[CostModel][X86] Add CTPOP scalar costs (PR43656)

Add specific scalar costs for ctpop instructions, these are based on the llvm-mca's SLM throughput numbers (the oldest model we have).

For targets supporting POPCNT, we provide overrides that assume 1cy costs.

llvm-svn: 374775

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index dc58c98118f..2f4b55e8aaa 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -2103,8 +2103,17 @@ int X86TTIImpl::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
     { ISD::FSQRT,      MVT::f32,    28 }, // Pentium III from http://www.agner.org/
     { ISD::FSQRT,      MVT::v4f32,  56 }, // Pentium III from http://www.agner.org/
   };
+  static const CostTblEntry POPCNT64CostTbl[] = { // 64-bit targets
+    { ISD::CTPOP,      MVT::i64,     1 },
+  };
+  static const CostTblEntry POPCNT32CostTbl[] = { // 32 or 64-bit targets
+    { ISD::CTPOP,      MVT::i32,     1 },
+    { ISD::CTPOP,      MVT::i16,     1 },
+    { ISD::CTPOP,      MVT::i8,      1 },
+  };
   static const CostTblEntry X64CostTbl[] = { // 64-bit targets
     { ISD::BITREVERSE, MVT::i64,    14 },
+    { ISD::CTPOP,      MVT::i64,    10 },
     { ISD::SADDO,      MVT::i64,     1 },
     { ISD::UADDO,      MVT::i64,     1 },
   };
@@ -2112,6 +2121,9 @@ int X86TTIImpl::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
     { ISD::BITREVERSE, MVT::i32,    14 },
     { ISD::BITREVERSE, MVT::i16,    14 },
     { ISD::BITREVERSE, MVT::i8,     11 },
+    { ISD::CTPOP,      MVT::i32,     8 },
+    { ISD::CTPOP,      MVT::i16,     9 },
+    { ISD::CTPOP,      MVT::i8,      7 },
     { ISD::SADDO,      MVT::i32,     1 },
     { ISD::SADDO,      MVT::i16,     1 },
     { ISD::SADDO,      MVT::i8,      1 },
@@ -2223,6 +2235,17 @@ int X86TTIImpl::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy,
       if (const auto *Entry = CostTableLookup(SSE1CostTbl, ISD, MTy))
         return LT.first * Entry->Cost;
 
+    if (ST->hasPOPCNT()) {
+      if (ST->is64Bit())
+        if (const auto *Entry = CostTableLookup(POPCNT64CostTbl, ISD, MTy))
+          return LT.first * Entry->Cost;
+
+      if (const auto *Entry = CostTableLookup(POPCNT32CostTbl, ISD, MTy))
+        return LT.first * Entry->Cost;
+    }
+
+    // TODO - add LZCNT and BMI (TZCNT) scalar handling
+
     if (ST->is64Bit())
       if (const auto *Entry = CostTableLookup(X64CostTbl, ISD, MTy))
         return LT.first * Entry->Cost;