http://llvm.org/bugs/show_bug.cgi?id=21139
Bug ID: 21139
Summary: New vector shuffle lowering misses to use punpckhbw
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
Created attachment 13123
--> http://llvm.org/bugs/attachment.cgi?id=13123&action=edit
IR to reproduce the problem.
With the new vector shuffle lowering we produce a sequence of a shuffle +
unpckl instead of a more direct unpckh.
To reproduce:
llc -x86-experimental-vector-shuffle-lowering=true none_shuf_unpckl_unpckh.ll
-o new.s
llc -x86-experimental-vector-shuffle-lowering=false none_shuf_unpckl_unpckh.ll
-o old.s
diff -U 10 old.s new.s
_foo: ## @foo
.cfi_startproc
## BB#0: ## %entry
+ pshufd $78, %xmm1, %xmm1 ## xmm1 = xmm1[2,3,0,1]
pxor %xmm0, %xmm0
- punpckhbw %xmm1, %xmm0 ## xmm0 =
xmm0[8],xmm1[8],xmm0[9],xmm1[9],xmm0[10],xmm1[10],xmm0[11],xmm1[11],xmm0[12],xmm1[12],xmm0[13],xmm1[13],xmm0[14],xmm1[14],xmm0[15],xmm1[15]
+ punpcklbw %xmm1, %xmm0 ## xmm0 =
xmm0[0],xmm1[0],xmm0[1],xmm1[1],xmm0[2],xmm1[2],xmm0[3],xmm1[3],xmm0[4],xmm1[4],xmm0[5],xmm1[5],xmm0[6],xmm1[6],xmm0[7],xmm1[7]
retq
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