[llvm] [AArch64] Reduce the costs of and/or/xor reductions (PR #148553)

[David Green via llvm-commits]

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@@ -5213,34 +5213,34 @@ AArch64TTIImpl::getArithmeticReductionCost(unsigned Opcode, VectorType *ValTy,
   // XOR: llvm/test/CodeGen/AArch64/reduce-xor.ll
   // AND: llvm/test/CodeGen/AArch64/reduce-and.ll
   static const CostTblEntry CostTblNoPairwise[]{
-      {ISD::ADD, MVT::v8i8,   2},
-      {ISD::ADD, MVT::v16i8,  2},
-      {ISD::ADD, MVT::v4i16,  2},
-      {ISD::ADD, MVT::v8i16,  2},
-      {ISD::ADD, MVT::v2i32,  2},
-      {ISD::ADD, MVT::v4i32,  2},
-      {ISD::ADD, MVT::v2i64,  2},
-      {ISD::OR,  MVT::v8i8,  15},
-      {ISD::OR,  MVT::v16i8, 17},
-      {ISD::OR,  MVT::v4i16,  7},
-      {ISD::OR,  MVT::v8i16,  9},
-      {ISD::OR,  MVT::v2i32,  3},
-      {ISD::OR,  MVT::v4i32,  5},
-      {ISD::OR,  MVT::v2i64,  3},
-      {ISD::XOR, MVT::v8i8,  15},
-      {ISD::XOR, MVT::v16i8, 17},
-      {ISD::XOR, MVT::v4i16,  7},
-      {ISD::XOR, MVT::v8i16,  9},
-      {ISD::XOR, MVT::v2i32,  3},
-      {ISD::XOR, MVT::v4i32,  5},
-      {ISD::XOR, MVT::v2i64,  3},
-      {ISD::AND, MVT::v8i8,  15},
-      {ISD::AND, MVT::v16i8, 17},
-      {ISD::AND, MVT::v4i16,  7},
-      {ISD::AND, MVT::v8i16,  9},
-      {ISD::AND, MVT::v2i32,  3},
-      {ISD::AND, MVT::v4i32,  5},
-      {ISD::AND, MVT::v2i64,  3},
+      {ISD::ADD, MVT::v8i8, 2},
+      {ISD::ADD, MVT::v16i8, 2},
+      {ISD::ADD, MVT::v4i16, 2},
+      {ISD::ADD, MVT::v8i16, 2},
+      {ISD::ADD, MVT::v2i32, 2},
+      {ISD::ADD, MVT::v4i32, 2},
+      {ISD::ADD, MVT::v2i64, 2},
+      {ISD::OR, MVT::v8i8, 5},  // fmov + or_lsr + or_lsr + lsr + or
+      {ISD::OR, MVT::v16i8, 7}, // ext + orr + ^
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davemgreen wrote:

Yeah it meant a little arrow pointing to the line above, but I can see how that is confusing with xor. I've spelled it out in english. (The main reason I added the comments was to stop the formatting messing up, but hopefully they are useful).

https://github.com/llvm/llvm-project/pull/148553