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Revert rG057db2002bb3: [X86] combineAndnp - constant fold ANDNP(C,X) -> AND(~C,X)

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If the LHS op has a single use then using the more general AND op is likely to allow commutation, load folding, generic folds etc.

Reverted due to reports from @alexfh about it causing an infinite loop (repro still pending).
This commit is contained in:
Simon Pilgrim 2022-07-01 10:36:01 +01:00
parent 36c9e9968a
commit 26708fa166
3 changed files with 20 additions and 28 deletions
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13
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -50981,19 +50981,8 @@ static SDValue combineAndnp(SDNode *N, SelectionDAG &DAG,
if (SDValue Not = IsNOT(N0, DAG))
return DAG.getNode(ISD::AND, SDLoc(N), VT, DAG.getBitcast(VT, Not), N1);
// Constant fold NOT(N0) to allow us to use AND.
// TODO: Constant fold NOT(N0) to allow us to use AND.
// TODO: Do this in IsNOT with suitable oneuse checks?
if (getTargetConstantFromNode(N0) && N0->hasOneUse()) {
APInt UndefElts;
SmallVector<APInt, 32> EltBits;
if (getTargetConstantBitsFromNode(N0, VT.getScalarSizeInBits(), UndefElts,
EltBits)) {
for (APInt &Elt : EltBits)
Elt = ~Elt;
SDValue Not = getConstVector(EltBits, UndefElts, VT, DAG, SDLoc(N));
return DAG.getNode(ISD::AND, SDLoc(N), VT, Not, N1);
}
}
// Attempt to recursively combine a bitmask ANDNP with shuffles.
if (VT.isVector() && (VT.getScalarSizeInBits() % 8) == 0) {

25
llvm/test/CodeGen/X86/combine-udiv.ll
View File

@ -688,18 +688,19 @@ define <16 x i8> @combine_vec_udiv_nonuniform4(<16 x i8> %x) {
define <8 x i16> @pr38477(<8 x i16> %a0) {
; SSE2-LABEL: pr38477:
; SSE2: # %bb.0:
; SSE2-NEXT: movdqa {{.*#+}} xmm1 = [0,4957,57457,4103,16385,35545,2048,2115]
; SSE2-NEXT: pmulhuw %xmm0, %xmm1
; SSE2-NEXT: movdqa %xmm0, %xmm2
; SSE2-NEXT: psubw %xmm1, %xmm2
; SSE2-NEXT: pmulhuw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2
; SSE2-NEXT: paddw %xmm1, %xmm2
; SSE2-NEXT: movdqa {{.*#+}} xmm1 = [65535,65535,65535,65535,65535,65535,0,65535]
; SSE2-NEXT: pandn %xmm2, %xmm1
; SSE2-NEXT: pmulhuw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm2
; SSE2-NEXT: pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; SSE2-NEXT: por %xmm1, %xmm0
; SSE2-NEXT: por %xmm2, %xmm0
; SSE2-NEXT: movdqa {{.*#+}} xmm2 = [0,4957,57457,4103,16385,35545,2048,2115]
; SSE2-NEXT: pmulhuw %xmm0, %xmm2
; SSE2-NEXT: movdqa {{.*#+}} xmm1 = [0,65535,65535,65535,65535,65535,65535,65535]
; SSE2-NEXT: pandn %xmm0, %xmm1
; SSE2-NEXT: psubw %xmm2, %xmm0
; SSE2-NEXT: pmulhuw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; SSE2-NEXT: paddw %xmm2, %xmm0
; SSE2-NEXT: movdqa {{.*#+}} xmm2 = [65535,65535,65535,65535,65535,65535,0,65535]
; SSE2-NEXT: pandn %xmm0, %xmm2
; SSE2-NEXT: pmulhuw {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; SSE2-NEXT: por %xmm2, %xmm1
; SSE2-NEXT: por %xmm0, %xmm1
; SSE2-NEXT: movdqa %xmm1, %xmm0
; SSE2-NEXT: retq
;
; SSE41-LABEL: pr38477:

10
llvm/test/CodeGen/X86/insert-into-constant-vector.ll
View File

@ -13,15 +13,17 @@
define <16 x i8> @elt0_v16i8(i8 %x) {
; X86-SSE2-LABEL: elt0_v16i8:
; X86-SSE2: # %bb.0:
; X86-SSE2-NEXT: movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
; X86-SSE2-NEXT: andps {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
; X86-SSE2-NEXT: movss {{.*#+}} xmm1 = mem[0],zero,zero,zero
; X86-SSE2-NEXT: movaps {{.*#+}} xmm0 = [0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255]
; X86-SSE2-NEXT: andnps %xmm1, %xmm0
; X86-SSE2-NEXT: orps {{\.?LCPI[0-9]+_[0-9]+}}, %xmm0
; X86-SSE2-NEXT: retl
;
; X64-SSE2-LABEL: elt0_v16i8:
; X64-SSE2: # %bb.0:
; X64-SSE2-NEXT: movd %edi, %xmm0
; X64-SSE2-NEXT: pand {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; X64-SSE2-NEXT: movd %edi, %xmm1
; X64-SSE2-NEXT: movdqa {{.*#+}} xmm0 = [0,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255]
; X64-SSE2-NEXT: pandn %xmm1, %xmm0
; X64-SSE2-NEXT: por {{\.?LCPI[0-9]+_[0-9]+}}(%rip), %xmm0
; X64-SSE2-NEXT: retq
;