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[graphexplorer] Use an explicit stack in forest compression to prevent JS stack overflow.

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Compare Observatory's object_graph.dart.

TEST=load a large snapshot, such as from dart2js
Change-Id: Ifea2ff4c06f5103d6f1f709fa79183398df90687
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/265404
Reviewed-by: Derek Xu <derekx@google.com>
This commit is contained in:
Ryan Macnak 2022-10-25 16:15:48 +00:00
parent 2e13c36077
commit 419d6381bb
1 changed files with 42 additions and 18 deletions
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60
runtime/tools/graphexplorer/graphexplorer.js
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@ -589,6 +589,8 @@ Graph.prototype.computeDominators = function() {
const bucket = new Array(N + 1);
const parent = this.parent_;
const dom = new Uint32Array(N + 1);
const stackNode = new Uint32Array(N + 1);
const stackState = new Uint8Array(N + 1);
for (let i = Nconnected; i > 1; i--) {
let w = vertex[i];
@ -607,7 +609,7 @@ Graph.prototype.computeDominators = function() {
continue;
}
let u = this.forestEval(v);
let u = this.forestEval(v, stackNode, stackState);
if (semi[u] < semi[w]) {
semi[w] = semi[u]
}
@ -629,7 +631,7 @@ Graph.prototype.computeDominators = function() {
if (b != null) {
for (let j = 0; j < b.length; j++) {
let v = b[j];
let u = this.forestEval(v);
let u = this.forestEval(v, stackNode, stackState);
dom[v] = semi[u] < semi[v] ? u : parent[w];
}
}
@ -653,25 +655,47 @@ Graph.prototype.computeDominators = function() {
this.dom_ = dom;
};
Graph.prototype.forestCompress = function(v) {
const ancestor = this.ancestor_;
if (ancestor[ancestor[v]] != 0) {
this.forestCompress(ancestor[v]);
const semi = this.semi_;
const label = this.label_;
if (semi[label[ancestor[v]]] < semi[label[v]]) {
label[v] = label[ancestor[v]];
}
ancestor[v] = ancestor[ancestor[v]];
}
};
Graph.prototype.forestEval = function(v) {
Graph.prototype.forestEval = function(v, stackNode, stackState) {
if (this.ancestor_[v] == 0) {
return v;
} else {
this.forestCompress(v);
return this.label_[v];
const ancestor = this.ancestor_;
const semi = this.semi_;
const label = this.label_;
{
// Inlined 'compress' with an explicit stack to prevent JS stack
// overflow.
let top = 0;
stackNode[top] = v;
stackState[top] = 0;
while (top >= 0) {
let v = stackNode[top];
let state = stackState[top];
if (state == 0) {
if (ancestor[ancestor[v]] != 0) {
stackState[top] = 1;
// Recurse with ancestor[v]
top++;
stackNode[top] = ancestor[v];
stackState[top] = 0;
} else {
top--;
}
} else {
if (semi[label[ancestor[v]]] < semi[label[v]]) {
label[v] = label[ancestor[v]];
}
ancestor[v] = ancestor[ancestor[v]];
top--;
}
}
}
if (semi[label[ancestor[v]]] >= semi[label[v]]) {
return label[v];
} else {
return label[ancestor[v]];
}
}
};