<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css" style="display:none;"> P {margin-top:0;margin-bottom:0;} </style>
</head>
<body dir="ltr">
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
> when you say "more variables being emitted to DWARF with 0% coverage" - what do you mean by that? Are we counting a variable with no location attribute as being 100% covered, because it isn't partially covered? Could we instead count such variables as 0%
covered?</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
Not exactly, it's that we aren't considering them at all. If we have 2 variables <code>
a</code> and <code>b</code> with 100% and 50% coverage respectively, we'd have 75% total coverage (assuming they both occupy identically sized scopes). If a new optimization causes us to drop
<code>b</code>'s coverage to 0%, then we would expect the overall coverage to drop to 50%. However, we may end up dropping
<code>b</code> entirely from the DWARF, in which case the <code>dwarfdump</code> statistics see that we only have 1 variable and it has 100% coverage, giving us 100% overall coverage. While it would be accurate to count these missing variables as 0% covered,
if there's no mention of them in the DWARF then there is no way for <code>dwarfdump</code> to know they exist.<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
I'm not actually sure what causes variables to be dropped from the DWARF entirely, as opposed to them existing but having an unknown location for their entire scope; however, outside of our desire to use
<code>dwarfdump</code> to analyze our debug info it's simply more efficient to omit variables with no location, since they inflate the debug info size and I don't believe there's any practical value in having them.</div>
<div style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
</body>
</html>