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Improve the loop compiling and add support for while{} loops with condition on loop start.

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This commit is contained in:
Volker 2018-08-02 12:18:31 +02:00
parent 9c1215720d
commit f2942bffc5
1 changed files with 85 additions and 5 deletions
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90
src/de/inetsoftware/jwebassembly/module/BranchManger.java
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@ -110,7 +110,8 @@ class BranchManger {
* virtual loop operator on the target position of GOTO operators with a negative offset.
*/
private void addLoops() {
for( ParsedBlock parsedBlock : allParsedOperations ) {
for( int b = 0; b < allParsedOperations.size(); b++ ) {
ParsedBlock parsedBlock = allParsedOperations.get( b );
if( parsedBlock.startPosition > parsedBlock.endPosition ) {
switch ( parsedBlock.op ) {
case GOTO: // do while(true) loop; Continue
@ -126,6 +127,57 @@ class BranchManger {
default:
throw new WasmException( "Unimplemented loop code operation: " + parsedBlock.op, null, parsedBlock.lineNumber );
}
} else {
switch ( parsedBlock.op ) {
case GOTO:
// forward GOTO can be a while(condition) loop.
// while(condition) {
// ....
// }
// will be compiled from Java to:
// GOTO CONDITION:
// START:
// ....
// CONDITION:
// if<cond> START:
// we can not match this in WASM because a missing GOTO that we need to move the condition to the start of the loop
int nextPos = parsedBlock.startPosition + 3;
for( int n = b + 1; n < allParsedOperations.size(); n++ ) {
ParsedBlock nextBlock = allParsedOperations.get( n );
if( nextBlock.op == JavaBlockOperator.IF && nextBlock.endPosition == nextPos ) {
int conditionStart = parsedBlock.endPosition; // 15
int conditionEnd = nextBlock.startPosition + 3; // 22
int conditionNew = parsedBlock.startPosition; // 4
int conditionIdx = -1;
int i;
for( i = 0; i < instructions.size(); i++ ) {
WasmInstruction instr = instructions.get( i );
int codePos = instr.getCodePosition();
if( codePos == nextPos ) {
conditionIdx = i;
}
if( codePos >= conditionEnd ) {
break;
}
if( codePos >= conditionStart ) {
instr.setCodePosition( conditionNew );
instructions.remove( i );
instructions.add( conditionIdx++, instr );
}
}
parsedBlock.op = JavaBlockOperator.LOOP;
parsedBlock.endPosition = conditionEnd;
allParsedOperations.remove( n );
instructions.add( i, new WasmBlockInstruction( WasmBlockOperator.BR, 0, conditionNew ) );
instructions.add( conditionIdx++, new WasmBlockInstruction( WasmBlockOperator.BR_IF, 1, conditionNew ) );
break;
}
}
break;
default:
}
}
}
@ -191,8 +243,16 @@ class BranchManger {
calculate( branch, parsedOperations.subList( 0, i ) );
}
endPos = parsedBlock.endPosition;
branch = new BranchNode( startBlock.endPosition, endPos, WasmBlockOperator.ELSE, WasmBlockOperator.END );
parent.add( branch );
int breakDeep = calculateBreakDeep( parent, endPos );
if( breakDeep >= 0 ) {
branch.endOp = WasmBlockOperator.END;
branch.add( new BranchNode( startBlock.endPosition, endPos, WasmBlockOperator.BR, null, breakDeep + 1 ) );
endPos = branch.endPos;
} else {
branch = new BranchNode( startBlock.endPosition, endPos, WasmBlockOperator.ELSE, WasmBlockOperator.END );
parent.add( branch );
}
break;
}
if( parsedBlock.startPosition > gotoPos ) {
@ -219,6 +279,24 @@ class BranchManger {
}
}
/**
* Calculate the deep of a break.
*
* @param parent
* the current parent node.
* @param endPos
* the end position of the jump
* @return the deep level for "br" or -1 if there is no parent node with this end position
*/
private int calculateBreakDeep( BranchNode parent, int endPos ) {
int deep = -1;
while( parent != null && parent.endPos == endPos ) {
deep++;
parent = parent.parent;
}
return deep;
}
/**
* Calculate the blocks of a switch.
*
@ -418,8 +496,10 @@ class BranchManger {
* the not consumed operations in the parent branch
*/
private void caculateLoop ( BranchNode parent, ParsedBlock loopBlock, List<ParsedBlock> parsedOperations ) {
BranchNode blockNode = new BranchNode( loopBlock.startPosition, loopBlock.endPosition, WasmBlockOperator.BLOCK, WasmBlockOperator.END );
parent.add( blockNode );
BranchNode loopNode = new BranchNode( loopBlock.startPosition, loopBlock.endPosition, WasmBlockOperator.LOOP, WasmBlockOperator.END );
parent.add( loopNode );
blockNode.add( loopNode );
int idx = 0;
for( ; idx < parsedOperations.size(); idx++ ) {
@ -502,7 +582,7 @@ class BranchManger {
private final WasmBlockOperator startOp;
private final WasmBlockOperator endOp;
private WasmBlockOperator endOp;
private Object data;