[CostModel] Remove optional from InstructionCost::getValue()

InstructionCost is already an optional value, containing an Invalid state that
can be checked with isValid(). There is little point in returning another
optional from getValue(). Most uses do not make use of it being a
std::optional, dereferencing the value directly (either isValid has been
checked previously or the Cost is assumed to be valid). The one case that does
in AMDGPU used value_or which has been replaced by a new getValueOr(CostType)
function.

Author: davemgreen

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -1611,7 +1611,7 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
 
       // Scale the cost of the load by the fraction of legal instructions that
       // will be used.
-      Cost = divideCeil(UsedInsts.count() * *Cost.getValue(), NumLegalInsts);
+      Cost = divideCeil(UsedInsts.count() * Cost.getValue(), NumLegalInsts);
     }
 
     // Then plus the cost of interleave operation.
@@ -2879,7 +2879,7 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
           SubTp && SubTp->getElementType() == FTp->getElementType())
         return divideCeil(FTp->getNumElements(), SubTp->getNumElements());
     }
-    return *LT.first.getValue();
+    return LT.first.getValue();
   }
 
   InstructionCost getAddressComputationCost(Type *Ty, ScalarEvolution *,

llvm/include/llvm/Support/InstructionCost.h

@@ -20,7 +20,6 @@
 
 #include "llvm/Support/MathExtras.h"
 #include <limits>
-#include <optional>
 
 namespace llvm {
 
@@ -84,10 +83,14 @@ class InstructionCost {
   /// This function is intended to be used as sparingly as possible, since the
   /// class provides the full range of operator support required for arithmetic
   /// and comparisons.
-  std::optional<CostType> getValue() const {
-    if (isValid())
-      return Value;
-    return std::nullopt;
+  CostType getValue() const {
+    assert(isValid());
+    return Value;
+  }
+  CostType getValueOr(CostType Alt) const {
+    if (!isValid())
+      return Alt;
+    return Value;
   }
 
   /// For all of the arithmetic operators provided here any invalid state is

llvm/include/llvm/Transforms/Utils/UnrollLoop.h

@@ -143,7 +143,7 @@ class UnrollCostEstimator {
   /// Whether it is legal to unroll this loop.
   bool canUnroll() const;
 
-  uint64_t getRolledLoopSize() const { return *LoopSize.getValue(); }
+  uint64_t getRolledLoopSize() const { return LoopSize.getValue(); }
 
   /// Returns loop size estimation for unrolled loop, given the unrolling
   /// configuration specified by UP.

llvm/lib/Analysis/CostModel.cpp

@@ -128,8 +128,8 @@ PreservedAnalyses CostModelPrinterPass::run(Function &F,
       } else {
         InstructionCost Cost =
             getCost(Inst, OutputCostKindToTargetCostKind(CostKind), TTI, TLI);
-        if (auto CostVal = Cost.getValue())
-          OS << "Found an estimated cost of " << *CostVal;
+        if (Cost.isValid())
+          OS << "Found an estimated cost of " << Cost.getValue();
         else
           OS << "Invalid cost";
         OS << " for instruction: " << Inst << "\n";

llvm/lib/CodeGen/SelectOptimize.cpp

@@ -206,7 +206,7 @@ class SelectOptimizeImpl {
           getI()->getOpcode(), I->getType(), TargetTransformInfo::TCK_Latency,
           {TargetTransformInfo::OK_AnyValue, TargetTransformInfo::OP_None},
           {TTI::OK_UniformConstantValue, TTI::OP_PowerOf2});
-      auto TotalCost = Scaled64::get(*Cost.getValue());
+      auto TotalCost = Scaled64::get(Cost.getValue());
       if (auto *OpI = dyn_cast<Instruction>(I->getOperand(1 - CondIdx))) {
         auto It = InstCostMap.find(OpI);
         if (It != InstCostMap.end())
@@ -1380,8 +1380,8 @@ std::optional<uint64_t>
 SelectOptimizeImpl::computeInstCost(const Instruction *I) {
   InstructionCost ICost =
       TTI->getInstructionCost(I, TargetTransformInfo::TCK_Latency);
-  if (auto OC = ICost.getValue())
-    return std::optional<uint64_t>(*OC);
+  if (ICost.isValid())
+    return std::optional<uint64_t>(ICost.getValue());
   return std::nullopt;
 }
 

llvm/lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -28496,7 +28496,7 @@ bool AArch64TargetLowering::shouldLocalize(
         Imm, CI->getType(), TargetTransformInfo::TCK_CodeSize);
     assert(Cost.isValid() && "Expected a valid imm cost");
 
-    unsigned RematCost = *Cost.getValue();
+    unsigned RematCost = Cost.getValue();
     RematCost += AdditionalCost;
     Register Reg = MI.getOperand(0).getReg();
     unsigned MaxUses = maxUses(RematCost);

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -4596,7 +4596,7 @@ static bool isLoopSizeWithinBudget(Loop *L, AArch64TTIImpl &TTI,
   }
 
   if (FinalSize)
-    *FinalSize = *LoopCost.getValue();
+    *FinalSize = LoopCost.getValue();
   return true;
 }
 

llvm/lib/Target/AMDGPU/AMDGPUSplitModule.cpp

@@ -205,8 +205,7 @@ static CostType calculateFunctionCosts(GetTTIFn GetTTI, Module &M,
             TTI.getInstructionCost(&I, TargetTransformInfo::TCK_CodeSize);
         assert(Cost != InstructionCost::getMax());
         // Assume expensive if we can't tell the cost of an instruction.
-        CostType CostVal =
-            Cost.getValue().value_or(TargetTransformInfo::TCC_Expensive);
+        CostType CostVal = Cost.getValueOr(TargetTransformInfo::TCC_Expensive);
         assert((FnCost + CostVal) >= FnCost && "Overflow!");
         FnCost += CostVal;
       }

llvm/lib/Target/AMDGPU/AMDGPUTargetTransformInfo.cpp

@@ -1278,9 +1278,9 @@ static unsigned adjustInliningThresholdUsingCallee(const CallBase *CB,
   // The penalty cost is computed relative to the cost of instructions and does
   // not model any storage costs.
   adjustThreshold += std::max(0, SGPRsInUse - NrOfSGPRUntilSpill) *
-                     *ArgStackCost.getValue() * InlineConstants::getInstrCost();
+                     ArgStackCost.getValue() * InlineConstants::getInstrCost();
   adjustThreshold += std::max(0, VGPRsInUse - NrOfVGPRUntilSpill) *
-                     *ArgStackCost.getValue() * InlineConstants::getInstrCost();
+                     ArgStackCost.getValue() * InlineConstants::getInstrCost();
   return adjustThreshold;
 }
 

llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp

@@ -1100,7 +1100,7 @@ InstructionCost PPCTTIImpl::getVPMemoryOpCost(unsigned Opcode, Type *Src,
     float AlignmentProb = ((float)Alignment.value()) / DesiredAlignment.value();
     float MisalignmentProb = 1.0 - AlignmentProb;
     return (MisalignmentProb * P9PipelineFlushEstimate) +
-           (AlignmentProb * *Cost.getValue());
+           (AlignmentProb * Cost.getValue());
   }
 
   // Usually we should not get to this point, but the following is an attempt to