[CostModel][X86] Add fdiv(double) throughput x87 costs for

Author: RKSimon

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -1189,6 +1189,7 @@ InstructionCost X86TTIImpl::getArithmeticInstrCost(
     { ISD::FADD, MVT::f64, {  2,  3, 1, 1 } }, // (x87)
     { ISD::FSUB, MVT::f64, {  2,  3, 1, 1 } }, // (x87)
     { ISD::FMUL, MVT::f64, {  2,  5, 1, 1 } }, // (x87)
+    { ISD::FDIV, MVT::f64, { 38 } }, // (x87)
   };
 
   if (const auto *Entry = CostTableLookup(X86CostTbl, ISD, LT.second))

llvm/test/Analysis/CostModel/X86/arith-fp.ll

@@ -527,10 +527,10 @@ define i32 @fdiv(i32 %arg) {
 ; SSE1-NEXT:  Cost Model: Found an estimated cost of 34 for instruction: %V4F32 = fdiv <4 x float> undef, undef
 ; SSE1-NEXT:  Cost Model: Found an estimated cost of 68 for instruction: %V8F32 = fdiv <8 x float> undef, undef
 ; SSE1-NEXT:  Cost Model: Found an estimated cost of 136 for instruction: %V16F32 = fdiv <16 x float> undef, undef
-; SSE1-NEXT:  Cost Model: Found an estimated cost of 2 for instruction: %F64 = fdiv double undef, undef
-; SSE1-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: %V2F64 = fdiv <2 x double> undef, undef
-; SSE1-NEXT:  Cost Model: Found an estimated cost of 8 for instruction: %V4F64 = fdiv <4 x double> undef, undef
-; SSE1-NEXT:  Cost Model: Found an estimated cost of 16 for instruction: %V8F64 = fdiv <8 x double> undef, undef
+; SSE1-NEXT:  Cost Model: Found an estimated cost of 38 for instruction: %F64 = fdiv double undef, undef
+; SSE1-NEXT:  Cost Model: Found an estimated cost of 76 for instruction: %V2F64 = fdiv <2 x double> undef, undef
+; SSE1-NEXT:  Cost Model: Found an estimated cost of 152 for instruction: %V4F64 = fdiv <4 x double> undef, undef
+; SSE1-NEXT:  Cost Model: Found an estimated cost of 304 for instruction: %V8F64 = fdiv <8 x double> undef, undef
 ; SSE1-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret i32 undef
 ;
 ; SSE2-LABEL: 'fdiv'