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<b><a class="bz_bug_link
bz_status_NEW "
title="NEW - Adding a single, meaningless if-else to a shader source leads to different image"
href="https://bugs.freedesktop.org/show_bug.cgi?id=100303#c4">Comment # 4</a>
on <a class="bz_bug_link
bz_status_NEW "
title="NEW - Adding a single, meaningless if-else to a shader source leads to different image"
href="https://bugs.freedesktop.org/show_bug.cgi?id=100303">bug 100303</a>
from <span class="vcard"><a class="email" href="mailto:t_arceri@yahoo.com.au" title="Timothy Arceri <t_arceri@yahoo.com.au>"> <span class="fn">Timothy Arceri</span></a>
</span></b>
<pre>(In reply to Roland Scheidegger from <a href="show_bug.cgi?id=100303#c2">comment #2</a>)
<span class="quote">>
> So, for some reason the compiler completely eliminated the conditional
> return in the loop inside the branch and figured it will just
> unconditionally return the value corresponding to not meeting that condition
> in the loop in the original code. (In fact all code in this function with
> the exception of the return statement is now effectively dead.)
> Not sure though which lowering stage did this damage...</span >
I think there is a bug in do_lower_jumps(). I noticed a similar bug when
working on loop unrolling for NIR. I wrote the following tests that pass on NIR
unrolling/return lower but fail in GLSL IR.
piglit/tests/spec/glsl-1.10/execution/vs-nested-return-sibling-loop.shader_tes
piglit/tests/spec/glsl-1.10/execution/vs-nested-return-sibling-loop2.shader_test</pre>
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