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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Compiler no longer producing hsub instruction after upstream commit be69e66b1cd8"
href="https://bugs.llvm.org/show_bug.cgi?id=48823">48823</a>
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<th>Summary</th>
<td>Compiler no longer producing hsub instruction after upstream commit be69e66b1cd8
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<th>Product</th>
<td>new-bugs
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>new bugs
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>douglas_yung@playstation.sony.com
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
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<p>
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<pre>After commit be69e66b1cd8, one of our internal tests is no longer generating a
horizontal subtraction instruction for the following code:
__attribute__((noinline))
__m128 sub_ps_004(__m128 a, __m128 b) {
__m128 r = (__m128){ a[0] - a[1], a[2] - a[3], b[0] - b[1], b[2] - b[3] };
return __builtin_shufflevector(r, a, 0, -1, -1, 3);
}
When compiling with a compiler targeting the PS4 (x86_64-scei-ps4), the
comipler previously generated this code for the function:
(clang -S -O2 --target=x86_64-scei-ps4)
vhsubps %xmm1, %xmm0, %xmm0
However after the change above, the compiler now generates the following code:
vshufps $229, %xmm1, %xmm0, %xmm2 # xmm2 = xmm0[1,1],xmm1[2,3]
vshufps $164, %xmm1, %xmm0, %xmm0 # xmm0 = xmm0[0,1],xmm1[2,2]
vsubps %xmm2, %xmm0, %xmm0</pre>
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