[TTI] getScalingFactorCost should return InstructionCost::getInvalid() instead of -1. (#129802)

Historically this function return an int with negative values meaning
invalid. It was migrated to InstructionCost in 43ace8b, but the
code was not updated to return invalid cost instead of -1. In that
commit, the caller in LSR was updated to assert that the cost is valid
instead of positive. We should return invalid instead of a negative
value so LSR will assert if the cost isn't valid.

Author: topperc

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -364,7 +364,7 @@ class TargetTransformInfoImplBase {
                               Scale, AddrSpace, /*I=*/nullptr,
                               BaseOffset.getScalable()))
       return 0;
-    return -1;
+    return InstructionCost::getInvalid();
   }
 
   bool LSRWithInstrQueries() const { return false; }

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -511,7 +511,7 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     AM.ScalableOffset = BaseOffset.getScalable();
     if (getTLI()->isLegalAddressingMode(DL, AM, Ty, AddrSpace))
       return 0;
-    return -1;
+    return InstructionCost::getInvalid();
   }
 
   bool isTruncateFree(Type *Ty1, Type *Ty2) {

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -5271,7 +5271,7 @@ AArch64TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
     // Scale represents reg2 * scale, thus account for 1 if
     // it is not equal to 0 or 1.
     return AM.Scale != 0 && AM.Scale != 1;
-  return -1;
+  return InstructionCost::getInvalid();
 }
 
 bool AArch64TTIImpl::shouldTreatInstructionLikeSelect(const Instruction *I) {

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.h

@@ -450,7 +450,7 @@ class AArch64TTIImpl : public BasicTTIImplBase<AArch64TTIImpl> {
   /// mode represented by AM for this target, for a load/store
   /// of the specified type.
   /// If the AM is supported, the return value must be >= 0.
-  /// If the AM is not supported, it returns a negative value.
+  /// If the AM is not supported, it returns an invalid cost.
   InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
                                        StackOffset BaseOffset, bool HasBaseReg,
                                        int64_t Scale, unsigned AddrSpace) const;

llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp

@@ -2668,7 +2668,7 @@ InstructionCost ARMTTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
       return AM.Scale < 0 ? 1 : 0; // positive offsets execute faster
     return 0;
   }
-  return -1;
+  return InstructionCost::getInvalid();
 }
 
 bool ARMTTIImpl::hasArmWideBranch(bool Thumb) const {

llvm/lib/Target/ARM/ARMTargetTransformInfo.h

@@ -300,7 +300,7 @@ class ARMTTIImpl : public BasicTTIImplBase<ARMTTIImpl> {
   /// getScalingFactorCost - Return the cost of the scaling used in
   /// addressing mode represented by AM.
   /// If the AM is supported, the return value must be >= 0.
-  /// If the AM is not supported, the return value must be negative.
+  /// If the AM is not supported, the return value is an invalid cost.
   InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
                                        StackOffset BaseOffset, bool HasBaseReg,
                                        int64_t Scale, unsigned AddrSpace) const;

llvm/lib/Target/X86/X86TargetTransformInfo.cpp

@@ -7057,7 +7057,7 @@ InstructionCost X86TTIImpl::getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
     // Scale represents reg2 * scale, thus account for 1
     // as soon as we use a second register.
     return AM.Scale != 0;
-  return -1;
+  return InstructionCost::getInvalid();
 }
 
 InstructionCost X86TTIImpl::getBranchMispredictPenalty() const {

llvm/lib/Target/X86/X86TargetTransformInfo.h

@@ -254,7 +254,7 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
   /// mode represented by AM for this target, for a load/store
   /// of the specified type.
   /// If the AM is supported, the return value must be >= 0.
-  /// If the AM is not supported, it returns a negative value.
+  /// If the AM is not supported, it returns an invalid cost.
   InstructionCost getScalingFactorCost(Type *Ty, GlobalValue *BaseGV,
                                        StackOffset BaseOffset, bool HasBaseReg,
                                        int64_t Scale, unsigned AddrSpace) const;