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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [SIMD] shuffle even/odd, extend, add should generate extadd_pairwise"
href="https://bugs.llvm.org/show_bug.cgi?id=50808">50808</a>
</td>
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<tr>
<th>Summary</th>
<td>[SIMD] shuffle even/odd, extend, add should generate extadd_pairwise
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: WebAssembly
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>clang@evan.coeusgroup.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>With -msimd128, shuffling to extract even and odd elements, then extending
those and adding the result should result in one of the extadd_pairwise
instructions (assuming 8 or 16 bit inputs). It doesn't.
Right now they result in some rather atrocious code, but I filed that as
#50807. This issue is about generating an extadd_pairwise instruction.
Example (Compiler Explorer: <a href="https://godbolt.org/z/94n6sooTs">https://godbolt.org/z/94n6sooTs</a>):
#include <stdint.h>
#pragma clang diagnostic ignored "-Wmissing-prototypes"
typedef int8_t i8x16 __attribute__((__vector_size__(16)));
typedef int16_t i16x8 __attribute__((__vector_size__(16)));
typedef int32_t i32x4 __attribute__((__vector_size__(16)));
typedef uint8_t u8x16 __attribute__((__vector_size__(16)));
typedef uint16_t u16x8 __attribute__((__vector_size__(16)));
typedef uint32_t u32x4 __attribute__((__vector_size__(16)));
i16x8
i8x16_extadd_pairwise(i8x16 a) {
return (i16x8) {
__builtin_convertvector(__builtin_shufflevector(a, a, 0, 2, 4, 6, 8, 10,
12, 14), i16x8) +
__builtin_convertvector(__builtin_shufflevector(a, a, 1, 3, 5, 7, 9, 11,
13, 15), i16x8)
};
}
i32x4
i16x8_extadd_pairwise(i16x8 a) {
return (i32x4) {
__builtin_convertvector(__builtin_shufflevector(a, a, 0, 2, 4, 6), i32x4)
+
__builtin_convertvector(__builtin_shufflevector(a, a, 1, 3, 5, 7), i32x4)
};
}
u16x8
u8x16_extadd_pairwise(i8x16 a) {
return (u16x8) {
__builtin_convertvector(__builtin_shufflevector(a, a, 0, 2, 4, 6, 8, 10,
12, 14), u16x8) +
__builtin_convertvector(__builtin_shufflevector(a, a, 1, 3, 5, 7, 9, 11,
13, 15), u16x8)
};
}
u32x4
u16x8_extadd_pairwise(i16x8 a) {
return (u32x4) {
__builtin_convertvector(__builtin_shufflevector(a, a, 0, 2, 4, 6), u32x4)
+
__builtin_convertvector(__builtin_shufflevector(a, a, 1, 3, 5, 7), u32x4)
};
}</pre>
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