[X86][Costmodel] Load/store i16 Stride=3 VF=2 interleaving costs

The only sched models that for cpu's that support avx2
but not avx512 are: haswell, broadwell, skylake, zen1-3

For load we have:
https://godbolt.org/z/xnE988aej - for intels `Block RThroughput: =5.0`; for ryzens, `Block RThroughput: <=2.5`
So pick cost of `5`.

For store we have:
https://godbolt.org/z/rMGT31Tnh - for intels `Block RThroughput: =4.0`; for ryzens, `Block RThroughput: <=2.0`
So pick cost of `4`.

I'm directly using the shuffling asm the llc produced,
without any manual fixups that may be needed
to ensure sequential execution.

Reviewed By: RKSimon

Differential Revision: https://reviews.llvm.org/D111014

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -5100,6 +5100,8 @@ InstructionCost X86TTIImpl::getInterleavedMemoryOpCostAVX2(
       {3, MVT::v16i8, 11}, // (load 48i8 and) deinterleave into 3 x 16i8
       {3, MVT::v32i8, 14}, // (load 96i8 and) deinterleave into 3 x 32i8
 
+      {3, MVT::v2i16, 5},  // (load 6i16 and) deinterleave into 3 x 2i16
+
       {3, MVT::v8i32, 17}, // (load 24i32 and) deinterleave into 3 x 8i32
 
       {4, MVT::v2i8, 4},  // (load 8i8 and) deinterleave into 4 x 2i8
@@ -5158,6 +5160,8 @@ InstructionCost X86TTIImpl::getInterleavedMemoryOpCostAVX2(
       {3, MVT::v16i8, 11}, // interleave 3 x 16i8 into 48i8 (and store)
       {3, MVT::v32i8, 13}, // interleave 3 x 32i8 into 96i8 (and store)
 
+      {3, MVT::v2i16, 4},   // interleave 3 x 2i16 into 6i16 (and store)
+
       {4, MVT::v2i8, 4},  // interleave 4 x 2i8 into 8i8 (and store)
       {4, MVT::v4i8, 4},   // interleave 4 x 4i8 into 16i8 (and store)
       {4, MVT::v8i8, 4},  // interleave 4 x 8i8 into 32i8 (and store)

llvm/test/Analysis/CostModel/X86/interleaved-load-i16-stride-3.ll

@@ -26,7 +26,7 @@ target triple = "x86_64-unknown-linux-gnu"
 ; AVX1: LV: Found an estimated cost of 258 for VF 32 For instruction:   %v0 = load i16, i16* %in0, align 2
 ;
 ; AVX2: LV: Found an estimated cost of 1 for VF 1 For instruction:   %v0 = load i16, i16* %in0, align 2
-; AVX2: LV: Found an estimated cost of 15 for VF 2 For instruction:   %v0 = load i16, i16* %in0, align 2
+; AVX2: LV: Found an estimated cost of 8 for VF 2 For instruction:   %v0 = load i16, i16* %in0, align 2
 ; AVX2: LV: Found an estimated cost of 31 for VF 4 For instruction:   %v0 = load i16, i16* %in0, align 2
 ; AVX2: LV: Found an estimated cost of 58 for VF 8 For instruction:   %v0 = load i16, i16* %in0, align 2
 ; AVX2: LV: Found an estimated cost of 129 for VF 16 For instruction:   %v0 = load i16, i16* %in0, align 2

llvm/test/Analysis/CostModel/X86/interleaved-store-i16-stride-3.ll

@@ -26,7 +26,7 @@ target triple = "x86_64-unknown-linux-gnu"
 ; AVX1: LV: Found an estimated cost of 258 for VF 32 For instruction:   store i16 %v2, i16* %out2, align 2
 ;
 ; AVX2: LV: Found an estimated cost of 1 for VF 1 For instruction:   store i16 %v2, i16* %out2, align 2
-; AVX2: LV: Found an estimated cost of 15 for VF 2 For instruction:   store i16 %v2, i16* %out2, align 2
+; AVX2: LV: Found an estimated cost of 7 for VF 2 For instruction:   store i16 %v2, i16* %out2, align 2
 ; AVX2: LV: Found an estimated cost of 30 for VF 4 For instruction:   store i16 %v2, i16* %out2, align 2
 ; AVX2: LV: Found an estimated cost of 53 for VF 8 For instruction:   store i16 %v2, i16* %out2, align 2
 ; AVX2: LV: Found an estimated cost of 129 for VF 16 For instruction:   store i16 %v2, i16* %out2, align 2