.wala.ipa.slicer.Slicer.ControlDependenceOptions;
import com.ibm.wala.ipa.slicer.Slicer.DataDependenceOptions;
import com.ibm.wala.ipa.slicer.Statement.Kind;
import com.ibm.wala.shrikeBT.IInstruction;
import com.ibm.wala.ssa.DefUse;
import com.ibm.wala.ssa.IR;
import com.ibm.wala.ssa.ISSABasicBlock;
import com.ibm.wala.ssa.SSAAbstractInvokeInstruction;
import com.ibm.wala.ssa.SSAAbstractThrowInstruction;
import com.ibm.wala.ssa.SSAArrayLengthInstruction;
import com.ibm.wala.ssa.SSAArrayReferenceInstruction;
import com.ibm.wala.ssa.SSACFG;
import com.ibm.wala.ssa.SSACheckCastInstruction;
import com.ibm.wala.ssa.SSAFieldAccessInstruction;
import com.ibm.wala.ssa.SSAGetCaughtExceptionInstruction;
import com.ibm.wala.ssa.SSAInstanceofInstruction;
import com.ibm.wala.ssa.SSAInstruction;
import com.ibm.wala.ssa.SSANewInstruction;
import com.ibm.wala.ssa.SSAPhiInstruction;
import com.ibm.wala.ssa.SSAPiInstruction;
import com.ibm.wala.ssa.SSAReturnInstruction;
import com.ibm.wala.ssa.*;
import com.ibm.wala.types.TypeReference;
import com.ibm.wala.util.collections.Filter;
import com.ibm.wala.util.collections.FilterIterator;
@ -303,6 +287,57 @@ public class PDG implements NumberedGraph<Statement> {
// for (int i = 0; i < paramCalleeStatements.length; i++) {
// addEdge(methodEntry, paramCalleeStatements[i]);
// }
/**
* JTD: While phi nodes live in a particular basic block, they
* represent a meet of values from multiple blocks. Hence, they
* are really like multiple statements that are control dependent
* in the manner of the predecessor blocks. When the slicer is
* following both data and control dependences, it therefore seems
* right to add control dependence edges to represent how a phi
* node depends on predecessor blocks.
*/
if (dOptions.equals(DataDependenceOptions.FULL)) {
for (ISSABasicBlock bb : cdg) {
for(Iterator<SSAPhiInstruction> ps = bb.iteratePhis();
ps.hasNext(); )
{
SSAPhiInstruction phi = ps.next();
Statement phiSt =
ssaInstruction2Statement(phi, ir, instructionIndices);
for (Iterator<? extends ISSABasicBlock> preds = controlFlowGraph.getPredNodes(bb);
preds.hasNext();)
{
ISSABasicBlock pb = preds.next();
if (controlFlowGraph.getSuccNodeCount(pb) > 1) {
// in this case, there is more than one edge from the
// predecessor block, hence the phi node actually
// depends on the last instruction in the previous
// block, rather than having the same dependences as
// statements in that block.
SSAInstruction pss =
ir.getInstructions()[pb.getLastInstructionIndex()];
assert pss != null;
Statement pst =
ssaInstruction2Statement(pss, ir, instructionIndices);
delegate.addEdge(pst, phiSt);
} else {
for (Iterator<? extends ISSABasicBlock> cdps = cdg.getPredNodes(pb);
cdps.hasNext();)
{
ISSABasicBlock cpb = cdps.next();
SSAInstruction cps =
ir.getInstructions()[cpb.getLastInstructionIndex()];
assert cps != null;
Statement cpst =
ssaInstruction2Statement(cps, ir, instructionIndices);
delegate.addEdge(cpst, phiSt);
}
}
}
}
}
}
}
/**