Improved cost model for FDIV and FSQRT, by Andrew Tischenko
There is a bug describing poor cost model for floating point operations:
Bug 29083 - [X86][SSE] Improve costs for floating point operations. This
patch is the second one in series of patches dealing with cost model.
Differential Revision: https://reviews.llvm.org/D25722
llvm-svn: 285564
diff --git a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
index d115eb2..afa8e00 100644
--- a/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
+++ b/llvm/lib/Target/X86/X86TargetTransformInfo.cpp
@@ -324,6 +324,12 @@
{ ISD::SRA, MVT::v16i16, 10 }, // extend/vpsravd/pack sequence.
{ ISD::SRA, MVT::v2i64, 4 }, // srl/xor/sub sequence.
{ ISD::SRA, MVT::v4i64, 4 }, // srl/xor/sub sequence.
+ { ISD::FDIV, MVT::f32, 7 }, // Haswell from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f32, 7 }, // Haswell from http://www.agner.org/
+ { ISD::FDIV, MVT::v8f32, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FDIV, MVT::f64, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FDIV, MVT::v2f64, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f64, 28 }, // Haswell from http://www.agner.org/
};
// Look for AVX2 lowering tricks for custom cases.
@@ -334,6 +340,12 @@
}
static const CostTblEntry AVXCustomCostTable[] = {
+ { ISD::FDIV, MVT::f32, 14 }, // SNB from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f32, 14 }, // SNB from http://www.agner.org/
+ { ISD::FDIV, MVT::v8f32, 28 }, // SNB from http://www.agner.org/
+ { ISD::FDIV, MVT::f64, 22 }, // SNB from http://www.agner.org/
+ { ISD::FDIV, MVT::v2f64, 22 }, // SNB from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f64, 44 }, // SNB from http://www.agner.org/
// Vectorizing division is a bad idea. See the SSE2 table for more comments.
{ ISD::SDIV, MVT::v32i8, 32*20 },
{ ISD::SDIV, MVT::v16i16, 16*20 },
@@ -352,6 +364,19 @@
return LT.first * Entry->Cost;
}
+ static const CostTblEntry SSE42FloatCostTable[] = {
+ { ISD::FDIV, MVT::f32, 14 }, // Nehalem from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f32, 14 }, // Nehalem from http://www.agner.org/
+ { ISD::FDIV, MVT::f64, 22 }, // Nehalem from http://www.agner.org/
+ { ISD::FDIV, MVT::v2f64, 22 }, // Nehalem from http://www.agner.org/
+ };
+
+ if (ST->hasSSE42()) {
+ if (const auto *Entry = CostTableLookup(SSE42FloatCostTable, ISD,
+ LT.second))
+ return LT.first * Entry->Cost;
+ }
+
static const CostTblEntry
SSE2UniformCostTable[] = {
// Uniform splats are cheaper for the following instructions.
@@ -469,6 +494,11 @@
{ ISD::SRA, MVT::v2i64, 12 }, // srl/xor/sub sequence.
{ ISD::SRA, MVT::v4i64, 2*12 }, // srl/xor/sub sequence.
+ { ISD::FDIV, MVT::f32, 23 }, // Pentium IV from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f32, 39 }, // Pentium IV from http://www.agner.org/
+ { ISD::FDIV, MVT::f64, 38 }, // Pentium IV from http://www.agner.org/
+ { ISD::FDIV, MVT::v2f64, 69 }, // Pentium IV from http://www.agner.org/
+
// It is not a good idea to vectorize division. We have to scalarize it and
// in the process we will often end up having to spilling regular
// registers. The overhead of division is going to dominate most kernels
@@ -533,6 +563,15 @@
!ST->hasSSE41())
return LT.first * 6;
+ static const CostTblEntry SSE1FloatCostTable[] = {
+ { ISD::FDIV, MVT::f32, 17 }, // Pentium III from http://www.agner.org/
+ { ISD::FDIV, MVT::v4f32, 34 }, // Pentium III from http://www.agner.org/
+ };
+
+ if (ST->hasSSE1())
+ if (const auto *Entry = CostTableLookup(SSE1FloatCostTable, ISD,
+ LT.second))
+ return LT.first * Entry->Cost;
// Fallback to the default implementation.
return BaseT::getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info);
}
@@ -1111,7 +1150,13 @@
{ ISD::CTTZ, MVT::v4i64, 10 },
{ ISD::CTTZ, MVT::v8i32, 14 },
{ ISD::CTTZ, MVT::v16i16, 12 },
- { ISD::CTTZ, MVT::v32i8, 9 }
+ { ISD::CTTZ, MVT::v32i8, 9 },
+ { ISD::FSQRT, MVT::f32, 7 }, // Haswell from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f32, 7 }, // Haswell from http://www.agner.org/
+ { ISD::FSQRT, MVT::v8f32, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FSQRT, MVT::f64, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FSQRT, MVT::v2f64, 14 }, // Haswell from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f64, 28 }, // Haswell from http://www.agner.org/
};
static const CostTblEntry AVX1CostTbl[] = {
{ ISD::BITREVERSE, MVT::v4i64, 10 },
@@ -1133,6 +1178,16 @@
{ ISD::CTTZ, MVT::v8i32, 28 },
{ ISD::CTTZ, MVT::v16i16, 24 },
{ ISD::CTTZ, MVT::v32i8, 18 },
+ { ISD::FSQRT, MVT::f32, 14 }, // SNB from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f32, 14 }, // SNB from http://www.agner.org/
+ { ISD::FSQRT, MVT::v8f32, 28 }, // SNB from http://www.agner.org/
+ { ISD::FSQRT, MVT::f64, 21 }, // SNB from http://www.agner.org/
+ { ISD::FSQRT, MVT::v2f64, 21 }, // SNB from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f64, 43 }, // SNB from http://www.agner.org/
+ };
+ static const CostTblEntry SSE42CostTbl[] = {
+ { ISD::FSQRT, MVT::f32, 18 }, // Nehalem from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f32, 18 }, // Nehalem from http://www.agner.org/
};
static const CostTblEntry SSSE3CostTbl[] = {
{ ISD::BITREVERSE, MVT::v2i64, 5 },
@@ -1167,7 +1222,13 @@
{ ISD::CTTZ, MVT::v2i64, 14 },
{ ISD::CTTZ, MVT::v4i32, 18 },
{ ISD::CTTZ, MVT::v8i16, 16 },
- { ISD::CTTZ, MVT::v16i8, 13 }
+ { ISD::CTTZ, MVT::v16i8, 13 },
+ { ISD::FSQRT, MVT::f64, 32 }, // Nehalem from http://www.agner.org/
+ { ISD::FSQRT, MVT::v2f64, 32 }, // Nehalem from http://www.agner.org/
+ };
+ static const CostTblEntry SSE1CostTbl[] = {
+ { ISD::FSQRT, MVT::f32, 28 }, // Pentium III from http://www.agner.org/
+ { ISD::FSQRT, MVT::v4f32, 56 }, // Pentium III from http://www.agner.org/
};
unsigned ISD = ISD::DELETED_NODE;
@@ -1189,6 +1250,9 @@
case Intrinsic::cttz:
ISD = ISD::CTTZ;
break;
+ case Intrinsic::sqrt:
+ ISD = ISD::FSQRT;
+ break;
}
// Legalize the type.
@@ -1208,6 +1272,10 @@
if (const auto *Entry = CostTableLookup(AVX1CostTbl, ISD, MTy))
return LT.first * Entry->Cost;
+ if (ST->hasSSE42())
+ if (const auto *Entry = CostTableLookup(SSE42CostTbl, ISD, MTy))
+ return LT.first * Entry->Cost;
+
if (ST->hasSSSE3())
if (const auto *Entry = CostTableLookup(SSSE3CostTbl, ISD, MTy))
return LT.first * Entry->Cost;
@@ -1216,6 +1284,10 @@
if (const auto *Entry = CostTableLookup(SSE2CostTbl, ISD, MTy))
return LT.first * Entry->Cost;
+ if (ST->hasSSE1())
+ if (const auto *Entry = CostTableLookup(SSE1CostTbl, ISD, MTy))
+ return LT.first * Entry->Cost;
+
return BaseT::getIntrinsicInstrCost(IID, RetTy, Tys, FMF);
}