https://bugs.llvm.org/show_bug.cgi?id=40869
Bug ID: 40869
Summary: [X86] Poor broadcast folding from ext/trunc loads
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: llvm-...@redking.me.uk
CC: craig.top...@gmail.com, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk, spatel+l...@rotateright.com
e.g. (from vector-shuffle-512-v32.ll)
llc < %s -mtriple=x86_64-apple-darwin -mcpu=skx
define <32 x i16> @insert_dup_elt1_mem_v32i16_i32(i32* %ptr) #0 {
; KNL-LABEL: insert_dup_elt1_mem_v32i16_i32:
; KNL: ## %bb.0:
; KNL-NEXT: vpbroadcastw 2(%rdi), %ymm0
; KNL-NEXT: vmovdqa %ymm0, %ymm1
; KNL-NEXT: retq
;
; SKX-LABEL: insert_dup_elt1_mem_v32i16_i32:
; SKX: ## %bb.0:
; SKX-NEXT: movzwl 2(%rdi), %eax
; SKX-NEXT: vpbroadcastw %eax, %zmm0
; SKX-NEXT: retq
%tmp = load i32, i32* %ptr, align 4
%tmp1 = insertelement <4 x i32> zeroinitializer, i32 %tmp, i32 0
%tmp2 = bitcast <4 x i32> %tmp1 to <8 x i16>
%tmp3 = shufflevector <8 x i16> %tmp2, <8 x i16> undef, <32 x i32> <i32 1,
i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1,
i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1,
i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
ret <32 x i16> %tmp3
}
Notice how the KNL (AVX2) version manages to fold but SKX (AVX512BWVL) ymm
broadcasts fail.
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