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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - _mulx_u64() intrinsic does not generate MULX"
href="https://bugs.llvm.org/show_bug.cgi?id=45518">45518</a>
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<th>Summary</th>
<td>_mulx_u64() intrinsic does not generate MULX
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<th>Product</th>
<td>libraries
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<th>Version</th>
<td>trunk
</td>
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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
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>atdt@google.com
</td>
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<p>
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<pre>The _mulx_u64() intrinsic generates a MUL instead of a MULX:
#include <cstdint>
#include <x86intrin.h>
auto mulx(uint64_t a, uint64_t b, uint64_t* c) {
return _mulx_u64(a, b, (unsigned long long *)c);
}
clang trunk, -O2 -march=skylake:
mulx(unsigned long, unsigned long, unsigned long*):
#
@mulx(unsigned long, unsigned long, unsigned long*)
mov rcx, rdx
mov rax, rsi
mul rdi
mov qword ptr [rcx], rdx
ret
<a href="https://godbolt.org/z/rsGQWm">https://godbolt.org/z/rsGQWm</a></pre>
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