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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] pmin / pmax patterns not recognized"
href="https://bugs.llvm.org/show_bug.cgi?id=50793">50793</a>
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<th>Summary</th>
<td>[SIMD] pmin / pmax patterns not recognized
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: WebAssembly
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>clang@evan.coeusgroup.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>The compiler doesn't seem to recognize the obvious pattern for pmin and pmax,
and generates a comparison and a bitselect instead of pmin or pmax. Quick
example below (or Compiler Explorer at <a href="https://godbolt.org/z/Y6K6KssT3">https://godbolt.org/z/Y6K6KssT3</a>)
#include <wasm_simd128.h>
typedef float f32x4 __attribute__((__vector_size__(16)));
typedef int32_t i32x4 __attribute__((__vector_size__(16)));
typedef double f64x2 __attribute__((__vector_size__(16)));
typedef int64_t i64x2 __attribute__((__vector_size__(16)));
f32x4
pmin32(f32x4 a, f32x4 b) {
i32x4 mask = (b < a);
return (f32x4) (
(((i32x4) b) & mask) |
(((i32x4) a) & ~mask));
}
f32x4
pmax32(f32x4 a, f32x4 b) {
i32x4 mask = (a < b);
return (f32x4) (
(((i32x4) b) & mask) |
(((i32x4) a) & ~mask));
}
f64x2
pmin64(f64x2 a, f64x2 b) {
i64x2 mask = (b < a);
return (f64x2) (
(((i64x2) b) & mask) |
(((i64x2) a) & ~mask));
}
f64x2
pmax64(f64x2 a, f64x2 b) {
i64x2 mask = (a < b);
return (f64x2) (
(((i64x2) b) & mask) |
(((i64x2) a) & ~mask));
}</pre>
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