https://bugs.llvm.org/show_bug.cgi?id=43240
Bug ID: 43240
Summary: KNL: inline memcpy uses two ymm loads/stores instead
of one zmm load/store
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: d...@znu.io
CC: craig.top...@gmail.com, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk, spatel+l...@rotateright.com
The following code generates two ymm loads/stores instead of a single zmm
load/store. This seems specific to knl because skylake-avx512 and
icelake-client both generate the correct code. And yes, this example is derived
from test/CodeGen/X86/memcpy.ll.
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i1)
nounwind
define void @test(i8* nocapture %A, i8* nocapture %B) nounwind optsize
noredzone {
entry:
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %A, i8* %B, i64 64, i1 false)
ret void
}
Expected result (as seen with skylake-avx512 and icelake-client):
vmovups (%rsi), %zmm0
vmovups %zmm0, (%rdi)
retq
Actual result (as seen with knl):
vmovups (%rsi), %ymm0
vmovups 32(%rsi), %ymm1
vmovups %ymm1, 32(%rdi)
vmovups %ymm0, (%rdi)
retq
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