refactor vacuum out in js optimizer
This commit is contained in:
Alon Zakai
Родитель
8f69b282df
Коммит
aa9985f119
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@ -357,6 +357,77 @@ function simplifyExpressionsPost(ast) {
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simplifyNotComps(ast);
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}
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// Clear out empty ifs and blocks, and redundant blocks/stats and so forth
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function vacuum(ast) {
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var ret;
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var more = true;
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while (more) {
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more = false;
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ast[1].forEach(function(node, i) {
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function simplifyList(node, i) {
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var changed = false;
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var pre = node[i].length;
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node[i] = node[i].filter(function(blockItem) { return !jsonCompare(blockItem, emptyNode()) });
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if (node[i].length < pre) changed = true;
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// Also, seek blocks with single items we can simplify
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node[i] = node[i].map(function(subNode) {
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if (subNode[0] == 'block' && typeof subNode[1] == 'object' && subNode[1].length == 1 && subNode[1][0][0] == 'if') {
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return subNode[1][0];
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}
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return subNode;
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});
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if (changed) {
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more = true;
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return node;
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}
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}
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var type = node[0];
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if (type == 'defun' && isGenerated(node[1])) {
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traverse(node, function(node, type) {
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if (type == 'if' && node[2][0] == 'block' && (!node[2][1] || node[2][1].length == 0)) {
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more = true;
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if (node[2][2]) { // if there is an else, return that
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return node[2][2];
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} else {
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return emptyNode();
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}
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} else if (type == 'block' && !node[1]) {
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return emptyNode();
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} else if (type == 'block' && (node[1].length == 0 || (node[1].length == 1 && jsonCompare(node[1][0], emptyNode())))) {
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more = true;
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return emptyNode();
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} else if (type == 'block' && node[1].length == 1 && node[1][0][0] == 'block') {
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more = true;
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return node[1][0];
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} else if (type == 'stat' && node[1][0] == 'block') {
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more = true;
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return node[1];
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} else if (type == 'block' && typeof node[1] == 'object') {
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ret = simplifyList(node, 1);
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if (ret) return ret;
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} else if (type == 'defun' && node[3].length == 1 && node[3][0][0] == 'block') {
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more = true;
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node[3] = node[3][0][1];
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return node;
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} else if (type == 'defun') {
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ret = simplifyList(node, 3);
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if (ret) return ret;
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} else if (type == 'do' && node[1][0] == 'num' && jsonCompare(node[2], emptyNode())) {
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more = true;
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return emptyNode();
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} else if (type == 'label' && jsonCompare(node[2], emptyNode())) {
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more = true;
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return emptyNode();
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} else if (type == 'if' && jsonCompare(node[3], emptyNode())) { // empty else clauses
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node[3] = null;
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return node;
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}
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});
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}
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});
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}
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}
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// Multiple blocks from the relooper are, in general, implemented by
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// if (__label__ == x) { } else if ..
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// and branching into them by
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@ -429,74 +500,7 @@ function hoistMultiples(ast) {
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}
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});
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// Clear out empty ifs and blocks, and redundant blocks/stats
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var ret;
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var more = true;
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while (more) {
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more = false;
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ast[1].forEach(function(node, i) {
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function simplifyList(node, i) {
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var changed = false;
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var pre = node[i].length;
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node[i] = node[i].filter(function(blockItem) { return !jsonCompare(blockItem, emptyNode()) });
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if (node[i].length < pre) changed = true;
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// Also, seek blocks with single items we can simplify
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node[i] = node[i].map(function(subNode) {
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if (subNode[0] == 'block' && typeof subNode[1] == 'object' && subNode[1].length == 1 && subNode[1][0][0] == 'if') {
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return subNode[1][0];
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}
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return subNode;
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});
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if (changed) {
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more = true;
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return node;
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}
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}
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var type = node[0];
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if (type == 'defun' && isGenerated(node[1])) {
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traverse(node, function(node, type) {
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if (type == 'if' && node[2][0] == 'block' && (!node[2][1] || node[2][1].length == 0)) {
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more = true;
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if (node[2][2]) { // if there is an else, return that
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return node[2][2];
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} else {
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return emptyNode();
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}
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} else if (type == 'block' && !node[1]) {
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return emptyNode();
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} else if (type == 'block' && (node[1].length == 0 || (node[1].length == 1 && jsonCompare(node[1][0], emptyNode())))) {
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more = true;
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return emptyNode();
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} else if (type == 'block' && node[1].length == 1 && node[1][0][0] == 'block') {
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more = true;
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return node[1][0];
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} else if (type == 'stat' && node[1][0] == 'block') {
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more = true;
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return node[1];
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} else if (type == 'block' && typeof node[1] == 'object') {
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ret = simplifyList(node, 1);
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if (ret) return ret;
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} else if (type == 'defun' && node[3].length == 1 && node[3][0][0] == 'block') {
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more = true;
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node[3] = node[3][0][1];
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return node;
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} else if (type == 'defun') {
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ret = simplifyList(node, 3);
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if (ret) return ret;
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} else if (type == 'do' && node[1][0] == 'num' && jsonCompare(node[2], emptyNode())) {
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more = true;
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return emptyNode();
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} else if (type == 'label' && jsonCompare(node[2], emptyNode())) {
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more = true;
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return emptyNode();
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} else if (type == 'if' && jsonCompare(node[3], emptyNode())) { // empty else clauses
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node[3] = null;
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return node;
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}
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});
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}
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});
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}
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vacuum(ast);
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}
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// Simplifies loops
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@ -576,6 +580,8 @@ function loopOptimizer(ast) {
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// TODO: pass 1: Removal of unneeded continues, breaks if they get us to where we are already going. That will
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// help the next pass.
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passTwo(ast);
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vacuum(ast);
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}
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// Passes table
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