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handle the table switch operation

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Volker Berlin 2018-05-05 21:43:30 +02:00
parent 7f92d062e9
commit 8ed4a37413
1 changed files with 73 additions and 1 deletions
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74
src/de/inetsoftware/jwebassembly/module/BranchManger.java
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@ -209,6 +209,78 @@ class BranchManger {
* the not consumed operations in the parent branch
*/
private void caculateSwitch( BranchNode parent, SwitchParsedBlock switchBlock, List<ParsedBlock> parsedOperations ) {
int startPosition = switchBlock.startPosition;
int posCount = switchBlock.positions.length;
boolean isTable = switchBlock.keys.length == 1;
if( isTable ) {
SwitchCase[] cases = new SwitchCase[posCount+1];
SwitchCase switchCase = cases[posCount] = new SwitchCase();
switchCase.key = Integer.MAX_VALUE;
switchCase.position = switchBlock.defaultPosition;
for( int i = 0; i < switchBlock.positions.length; i++ ) {
switchCase = cases[i] = new SwitchCase();
switchCase.key = i;
switchCase.position = switchBlock.positions[i];
}
// calculate the block number for ever switch case depending its position order
Arrays.sort( cases, (a, b) -> Integer.compare( a.position, b.position ) );
int blockCount = 0;
int lastPosition = -1;
BranchNode brTableNode = new BranchNode( startPosition, startPosition, WasmBlockOperator.BR_TABLE, null );
BranchNode blockNode = brTableNode;
for( int i = 0; i < cases.length; i++ ) {
switchCase = cases[i];
switchCase.block = blockCount;
int currentPosition = switchCase.position;
if( lastPosition != currentPosition ) {
lastPosition = currentPosition;
blockCount++;
BranchNode node = new BranchNode( startPosition, startPosition + currentPosition, WasmBlockOperator.BLOCK, WasmBlockOperator.END );
node.add( blockNode );
blockNode = node;
}
}
// handle the GOTO at the end of the CASE blocks.
int endPosition = startPosition + lastPosition;
for( int i = 0; i < parsedOperations.size(); i++ ) {
ParsedBlock parsedBlock = parsedOperations.get( i );
if( parsedBlock.startPosition < endPosition ) {
if( parsedBlock.endPosition >= endPosition && parsedBlock.op == JavaBlockOperator.GOTO ) {
parsedOperations.remove( i );
endPosition = parsedBlock.endPosition;
}
} else {
break;
}
}
// Create the main block around the switch
BranchNode switchNode = new BranchNode( startPosition, endPosition, WasmBlockOperator.BLOCK, WasmBlockOperator.END );
switchNode.add( blockNode );
parent.add( switchNode );
// sort back in the natural order and create a br_table
Arrays.sort( cases, (a, b) -> Integer.compare( a.key, b.key ) );
int[] data = new int[cases.length];
for( int i = 0; i < data.length; i++ ) {
data[i] = cases[i].block;
}
brTableNode.data = data;
} else {
throw new WasmException( "Unsupported switch with lookup", null, ((ParsedBlock)switchBlock).lineNumber );
}
}
/**
* Helper structure for caculateSwitch
*/
private static class SwitchCase {
int key;
int position;
int block;
}
/**
@ -276,7 +348,7 @@ class BranchManger {
private final WasmBlockOperator endOp;
private final Object data;
private Object data;
/**
* Create a new description.