[AArch64] Extend costs for fptoi.sat intrinsics.

Most of these bring the costs in line with the code generation. The f16 costs
without FullFP16 are usually converted to f32. Extended v2f32->v2f64 vectors
similarly use fcvtl + fcvt. As a backup we use the costs similar to the target
independent code, which should give a relatively high cost.

Author: davemgreen

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -748,22 +748,44 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
     // output are the same, or we are using cvt f64->i32 or f32->i64.
     if ((LT.second == MVT::f32 || LT.second == MVT::f64 ||
          LT.second == MVT::v2f32 || LT.second == MVT::v4f32 ||
-         LT.second == MVT::v2f64) &&
-        (LT.second.getScalarSizeInBits() == MTy.getScalarSizeInBits() ||
-         (LT.second == MVT::f64 && MTy == MVT::i32) ||
-         (LT.second == MVT::f32 && MTy == MVT::i64)))
-      return LT.first;
-    // Similarly for fp16 sizes
-    if (ST->hasFullFP16() &&
-        ((LT.second == MVT::f16 && MTy == MVT::i32) ||
-         ((LT.second == MVT::v4f16 || LT.second == MVT::v8f16) &&
-          (LT.second.getScalarSizeInBits() == MTy.getScalarSizeInBits()))))
+         LT.second == MVT::v2f64)) {
+      if ((LT.second.getScalarSizeInBits() == MTy.getScalarSizeInBits() ||
+           (LT.second == MVT::f64 && MTy == MVT::i32) ||
+           (LT.second == MVT::f32 && MTy == MVT::i64)))
+        return LT.first;
+      // Extending vector types v2f32->v2i64, fcvtl*2 + fcvt*2
+      if (LT.second.getScalarType() == MVT::f32 && MTy.isFixedLengthVector() &&
+          MTy.getScalarSizeInBits() == 64)
+        return LT.first * (MTy.getVectorNumElements() > 2 ? 4 : 2);
+    }
+    // Similarly for fp16 sizes. Without FullFP16 we generally need to fcvt to
+    // f32.
+    if (LT.second.getScalarType() == MVT::f16 && !ST->hasFullFP16())
+      return LT.first + getIntrinsicInstrCost(
+                            {ICA.getID(),
+                             RetTy,
+                             {ICA.getArgTypes()[0]->getWithNewType(
+                                 Type::getFloatTy(RetTy->getContext()))}},
+                            CostKind);
+    if ((LT.second == MVT::f16 && MTy == MVT::i32) ||
+        (LT.second == MVT::f16 && MTy == MVT::i64) ||
+        ((LT.second == MVT::v4f16 || LT.second == MVT::v8f16) &&
+         (LT.second.getScalarSizeInBits() == MTy.getScalarSizeInBits())))
       return LT.first;
-
-    // Otherwise we use a legal convert followed by a min+max
+    // Extending vector types v8f16->v8i32, fcvtl*2 + fcvt*2
+    if (LT.second.getScalarType() == MVT::f16 && MTy.isFixedLengthVector() &&
+        MTy.getScalarSizeInBits() == 32)
+      return LT.first * (MTy.getVectorNumElements() > 4 ? 4 : 2);
+    // Extending vector types v8f16->v8i32. These current scalarize but the
+    // codegen could be better.
+    if (LT.second.getScalarType() == MVT::f16 && MTy.isFixedLengthVector() &&
+        MTy.getScalarSizeInBits() == 64)
+      return MTy.getVectorNumElements() * 3;
+
+    // If we can we use a legal convert followed by a min+max
     if ((LT.second.getScalarType() == MVT::f32 ||
          LT.second.getScalarType() == MVT::f64 ||
-         (ST->hasFullFP16() && LT.second.getScalarType() == MVT::f16)) &&
+         LT.second.getScalarType() == MVT::f16) &&
         LT.second.getScalarSizeInBits() >= MTy.getScalarSizeInBits()) {
       Type *LegalTy =
           Type::getIntNTy(RetTy->getContext(), LT.second.getScalarSizeInBits());
@@ -776,9 +798,33 @@ AArch64TTIImpl::getIntrinsicInstrCost(const IntrinsicCostAttributes &ICA,
       IntrinsicCostAttributes Attrs2(IsSigned ? Intrinsic::smax : Intrinsic::umax,
                                     LegalTy, {LegalTy, LegalTy});
       Cost += getIntrinsicInstrCost(Attrs2, CostKind);
-      return LT.first * Cost;
+      return LT.first * Cost +
+             ((LT.second.getScalarType() != MVT::f16 || ST->hasFullFP16()) ? 0
+                                                                           : 1);
     }
-    break;
+    // Otherwise we need to follow the default expansion that clamps the value
+    // using a float min/max with a fcmp+sel for nan handling when signed.
+    Type *FPTy = ICA.getArgTypes()[0]->getScalarType();
+    RetTy = RetTy->getScalarType();
+    if (LT.second.isVector()) {
+      FPTy = VectorType::get(FPTy, LT.second.getVectorElementCount());
+      RetTy = VectorType::get(RetTy, LT.second.getVectorElementCount());
+    }
+    IntrinsicCostAttributes Attrs1(Intrinsic::minnum, FPTy, {FPTy, FPTy});
+    InstructionCost Cost = getIntrinsicInstrCost(Attrs1, CostKind);
+    IntrinsicCostAttributes Attrs2(Intrinsic::maxnum, FPTy, {FPTy, FPTy});
+    Cost += getIntrinsicInstrCost(Attrs2, CostKind);
+    Cost +=
+        getCastInstrCost(IsSigned ? Instruction::FPToSI : Instruction::FPToUI,
+                         RetTy, FPTy, TTI::CastContextHint::None, CostKind);
+    if (IsSigned) {
+      Type *CondTy = RetTy->getWithNewBitWidth(1);
+      Cost += getCmpSelInstrCost(BinaryOperator::FCmp, FPTy, CondTy,
+                                 CmpInst::FCMP_UNO, CostKind);
+      Cost += getCmpSelInstrCost(BinaryOperator::Select, RetTy, CondTy,
+                                 CmpInst::FCMP_UNO, CostKind);
+    }
+    return LT.first * Cost;
   }
   case Intrinsic::fshl:
   case Intrinsic::fshr: {