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<body><span class="vcard"><a class="email" href="mailto:hans@chromium.org" title="Hans Wennborg <hans@chromium.org>"> <span class="fn">Hans Wennborg</span></a>
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<a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [x86] Tail call with conditional jumps"
href="https://bugs.llvm.org/show_bug.cgi?id=26302">bug 26302</a>
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<tr>
<th>What</th>
<th>Removed</th>
<th>Added</th>
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<td style="text-align:right;">Resolution</td>
<td>---
</td>
<td>FIXED
</td>
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<td style="text-align:right;">Status</td>
<td>REOPENED
</td>
<td>RESOLVED
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<b><a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [x86] Tail call with conditional jumps"
href="https://bugs.llvm.org/show_bug.cgi?id=26302#c7">Comment # 7</a>
on <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - [x86] Tail call with conditional jumps"
href="https://bugs.llvm.org/show_bug.cgi?id=26302">bug 26302</a>
from <span class="vcard"><a class="email" href="mailto:hans@chromium.org" title="Hans Wennborg <hans@chromium.org>"> <span class="fn">Hans Wennborg</span></a>
</span></b>
<pre>(In reply to Nikita Kniazev from <a href="show_bug.cgi?id=26302#c6">comment #6</a>)
<span class="quote">> Correct me if I am wrong. The example in the first post is not affected by
> this comment, as folding will not change the branch direction in it.</span >
But it does. Before the optimization:
testb $1, 4(%esp)
je .LBB0_2
jmp foo
.LBB0_2:
jmp bar
The "je" branches "forward" due to the code layout.
After folding:
testb $1, 4(%esp)
je bar
jmp foo
The "je" might branch "forward" or "backward" depending on where the linker
puts "bar" in relation to the current code. The code layout done by the
compiler is lost.
At least that was the motivation for restricting this to optsize.
If you want to make the case that this optimization should fire also without
optsize, please open another bug.</pre>
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