1 files changed, 87 insertions, 17 deletions
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index 9fa911967e7..be9caba506d 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -417,29 +417,99 @@ unsigned X86TTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index,
   }
 
   if (Kind == SK_Alternate) {
-    static const CostTblEntry<MVT::SimpleValueType> X86AltShuffleTbl[] = {
-        // Alt shuffle cost table for X86. Cost is the number of instructions
-        // required to create the shuffled vector.
+    // 64-bit packed float vectors (v2f32) are widened to type v4f32.
+    // 64-bit packed integer vectors (v2i32) are promoted to type v2i64.
+    std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);
+
+    // The backend knows how to generate a single VEX.256 version of
+    // instruction VPBLENDW if the target supports AVX2.
+    if (ST->hasAVX2() && LT.second == MVT::v16i16)
+      return LT.first;
 
-        {ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
-        {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
-        {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
+    static const CostTblEntry<MVT::SimpleValueType> AVXAltShuffleTbl[] = {
+      {ISD::VECTOR_SHUFFLE, MVT::v4i64, 1},  // vblendpd
+      {ISD::VECTOR_SHUFFLE, MVT::v4f64, 1},  // vblendpd
 
-        {ISD::VECTOR_SHUFFLE, MVT::v2i32, 2},
-        {ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
-        {ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
+      {ISD::VECTOR_SHUFFLE, MVT::v8i32, 1},  // vblendps
+      {ISD::VECTOR_SHUFFLE, MVT::v8f32, 1},  // vblendps
 
-        {ISD::VECTOR_SHUFFLE, MVT::v4i16, 8},
-        {ISD::VECTOR_SHUFFLE, MVT::v8i16, 8},
+      // This shuffle is custom lowered into a sequence of:
+      //  2x  vextractf128 , 2x vpblendw , 1x vinsertf128
+      {ISD::VECTOR_SHUFFLE, MVT::v16i16, 5},
 
-        {ISD::VECTOR_SHUFFLE, MVT::v16i8, 49}};
+      // This shuffle is custom lowered into a long sequence of:
+      //  2x vextractf128 , 4x vpshufb , 2x vpor ,  1x vinsertf128
+      {ISD::VECTOR_SHUFFLE, MVT::v32i8, 9}
+    };
 
-    std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(Tp);
+    if (ST->hasAVX()) {
+      int Idx = CostTableLookup(AVXAltShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second);
+      if (Idx != -1)
+        return LT.first * AVXAltShuffleTbl[Idx].Cost;
+    }
+
+    static const CostTblEntry<MVT::SimpleValueType> SSE41AltShuffleTbl[] = {
+      // These are lowered into movsd.
+      {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
+      {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
+
+      // packed float vectors with four elements are lowered into BLENDI dag
+      // nodes. A v4i32/v4f32 BLENDI generates a single 'blendps'/'blendpd'.
+      {ISD::VECTOR_SHUFFLE, MVT::v4i32, 1},
+      {ISD::VECTOR_SHUFFLE, MVT::v4f32, 1},
+
+      // This shuffle generates a single pshufw.
+      {ISD::VECTOR_SHUFFLE, MVT::v8i16, 1},
+
+      // There is no instruction that matches a v16i8 alternate shuffle.
+      // The backend will expand it into the sequence 'pshufb + pshufb + or'.
+      {ISD::VECTOR_SHUFFLE, MVT::v16i8, 3}
+    };
+
+    if (ST->hasSSE41()) {
+      int Idx = CostTableLookup(SSE41AltShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second);
+      if (Idx != -1)
+        return LT.first * SSE41AltShuffleTbl[Idx].Cost;
+    }
+
+    static const CostTblEntry<MVT::SimpleValueType> SSSE3AltShuffleTbl[] = {
+      {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},  // movsd
+      {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},  // movsd
+
+      // SSE3 doesn't have 'blendps'. The following shuffles are expanded into
+      // the sequence 'shufps + pshufd'
+      {ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
+      {ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
+
+      {ISD::VECTOR_SHUFFLE, MVT::v8i16, 3}, // pshufb + pshufb + or
+      {ISD::VECTOR_SHUFFLE, MVT::v16i8, 3}  // pshufb + pshufb + or
+    };
+ 
+    if (ST->hasSSSE3()) {
+      int Idx = CostTableLookup(SSSE3AltShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second);
+      if (Idx != -1)
+        return LT.first * SSSE3AltShuffleTbl[Idx].Cost;
+    }
 
-    int Idx = CostTableLookup(X86AltShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second);
-    if (Idx == -1)
-      return TargetTransformInfo::getShuffleCost(Kind, Tp, Index, SubTp);
-    return LT.first * X86AltShuffleTbl[Idx].Cost;
+    static const CostTblEntry<MVT::SimpleValueType> SSEAltShuffleTbl[] = {
+      {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},  // movsd
+      {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},  // movsd
+
+      {ISD::VECTOR_SHUFFLE, MVT::v4i32, 2}, // shufps + pshufd
+      {ISD::VECTOR_SHUFFLE, MVT::v4f32, 2}, // shufps + pshufd
+ 
+      // This is expanded into a long sequence of four extract + four insert.
+      {ISD::VECTOR_SHUFFLE, MVT::v8i16, 8}, // 4 x pextrw + 4 pinsrw.
+
+      // 8 x (pinsrw + pextrw + and + movb + movzb + or)
+      {ISD::VECTOR_SHUFFLE, MVT::v16i8, 48}
+    };
+
+    // Fall-back (SSE3 and SSE2). 
+    int Idx = CostTableLookup(SSEAltShuffleTbl, ISD::VECTOR_SHUFFLE, LT.second);
+    if (Idx != -1)
+      return LT.first * SSEAltShuffleTbl[Idx].Cost;
+    return TargetTransformInfo::getShuffleCost(Kind, Tp, Index, SubTp);
   }
 
   return TargetTransformInfo::getShuffleCost(Kind, Tp, Index, SubTp);