aboutsummaryrefslogtreecommitdiff
path: root/tools/js-optimizer.js
diff options
context:
space:
mode:
Diffstat (limited to 'tools/js-optimizer.js')
-rw-r--r--tools/js-optimizer.js120
1 files changed, 95 insertions, 25 deletions
diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index 32ed1cce..09791150 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -403,6 +403,23 @@ function removeUnneededLabelSettings(ast) {
// Various expression simplifications. Pre run before closure (where we still have metadata), Post run after.
function simplifyExpressionsPre(ast) {
+ // Look for (x&A)<<B>>B and replace it with X&A if possible.
+ function simplifySignExtends(ast) {
+ traverseGenerated(ast, function(node, type) {
+ if (type == 'binary' && node[1] == '>>' && node[3][0] == 'num' &&
+ node[2][0] == 'binary' && node[2][1] == '<<' && node[2][3][0] == 'num' && node[3][1] == node[2][3][1]) {
+ var innerNode = node[2][2];
+ var shifts = node[3][1];
+ if (innerNode[0] == 'binary' && innerNode[1] == '&' && innerNode[3][0] == 'num') {
+ var mask = innerNode[3][1];
+ if (mask << shifts >> shifts == mask) {
+ return innerNode;
+ }
+ }
+ }
+ });
+ }
+
// When there is a bunch of math like (((8+5)|0)+12)|0, only the external |0 is needed, one correction is enough.
// At each node, ((X|0)+Y)|0 can be transformed into (X+Y): The inner corrections are not needed
// TODO: Is the same is true for 0xff, 0xffff?
@@ -592,6 +609,7 @@ function simplifyExpressionsPre(ast) {
});
}
+ simplifySignExtends(ast);
simplifyBitops(ast);
joinAdditions(ast);
// simplifyZeroComp(ast); TODO: investigate performance
@@ -1487,7 +1505,7 @@ function registerize(ast) {
// Replace all var definitions with assignments; we will add var definitions at the top after we registerize
// We also mark local variables - i.e., having a var definition
var localVars = {};
- var hasSwitch = false; // we cannot optimize variables if there is a switch
+ var hasSwitch = false; // we cannot optimize variables if there is a switch, unless in asm mode
traverse(fun, function(node, type) {
if (type == 'var') {
node[1].forEach(function(defined) { localVars[defined[0]] = 1 });
@@ -1578,7 +1596,15 @@ function registerize(ast) {
var varLevels = {};
var possibles = {};
var unoptimizables = {};
- traverse(fun, function(node, type) {
+ function purgeLevel() {
+ // Invalidate all dominating on this level, further users make it unoptimizable
+ for (var name in levelDominations[level]) {
+ varLevels[name] = 0;
+ }
+ levelDominations[level] = null;
+ level--;
+ }
+ traverse(fun, function possibilifier(node, type) {
if (type == 'name') {
var name = node[1];
if (localVars[name]) {
@@ -1599,24 +1625,61 @@ function registerize(ast) {
}
}
} else if (type in CONTROL_FLOW) {
- level++;
- }
- }, function(node, type) {
- if (type in CONTROL_FLOW) {
- // Invalidate all dominating on this level, further users make it unoptimizable
- for (var name in levelDominations[level]) {
- varLevels[name] = 0;
+ // recurse children, in the context of a loop
+ switch(type) {
+ case 'while': case 'do': {
+ traverse(node[1], possibilifier);
+ level++;
+ traverse(node[2], possibilifier);
+ purgeLevel();
+ break;
+ }
+ case 'for': {
+ traverse(node[1], possibilifier);
+ for (var i = 2; i <= 4; i++) {
+ level++;
+ traverse(node[i], possibilifier);
+ purgeLevel();
+ }
+ break;
+ }
+ case 'if': {
+ traverse(node[1], possibilifier);
+ level++;
+ traverse(node[2], possibilifier);
+ purgeLevel();
+ if (node[3]) {
+ level++;
+ traverse(node[3], possibilifier);
+ purgeLevel();
+ }
+ break;
+ }
+ case 'switch': {
+ traverse(node[1], possibilifier);
+ var cases = node[2];
+ for (var i = 0; i < cases.length; i++) {
+ level++;
+ traverse(cases[i][1], possibilifier);
+ purgeLevel();
+ }
+ break;
+ }
+ default: throw dumpAst(node);
}
- levelDominations[level] = null;
- level--;
+ return null; // prevent recursion into children, which we already did
}
});
var optimizables = {};
- if (!hasSwitch) {
+ if (!hasSwitch || asm) {
for (var possible in possibles) {
if (!unoptimizables[possible]) optimizables[possible] = 1;
}
}
+
+ //printErr('optimizables: ' + JSON.stringify(optimizables));
+ //printErr('unoptimizables: ' + JSON.stringify(unoptimizables));
+
// Go through the function's code, assigning 'registers'.
// The only tricky bit is to keep variables locked on a register through loops,
// since they can potentially be returned to. Optimizable variables lock onto
@@ -1776,10 +1839,10 @@ function registerize(ast) {
// In memSafe mode, we are more careful and assume functions can replace HEAP and FUNCTION_TABLE, which
// can happen in ALLOW_MEMORY_GROWTH mode
-var ELIMINATION_SAFE_NODES = set('var', 'assign', 'call', 'if', 'toplevel', 'do', 'return', 'label'); // do is checked carefully, however
+var ELIMINATION_SAFE_NODES = set('var', 'assign', 'call', 'if', 'toplevel', 'do', 'return', 'label', 'switch'); // do is checked carefully, however
var NODES_WITHOUT_ELIMINATION_SIDE_EFFECTS = set('name', 'num', 'string', 'binary', 'sub', 'unary-prefix');
var IGNORABLE_ELIMINATOR_SCAN_NODES = set('num', 'toplevel', 'string', 'break', 'continue', 'dot'); // dot can only be STRING_TABLE.*
-var ABORTING_ELIMINATOR_SCAN_NODES = set('new', 'object', 'function', 'defun', 'switch', 'for', 'while', 'array', 'throw'); // we could handle some of these, TODO, but nontrivial (e.g. for while, the condition is hit multiple times after the body)
+var ABORTING_ELIMINATOR_SCAN_NODES = set('new', 'object', 'function', 'defun', 'for', 'while', 'array', 'throw'); // we could handle some of these, TODO, but nontrivial (e.g. for while, the condition is hit multiple times after the body)
function eliminate(ast, memSafe) {
// Find variables that have a single use, and if they can be eliminated, do so
@@ -1787,7 +1850,6 @@ function eliminate(ast, memSafe) {
if (asm) var asmData = normalizeAsm(func);
//printErr('eliminate in ' + func[1]);
-
// First, find the potentially eliminatable functions: that have one definition and one use
var definitions = {};
var uses = {};
@@ -1841,12 +1903,7 @@ function eliminate(ast, memSafe) {
});
// we cannot eliminate variables if there is a switch
- if (traverse(func, function(node, type) {
- if (type == 'switch') return true;
- })) {
- if (asm) denormalizeAsm(func, asmData);
- return;
- }
+ if (hasSwitch && !asm) return;
var potentials = {}; // local variables with 1 definition and 1 use
var sideEffectFree = {}; // whether a local variable has no side effects in its definition
@@ -2153,13 +2210,14 @@ function eliminate(ast, memSafe) {
invalidateCalls();
callsInvalidated = true;
}
+
allowTracking = false;
traverseInOrder(node[2]); // 2 and 3 could be 'parallel', really..
if (node[3]) traverseInOrder(node[3]);
allowTracking = true;
+
} else {
tracked = {};
- abort = true;
}
} else if (type == 'block') {
var stats = node[1];
@@ -2180,7 +2238,6 @@ function eliminate(ast, memSafe) {
traverseInOrder(node[2]);
} else {
tracked = {};
- abort = true;
}
} else if (type == 'return') {
if (node[1]) traverseInOrder(node[1]);
@@ -2188,6 +2245,17 @@ function eliminate(ast, memSafe) {
traverseInOrder(node[1]);
traverseInOrder(node[2]);
traverseInOrder(node[3]);
+ } else if (type == 'switch') {
+ traverseInOrder(node[1]);
+ var cases = node[2];
+ for (var i = 0; i < cases.length; i++) {
+ var c = cases[i];
+ assert(c[0] === null || c[0][0] == 'num' || (c[0][0] == 'unary-prefix' && c[0][2][0] == 'num'));
+ var stats = c[1];
+ for (var j = 0; j < stats.length; j++) {
+ traverseInOrder(stats[j]);
+ }
+ }
} else {
if (!(type in ABORTING_ELIMINATOR_SCAN_NODES)) {
printErr('unfamiliar eliminator scan node: ' + JSON.stringify(node));
@@ -2234,13 +2302,15 @@ function eliminate(ast, memSafe) {
}
}
traverse(func, function(block) {
- var stats = getStatements(block);
+ // Look for statements, including while-switch pattern
+ var stats = getStatements(block) || (block[0] == 'while' && block[2][0] == 'switch' ? [block[2]] : stats);
if (!stats) return;
+ //printErr('Stats: ' + JSON.stringify(stats).substr(0,100));
tracked = {};
//printErr('new StatBlock');
for (var i = 0; i < stats.length; i++) {
var node = stats[i];
- //printErr('StatBlock[' + i + '] => ' + JSON.stringify(node));
+ //printErr('StatBlock[' + i + '] => ' + JSON.stringify(node).substr(0,100));
var type = node[0];
if (type == 'stat') {
node = node[1];
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-07-24 03:11:47 +0000