https://bugs.llvm.org/show_bug.cgi?id=50985
Bug ID: 50985
Summary: mov + mul + dup instructions are used for memset
instead of just dup
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: AArch64
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected],
[email protected], [email protected],
[email protected]
https://gcc.godbolt.org/z/GfYWG5xer
#include <cstring>
void StdMemset(char* a, int b) {
memset(a, b, 64);
}
StdMemset(char*, int): // @StdMemset(char*, int)
and x8, x1, #0xff
mov x9, #72340172838076673
mul x8, x8, x9
dup v0.2d, x8
stp q0, q0, [x0, #32]
stp q0, q0, [x0]
ret
Ideally it should be
StdMemset(char*, int)
dup v0.16b, w1
stp q0, q0, [x0]
stp q0, q0, [x0, 32]
ret
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