[llvm] [CostModel][X86] Reduce cost of pre-SSE41 select shuffle (PR #207400)

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git-clang-format --diff origin/main HEAD --extensions cpp -- llvm/lib/Target/X86/X86TargetTransformInfo.cpp --diff_from_common_commit
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``````````diff
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index 2cb99d0c2..99a4210b9 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -2276,8 +2276,10 @@ InstructionCost X86TTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
       {TTI::SK_Reverse, MVT::v4i32, {1, 1, 1, 1}}, // pshufd
       {TTI::SK_Reverse, MVT::v8i16, {2, 3, 3, 3}}, // pshuflw + pshufhw + pshufd
       {TTI::SK_Reverse, MVT::v8f16, {2, 3, 3, 3}}, // pshuflw + pshufhw + pshufd
-      {TTI::SK_Reverse, MVT::v16i8, {5, 6,11,11}}, // 2*pshuflw + 2*pshufhw
-                                                   // + 2*pshufd + 2*unpck + packus
+      {TTI::SK_Reverse,
+       MVT::v16i8,
+       {5, 6, 11, 11}}, // 2*pshuflw + 2*pshufhw
+                        // + 2*pshufd + 2*unpck + packus
 
       {TTI::SK_Select, MVT::v2i64, {1, 1, 1, 1}}, // movsd
       {TTI::SK_Select, MVT::v2f64, {1, 1, 1, 1}}, // movsd
@@ -2296,16 +2298,24 @@ InstructionCost X86TTIImpl::getShuffleCost(TTI::ShuffleKind Kind,
       {TTI::SK_PermuteSingleSrc, MVT::v2f64, {1, 1, 1, 1}}, // shufpd
       {TTI::SK_PermuteSingleSrc, MVT::v2i64, {1, 1, 1, 1}}, // pshufd
       {TTI::SK_PermuteSingleSrc, MVT::v4i32, {1, 1, 1, 1}}, // pshufd
-      {TTI::SK_PermuteSingleSrc, MVT::v8i16, {3, 5, 5, 5}}, // 2*pshuflw + 2*pshufhw
-                                                            // + pshufd/unpck
-      {TTI::SK_PermuteSingleSrc, MVT::v8f16, {3, 5, 5, 5}}, // 2*pshuflw + 2*pshufhw
-                                                            // + pshufd/unpck
-      {TTI::SK_PermuteSingleSrc, MVT::v16i8, {8, 10, 10, 10}}, // 2*pshuflw + 2*pshufhw
-                                                               // + 2*pshufd + 2*unpck + 2*packus
-
-      {TTI::SK_PermuteTwoSrc, MVT::v2f64, {1, 1, 1, 1}},     // shufpd
-      {TTI::SK_PermuteTwoSrc, MVT::v2i64, {1, 1, 1, 1}},     // shufpd
-      {TTI::SK_PermuteTwoSrc, MVT::v4i32, {2, 2, 2, 2}},     // 2*{unpck,movsd,pshufd}
+      {TTI::SK_PermuteSingleSrc,
+       MVT::v8i16,
+       {3, 5, 5, 5}}, // 2*pshuflw + 2*pshufhw
+                      // + pshufd/unpck
+      {TTI::SK_PermuteSingleSrc,
+       MVT::v8f16,
+       {3, 5, 5, 5}}, // 2*pshuflw + 2*pshufhw
+                      // + pshufd/unpck
+      {TTI::SK_PermuteSingleSrc,
+       MVT::v16i8,
+       {8, 10, 10, 10}}, // 2*pshuflw + 2*pshufhw
+                         // + 2*pshufd + 2*unpck + 2*packus
+
+      {TTI::SK_PermuteTwoSrc, MVT::v2f64, {1, 1, 1, 1}}, // shufpd
+      {TTI::SK_PermuteTwoSrc, MVT::v2i64, {1, 1, 1, 1}}, // shufpd
+      {TTI::SK_PermuteTwoSrc,
+       MVT::v4i32,
+       {2, 2, 2, 2}}, // 2*{unpck,movsd,pshufd}
       {TTI::SK_PermuteTwoSrc, MVT::v8i16, {6, 8, 8, 8}},     // blend+permute
       {TTI::SK_PermuteTwoSrc, MVT::v8f16, {6, 8, 8, 8}},     // blend+permute
       {TTI::SK_PermuteTwoSrc, MVT::v16i8, {11, 13, 13, 13}}, // blend+permute

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https://github.com/llvm/llvm-project/pull/207400