<html>
<head>
<base href="https://bugs.llvm.org/">
</head>
<body><span class="vcard"><a class="email" href="mailto:lebedev.ri@gmail.com" title="Roman Lebedev <lebedev.ri@gmail.com>"> <span class="fn">Roman Lebedev</span></a>
</span> changed
<a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - InstCombine: shift amount reassociation when doing bit test"
href="https://bugs.llvm.org/show_bug.cgi?id=42399">bug 42399</a>
<br>
<table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
</tr>
<tr>
<td style="text-align:right;">Resolution</td>
<td>FIXED
</td>
<td>---
</td>
</tr>
<tr>
<td style="text-align:right;">Status</td>
<td>RESOLVED
</td>
<td>REOPENED
</td>
</tr></table>
<p>
<div>
<b><a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - InstCombine: shift amount reassociation when doing bit test"
href="https://bugs.llvm.org/show_bug.cgi?id=42399#c5">Comment # 5</a>
on <a class="bz_bug_link
bz_status_REOPENED "
title="REOPENED - InstCombine: shift amount reassociation when doing bit test"
href="https://bugs.llvm.org/show_bug.cgi?id=42399">bug 42399</a>
from <span class="vcard"><a class="email" href="mailto:lebedev.ri@gmail.com" title="Roman Lebedev <lebedev.ri@gmail.com>"> <span class="fn">Roman Lebedev</span></a>
</span></b>
<pre>... and it wasn't enough.
; Function Attrs: norecurse nounwind readnone
define i1 @test(i64 %storage, i32 %nbits) local_unnamed_addr #0 {
bb:
%skipnbits = sub nsw i32 64, %nbits
%skipnbitswide = zext i32 %skipnbits to i64
%datawide = lshr i64 %storage, %skipnbitswide
%data = trunc i64 %datawide to i32
%nbitsminusone = add nsw i32 %nbits, -1
%bitmask = shl i32 1, %nbitsminusone
%bitmasked = and i32 %bitmask, %data
%isbitunset = icmp eq i32 %bitmasked, 0
ret i1 %isbitunset
}
attributes #0 = { norecurse nounwind readnone }
Name: PR42399
%skipnbits = sub nsw i32 64, %nbits
%skipnbitswide = zext i32 %skipnbits to i64
%datawide = lshr i64 %storage, %skipnbitswide
%data = trunc i64 %datawide to i32
%nbitsminusone = add nsw i32 %nbits, -1
%bitmask = shl i32 1, %nbitsminusone
%bitmasked = and i32 %bitmask, %data
%isbitunset = icmp eq i32 %bitmasked, 0
=>
%isbitunset = icmp sgt i64 %storage, -1
<a href="https://rise4fun.com/Alive/hUu">https://rise4fun.com/Alive/hUu</a></pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>