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<body><span class="vcard"><a class="email" href="mailto:dblaikie@gmail.com" title="David Blaikie <dblaikie@gmail.com>"> <span class="fn">David Blaikie</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - [SimplifyCFG] Merge DebugLoc when speculatively hoisting store instruction"
href="https://bugs.llvm.org/show_bug.cgi?id=39176">bug 39176</a>
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<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Status</td>
<td>NEW
</td>
<td>RESOLVED
</td>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>INVALID
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - [SimplifyCFG] Merge DebugLoc when speculatively hoisting store instruction"
href="https://bugs.llvm.org/show_bug.cgi?id=39176#c3">Comment # 3</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED INVALID - [SimplifyCFG] Merge DebugLoc when speculatively hoisting store instruction"
href="https://bugs.llvm.org/show_bug.cgi?id=39176">bug 39176</a>
from <span class="vcard"><a class="email" href="mailto:dblaikie@gmail.com" title="David Blaikie <dblaikie@gmail.com>"> <span class="fn">David Blaikie</span></a>
</span></b>
<pre>This current behavior looks right to me.
If the speculated store kept line 3, then profiles would give the wrong
behavior (& the debugger could cause someone to conclude invalid things about
the code) - the debugger user (or profiler) could appear to reach line 3 even
though j != 10.
(eg: a sample profiler could record a sample at the time the speculated store
was executing - recording that the program was executing line 3 at the time. A
profile based optimization could then conclude that j is == 10 for that sample
- this could bias optimizations incorrectly.
As a debugger user you could appear to step to line 3 even though j is != 10 -
confusing the user)
The merge looks OK - merging the destination with the speculated code. So if
they happen to all come from the same line of source code, then it's OK-ish.
There's no confusion/invalid implication.</pre>
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