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<body><span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span> changed
<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [LoopUnroll] compile-time explosion with assumes at -O3"
href="https://bugs.llvm.org/show_bug.cgi?id=49171">bug 49171</a>
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<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>CONFIRMED
</td>
<td>RESOLVED
</td>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [LoopUnroll] compile-time explosion with assumes at -O3"
href="https://bugs.llvm.org/show_bug.cgi?id=49171#c9">Comment # 9</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [LoopUnroll] compile-time explosion with assumes at -O3"
href="https://bugs.llvm.org/show_bug.cgi?id=49171">bug 49171</a>
from <span class="vcard"><a class="email" href="mailto:spatel+llvm@rotateright.com" title="Sanjay Patel <spatel+llvm@rotateright.com>"> <span class="fn">Sanjay Patel</span></a>
</span></b>
<pre>(In reply to Nikita Popov from <a href="show_bug.cgi?id=49171#c8">comment #8</a>)
<span class="quote">> @spatel Your patch with a limit of 15 looks fine to me. I don't think we
> need to do further experiments, as this is a question of worst-case
> complexity rather than average-case performance.</span >
Thanks! Committed the quick fix here - <a href="https://reviews.llvm.org/rG378941f611ab">https://reviews.llvm.org/rG378941f611ab</a>
I think that's enough to say this bug is fixed, but reopen if I got that wrong.
I haven't been following the details of guaranteed progress discussions, so not
sure how to test this...does this correctly implement the suggested check for
function attributes?
diff --git a/llvm/lib/Analysis/ValueTracking.cpp
b/llvm/lib/Analysis/ValueTracking.cpp
index 493eb08bb9b0..ef78847cb43e 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -548,6 +548,12 @@ bool llvm::isValidAssumeForContext(const Instruction *Inv,
if (Inv == CxtI)
return false;
+ // Use function attributes to check if execution must reach the assume.
+ const Function *F = CxtI->getFunction();
+ if (F->hasFnAttribute(Attribute::WillReturn) ||
+ F->hasFnAttribute(Attribute::NoUnwind))
+ return !isEphemeralValueOf(Inv, CxtI);
+
// The context comes first, but they're both in the same block.
// Make sure there is nothing in between that might interrupt
// the control flow, not even CxtI itself.</pre>
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