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Fix Safari dormant overhead in Live Debugger instrumentation #438

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Fix Safari dormant overhead in Live Debugger instrumentation #438

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86 changes: 38 additions & 48 deletions packages/plugins/live-debugger/EXAMPLES.md
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -7,8 +7,8 @@ plugin's [How it works](./README.md#how-it-works) section.
A few conventions used throughout:

- The injected globals (`$dd_probes`, `$dd_entry`, `$dd_return`, `$dd_throw`) are provided by the Browser Debugger SDK at runtime — see [Runtime requirements](./README.md#runtime-requirements).
- The per-function local helpers carry a numeric suffix (`$dd_p0`, `$dd_e0`, `$dd_rv0`); the index increments for each instrumented function in a file.
- The `$dd_e<N>` parameter-capture helper is only emitted when the function has parameters.
- The per-function locals carry a numeric suffix (`$dd_p0`, `$dd_rv0`); the index increments for each instrumented function in a file.
- The captured-arguments object literal (e.g. `{a, b}`) is inlined directly at each probe-guarded call site and is only emitted when the function has parameters. It is built lazily — inside the `if (probe)` / `probe ? ` guards — so dormant calls allocate nothing.
- Indentation below is reformatted for readability; the real output preserves the original source layout.

## Table of content <!-- #omit in toc -->
Expand Down Expand Up @@ -48,13 +48,12 @@ function add(a, b) {
// After
function add(a, b) {
const $dd_p0 = $dd_probes('src/utils.js;add');
const $dd_e0 = () => ({a, b});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {a, b});
const sum = a + b;
return ($dd_rv0 = sum, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), {sum}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
return ($dd_rv0 = sum, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {a, b}, {sum}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {a, b}); throw e; }
}
```

Expand All @@ -70,13 +69,12 @@ const double = (x) => x * 2;
// After
const double = (x) => {
const $dd_p0 = $dd_probes('src/utils.js;double');
const $dd_e0 = () => ({x});
try {
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {x});
const $dd_rv0 = x * 2;
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0());
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, {x});
return $dd_rv0;
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
};
```

Expand All @@ -92,20 +90,19 @@ const getObj = (x) => ({key: x});
// After
const getObj = (x) => {
const $dd_p0 = $dd_probes('src/utils.js;getObj');
const $dd_e0 = () => ({x});
try {
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {x});
const $dd_rv0 = {key: x};
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0());
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, {x});
return $dd_rv0;
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
};
```

## Function with no parameters

With no parameters, no `$dd_e0` helper is generated and the receiver (`this`) is passed without
an arguments object.
With no parameters, no arguments object is generated and the receiver (`this`) is passed without
one.

```js
// Before
Expand Down Expand Up @@ -162,13 +159,12 @@ function log(msg) {
// After
function log(msg) {
const $dd_p0 = $dd_probes('src/utils.js;log');
const $dd_e0 = () => ({msg});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {msg});
console.log(msg);
if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0());
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
if ($dd_p0) $dd_return($dd_p0, undefined, this, {msg});
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {msg}); throw e; }
}
```

Expand All @@ -189,17 +185,16 @@ function earlyExit(x) {
// After
function earlyExit(x) {
const $dd_p0 = $dd_probes('src/utils.js;earlyExit');
const $dd_e0 = () => ({x});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {x});
if (!x) {
if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0());
if ($dd_p0) $dd_return($dd_p0, undefined, this, {x});
return;
}
console.log(x);
if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0());
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
if ($dd_p0) $dd_return($dd_p0, undefined, this, {x});
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
}
```

Expand All @@ -219,15 +214,14 @@ function abs(x) {
// After
function abs(x) {
const $dd_p0 = $dd_probes('src/utils.js;abs');
const $dd_e0 = () => ({x});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {x});
if (x < 0) {
return ($dd_rv0 = -x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
return ($dd_rv0 = -x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {x}) : $dd_rv0);
}
return ($dd_rv0 = x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
return ($dd_rv0 = x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {x}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
}
```

Expand All @@ -248,16 +242,15 @@ function sign(x) {
// After
function sign(x) {
const $dd_p0 = $dd_probes('src/utils.js;sign');
const $dd_e0 = () => ({x});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {x});
if (x > 0) {
return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {x}) : $dd_rv0);
} else {
return ($dd_rv0 = -1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
return ($dd_rv0 = -1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {x}) : $dd_rv0);
}
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
}
```

Expand All @@ -280,16 +273,15 @@ function f(flag) {
// After
function f(flag) {
const $dd_p0 = $dd_probes('src/utils.js;f');
const $dd_e0 = () => ({flag});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {flag});
if (flag) {
return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {flag}) : $dd_rv0);
}
const later = 2;
return ($dd_rv0 = later, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), {later}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
return ($dd_rv0 = later, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {flag}, {later}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {flag}); throw e; }
}
```

Expand Down Expand Up @@ -355,13 +347,12 @@ class Widget extends Base {
let $dd_t;
($dd_t = super(items.map((x) => {
const $dd_p0 = $dd_probes('src/widget.js;<anonymous>@4:16:0');
const $dd_e0 = () => ({x});
try {
if ($dd_p0) $dd_entry($dd_p0, $dd_t, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, $dd_t, {x});
const $dd_rv0 = x * 2;
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, $dd_t, $dd_e0());
if ($dd_p0) $dd_return($dd_p0, $dd_rv0, $dd_t, {x});
return $dd_rv0;
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, $dd_t, $dd_e0()); throw e; }
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, $dd_t, {x}); throw e; }
})));
}
}
Expand Down Expand Up @@ -419,12 +410,11 @@ class Widget extends Base {
constructor(items) {
const double = function(x) {
const $dd_p0 = $dd_probes('src/widget.js;double');
const $dd_e0 = () => ({x});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
return ($dd_rv0 = x * 2, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
if ($dd_p0) $dd_entry($dd_p0, this, {x});
return ($dd_rv0 = x * 2, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {x}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {x}); throw e; }
};
super(items.map(double));
}
Expand Down
7 changes: 3 additions & 4 deletions packages/plugins/live-debugger/README.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -89,13 +89,12 @@ function add(a, b) {
// After
function add(a, b) {
const $dd_p0 = $dd_probes('src/utils.js;add');
const $dd_e0 = () => ({a, b});
try {
let $dd_rv0;
if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());
if ($dd_p0) $dd_entry($dd_p0, this, {a, b});
const sum = a + b;
return ($dd_rv0 = sum, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), {sum}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }
return ($dd_rv0 = sum, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, {a, b}, {sum}) : $dd_rv0);
} catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, {a, b}); throw e; }
}
```

Expand Down
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