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[X86] LowerShift - don't prematurely lower to x86 vector shift imm instructions
When splitting 2 unique amount shifts to shuffle(shift(x,c1),shift(x,c2)), don't use getTargetVShiftByConstNode directly to lower, use generic shifts to ensure we make use of any further canonicalization: shl(X,1) to add(X,X) etc. - this can have notably better throughput on some x86 targets. Noticed on llvm#120270
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5 files changed

+22
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‎llvm/lib/Target/X86/X86ISelLowering.cpp‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -30100,10 +30100,10 @@ static SDValue LowerShift(SDValue Op, const X86Subtarget &Subtarget,
3010030100
auto *Cst2 = dyn_cast<ConstantSDNode>(Amt2);
3010130101
if (Cst1 && Cst2 && Cst1->getAPIntValue().ult(EltSizeInBits) &&
3010230102
Cst2->getAPIntValue().ult(EltSizeInBits)) {
30103-
SDValue Shift1 = getTargetVShiftByConstNode(X86OpcI, dl, VT, R,
30104-
Cst1->getZExtValue(), DAG);
30105-
SDValue Shift2 = getTargetVShiftByConstNode(X86OpcI, dl, VT, R,
30106-
Cst2->getZExtValue(), DAG);
30103+
SDValue Shift1 = DAG.getNode(
30104+
Opc, dl, VT, R, DAG.getConstant(Cst1->getZExtValue(), dl, VT));
30105+
SDValue Shift2 = DAG.getNode(
30106+
Opc, dl, VT, R, DAG.getConstant(Cst2->getZExtValue(), dl, VT));
3010730107
return DAG.getVectorShuffle(VT, dl, Shift1, Shift2, ShuffleMask);
3010830108
}
3010930109
}

‎llvm/test/CodeGen/X86/combine-sdiv.ll‎

Lines changed: 8 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -2190,7 +2190,7 @@ define <16 x i8> @non_splat_minus_one_divisor_1(<16 x i8> %A) {
21902190
; SSE41-NEXT: pxor %xmm4, %xmm4
21912191
; SSE41-NEXT: punpcklbw {{.*#+}} xmm4 = xmm4[0],xmm3[0],xmm4[1],xmm3[1],xmm4[2],xmm3[2],xmm4[3],xmm3[3],xmm4[4],xmm3[4],xmm4[5],xmm3[5],xmm4[6],xmm3[6],xmm4[7],xmm3[7]
21922192
; SSE41-NEXT: pmovzxbw {{.*#+}} xmm2 = xmm3[0],zero,xmm3[1],zero,xmm3[2],zero,xmm3[3],zero,xmm3[4],zero,xmm3[5],zero,xmm3[6],zero,xmm3[7],zero
2193-
; SSE41-NEXT: psllw $1, %xmm2
2193+
; SSE41-NEXT: paddw %xmm2, %xmm2
21942194
; SSE41-NEXT: pblendw {{.*#+}} xmm2 = xmm4[0,1],xmm2[2],xmm4[3,4,5],xmm2[6],xmm4[7]
21952195
; SSE41-NEXT: psrlw $8, %xmm2
21962196
; SSE41-NEXT: punpckhbw {{.*#+}} xmm3 = xmm3[8],xmm0[8],xmm3[9],xmm0[9],xmm3[10],xmm0[10],xmm3[11],xmm0[11],xmm3[12],xmm0[12],xmm3[13],xmm0[13],xmm3[14],xmm0[14],xmm3[15],xmm0[15]
@@ -2202,9 +2202,9 @@ define <16 x i8> @non_splat_minus_one_divisor_1(<16 x i8> %A) {
22022202
; SSE41-NEXT: punpckhbw {{.*#+}} xmm0 = xmm0[8],xmm2[8],xmm0[9],xmm2[9],xmm0[10],xmm2[10],xmm0[11],xmm2[11],xmm0[12],xmm2[12],xmm0[13],xmm2[13],xmm0[14],xmm2[14],xmm0[15],xmm2[15]
22032203
; SSE41-NEXT: psraw $8, %xmm0
22042204
; SSE41-NEXT: movdqa %xmm0, %xmm3
2205-
; SSE41-NEXT: psllw $1, %xmm3
2206-
; SSE41-NEXT: psllw $7, %xmm0
2207-
; SSE41-NEXT: pblendw {{.*#+}} xmm0 = xmm0[0,1,2,3,4],xmm3[5],xmm0[6],xmm3[7]
2205+
; SSE41-NEXT: psllw $7, %xmm3
2206+
; SSE41-NEXT: paddw %xmm0, %xmm0
2207+
; SSE41-NEXT: pblendw {{.*#+}} xmm0 = xmm3[0,1,2,3,4],xmm0[5],xmm3[6],xmm0[7]
22082208
; SSE41-NEXT: psrlw $8, %xmm0
22092209
; SSE41-NEXT: punpcklbw {{.*#+}} xmm2 = xmm2[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
22102210
; SSE41-NEXT: psraw $8, %xmm2
@@ -2225,7 +2225,7 @@ define <16 x i8> @non_splat_minus_one_divisor_1(<16 x i8> %A) {
22252225
; AVX1-NEXT: vpcmpgtb %xmm0, %xmm1, %xmm2
22262226
; AVX1-NEXT: vpunpcklbw {{.*#+}} xmm3 = xmm1[0],xmm2[0],xmm1[1],xmm2[1],xmm1[2],xmm2[2],xmm1[3],xmm2[3],xmm1[4],xmm2[4],xmm1[5],xmm2[5],xmm1[6],xmm2[6],xmm1[7],xmm2[7]
22272227
; AVX1-NEXT: vpmovzxbw {{.*#+}} xmm4 = xmm2[0],zero,xmm2[1],zero,xmm2[2],zero,xmm2[3],zero,xmm2[4],zero,xmm2[5],zero,xmm2[6],zero,xmm2[7],zero
2228-
; AVX1-NEXT: vpsllw $1, %xmm4, %xmm4
2228+
; AVX1-NEXT: vpaddw %xmm4, %xmm4, %xmm4
22292229
; AVX1-NEXT: vpblendw {{.*#+}} xmm3 = xmm3[0,1],xmm4[2],xmm3[3,4,5],xmm4[6],xmm3[7]
22302230
; AVX1-NEXT: vpsrlw $8, %xmm3, %xmm3
22312231
; AVX1-NEXT: vpunpckhbw {{.*#+}} xmm1 = xmm2[8],xmm1[8],xmm2[9],xmm1[9],xmm2[10],xmm1[10],xmm2[11],xmm1[11],xmm2[12],xmm1[12],xmm2[13],xmm1[13],xmm2[14],xmm1[14],xmm2[15],xmm1[15]
@@ -2235,9 +2235,9 @@ define <16 x i8> @non_splat_minus_one_divisor_1(<16 x i8> %A) {
22352235
; AVX1-NEXT: vpaddb %xmm1, %xmm0, %xmm1
22362236
; AVX1-NEXT: vpunpckhbw {{.*#+}} xmm2 = xmm1[8,8,9,9,10,10,11,11,12,12,13,13,14,14,15,15]
22372237
; AVX1-NEXT: vpsraw $8, %xmm2, %xmm2
2238-
; AVX1-NEXT: vpsllw $1, %xmm2, %xmm3
2239-
; AVX1-NEXT: vpsllw $7, %xmm2, %xmm2
2240-
; AVX1-NEXT: vpblendw {{.*#+}} xmm2 = xmm2[0,1,2,3,4],xmm3[5],xmm2[6],xmm3[7]
2238+
; AVX1-NEXT: vpsllw $7, %xmm2, %xmm3
2239+
; AVX1-NEXT: vpaddw %xmm2, %xmm2, %xmm2
2240+
; AVX1-NEXT: vpblendw {{.*#+}} xmm2 = xmm3[0,1,2,3,4],xmm2[5],xmm3[6],xmm2[7]
22412241
; AVX1-NEXT: vpsrlw $8, %xmm2, %xmm2
22422242
; AVX1-NEXT: vpunpcklbw {{.*#+}} xmm1 = xmm1[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
22432243
; AVX1-NEXT: vpsraw $8, %xmm1, %xmm1

‎llvm/test/CodeGen/X86/lower-vec-shift.ll‎

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -265,11 +265,11 @@ define <16 x i16> @test11(<16 x i16> %a) {
265265
; AVX1-LABEL: test11:
266266
; AVX1: # %bb.0:
267267
; AVX1-NEXT: vextractf128 $1, %ymm0, %xmm1
268-
; AVX1-NEXT: vpsllw $1, %xmm1, %xmm2
269-
; AVX1-NEXT: vpsllw $3, %xmm1, %xmm1
270-
; AVX1-NEXT: vpblendw {{.*#+}} xmm1 = xmm1[0,1,2],xmm2[3,4,5],xmm1[6],xmm2[7]
268+
; AVX1-NEXT: vpsllw $3, %xmm1, %xmm2
269+
; AVX1-NEXT: vpaddw %xmm1, %xmm1, %xmm1
270+
; AVX1-NEXT: vpblendw {{.*#+}} xmm1 = xmm2[0,1,2],xmm1[3,4,5],xmm2[6],xmm1[7]
271271
; AVX1-NEXT: vpsllw $3, %xmm0, %xmm2
272-
; AVX1-NEXT: vpsllw $1, %xmm0, %xmm0
272+
; AVX1-NEXT: vpaddw %xmm0, %xmm0, %xmm0
273273
; AVX1-NEXT: vpblendw {{.*#+}} xmm0 = xmm0[0],xmm2[1],xmm0[2,3,4],xmm2[5,6,7]
274274
; AVX1-NEXT: vinsertf128 $1, %xmm1, %ymm0, %ymm0
275275
; AVX1-NEXT: retq
@@ -294,18 +294,18 @@ define <16 x i16> @test12(<16 x i16> %a) {
294294
; AVX1: # %bb.0:
295295
; AVX1-NEXT: vextractf128 $1, %ymm0, %xmm1
296296
; AVX1-NEXT: vpsllw $3, %xmm1, %xmm2
297-
; AVX1-NEXT: vpsllw $1, %xmm1, %xmm1
297+
; AVX1-NEXT: vpaddw %xmm1, %xmm1, %xmm1
298298
; AVX1-NEXT: vpblendw {{.*#+}} xmm1 = xmm1[0],xmm2[1],xmm1[2,3,4],xmm2[5,6,7]
299299
; AVX1-NEXT: vpsllw $3, %xmm0, %xmm2
300-
; AVX1-NEXT: vpsllw $1, %xmm0, %xmm0
300+
; AVX1-NEXT: vpaddw %xmm0, %xmm0, %xmm0
301301
; AVX1-NEXT: vpblendw {{.*#+}} xmm0 = xmm0[0],xmm2[1],xmm0[2,3,4],xmm2[5,6,7]
302302
; AVX1-NEXT: vinsertf128 $1, %xmm1, %ymm0, %ymm0
303303
; AVX1-NEXT: retq
304304
;
305305
; AVX2-LABEL: test12:
306306
; AVX2: # %bb.0:
307307
; AVX2-NEXT: vpsllw $3, %ymm0, %ymm1
308-
; AVX2-NEXT: vpsllw $1, %ymm0, %ymm0
308+
; AVX2-NEXT: vpaddw %ymm0, %ymm0, %ymm0
309309
; AVX2-NEXT: vpblendw {{.*#+}} ymm0 = ymm0[0],ymm1[1],ymm0[2,3,4],ymm1[5,6,7],ymm0[8],ymm1[9],ymm0[10,11,12],ymm1[13,14,15]
310310
; AVX2-NEXT: retq
311311
%lshr = shl <16 x i16> %a, <i16 1, i16 3, i16 1, i16 1, i16 1, i16 3, i16 3, i16 3, i16 1, i16 3, i16 1, i16 1, i16 1, i16 3, i16 3, i16 3>

‎llvm/test/CodeGen/X86/vec_shift6.ll‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -68,14 +68,14 @@ define <4 x i32> @test4(<4 x i32> %a) {
6868
; SSE2-LABEL: test4:
6969
; SSE2: # %bb.0:
7070
; SSE2-NEXT: movdqa %xmm0, %xmm1
71-
; SSE2-NEXT: pslld $1, %xmm1
71+
; SSE2-NEXT: paddd %xmm0, %xmm1
7272
; SSE2-NEXT: shufps {{.*#+}} xmm0 = xmm0[0,1],xmm1[2,3]
7373
; SSE2-NEXT: retq
7474
;
7575
; SSE41-LABEL: test4:
7676
; SSE41: # %bb.0:
7777
; SSE41-NEXT: movdqa %xmm0, %xmm1
78-
; SSE41-NEXT: pslld $1, %xmm1
78+
; SSE41-NEXT: paddd %xmm0, %xmm1
7979
; SSE41-NEXT: pblendw {{.*#+}} xmm0 = xmm0[0,1,2,3],xmm1[4,5,6,7]
8080
; SSE41-NEXT: retq
8181
;

‎llvm/test/CodeGen/X86/widen_arith-4.ll‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -65,7 +65,7 @@ define void @update(ptr %dst, ptr %src, i32 %n) nounwind {
6565
; SSE41-NEXT: psubw %xmm0, %xmm1
6666
; SSE41-NEXT: movdqa %xmm1, %xmm2
6767
; SSE41-NEXT: psllw $2, %xmm2
68-
; SSE41-NEXT: psllw $1, %xmm1
68+
; SSE41-NEXT: paddw %xmm1, %xmm1
6969
; SSE41-NEXT: pblendw {{.*#+}} xmm2 = xmm1[0],xmm2[1],xmm1[2,3,4,5,6,7]
7070
; SSE41-NEXT: pextrw $4, %xmm1, 8(%rcx,%rax)
7171
; SSE41-NEXT: movq %xmm2, (%rcx,%rax)

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