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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] code not recognized as all_true"
href="https://bugs.llvm.org/show_bug.cgi?id=50798">50798</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[SIMD] code not recognized as all_true
</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>
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<pre>LLVM doesn't recognize that it can optimize these functions to an *.all_true
instruction.. This one might be a bit too specialized; it doesn't surprise me
at all that LLVM doesn't generate an *.all_true instruction. Still, it would
be nice since the scalar version is pretty bad.
I've included an OpenMP SIMD annotation to try to help the compiler, but
obviously it would be better if it weren't required.
Here is the example, or on Compiler Explorer at <a href="https://godbolt.org/z/x3xshzYrf">https://godbolt.org/z/x3xshzYrf</a>
if you prefer:
#include <stdint.h>
#pragma clang diagnostic ignored "-Wmissing-prototypes"
/* Because of <<a class="bz_bug_link
bz_status_NEW "
title="NEW - SIMD & reduction on signed types emits sign-conversion diagnostic"
href="show_bug.cgi?id=45959">https://bugs.llvm.org/show_bug.cgi?id=45959</a>>, not
* a WASM issue. */
#pragma clang diagnostic ignored "-Wsign-conversion"
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 int64_t i64x2 __attribute__((__vector_size__(16)));
int
i8x16_all_true(i8x16 a) {
int8_t r = ~0;
#pragma omp simd reduction(&:r)
for (int i = 0 ; i < 16 ; i++) {
r &= a[i];
}
return !!r;
}
int
i8x16_all_true_intrin(i8x16 a) {
return __builtin_wasm_all_true_i8x16(a);
}
int
i16x8_all_true(i16x8 a) {
int16_t r = ~0;
#pragma omp simd reduction(&:r)
for (int i = 0 ; i < 8 ; i++) {
r &= a[i];
}
return !!r;
}
int
i16x8_all_true_intrin(i16x8 a) {
return __builtin_wasm_all_true_i16x8(a);
}
int
i32x4_all_true(i32x4 a) {
int32_t r = ~0;
#pragma omp simd reduction(&:r)
for (int i = 0 ; i < 4 ; i++) {
r &= a[i];
}
return !!r;
}
int
i32x4_all_true_intrin(i32x4 a) {
return __builtin_wasm_all_true_i32x4(a);
}
int
i64x2_all_true(i64x2 a) {
int64_t r = ~0;
#pragma omp simd reduction(&:r)
for (int i = 0 ; i < 2 ; i++) {
r &= a[i];
}
return !!r;
}
int
i64x2_all_true_intrin(i64x2 a) {
return __builtin_wasm_all_true_i64x2(a);
}</pre>
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