[LV] Restrict widest induction type to be IntegerType (NFC) (llvm#128173)

As the name of the function suggests, convertPointerToIntegerType should
return an IntegerType instead of a Type, and should only ever be called
with integer or ptr type. Fix the callers getWiderType, and
addInductionPhi to narrow the type of WidestIndTy to IntegerType,
stripping unclear casts. While at it, rename convertPointerToIntegerType
and getWiderType for clarity.

Author: artagnon

llvm/include/llvm/Transforms/Vectorize/LoopVectorizationLegality.h

@@ -308,7 +308,7 @@ class LoopVectorizationLegality {
   RecurrenceSet &getFixedOrderRecurrences() { return FixedOrderRecurrences; }
 
   /// Returns the widest induction type.
-  Type *getWidestInductionType() { return WidestIndTy; }
+  IntegerType *getWidestInductionType() { return WidestIndTy; }
 
   /// Returns True if given store is a final invariant store of one of the
   /// reductions found in the loop.
@@ -595,7 +595,7 @@ class LoopVectorizationLegality {
   RecurrenceSet FixedOrderRecurrences;
 
   /// Holds the widest induction type encountered.
-  Type *WidestIndTy = nullptr;
+  IntegerType *WidestIndTy = nullptr;
 
   /// Allowed outside users. This holds the variables that can be accessed from
   /// outside the loop.

llvm/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp

@@ -395,24 +395,25 @@ static bool isUniformLoopNest(Loop *Lp, Loop *OuterLp) {
   return true;
 }
 
-static Type *convertPointerToIntegerType(const DataLayout &DL, Type *Ty) {
+static IntegerType *getInductionIntegerTy(const DataLayout &DL, Type *Ty) {
+  assert(Ty->isIntOrPtrTy() && "Expected integer or pointer type");
+
   if (Ty->isPointerTy())
-    return DL.getIntPtrType(Ty);
+    return DL.getIntPtrType(Ty->getContext(), Ty->getPointerAddressSpace());
 
   // It is possible that char's or short's overflow when we ask for the loop's
   // trip count, work around this by changing the type size.
   if (Ty->getScalarSizeInBits() < 32)
     return Type::getInt32Ty(Ty->getContext());
 
-  return Ty;
+  return cast<IntegerType>(Ty);
 }
 
-static Type *getWiderType(const DataLayout &DL, Type *Ty0, Type *Ty1) {
-  Ty0 = convertPointerToIntegerType(DL, Ty0);
-  Ty1 = convertPointerToIntegerType(DL, Ty1);
-  if (Ty0->getScalarSizeInBits() > Ty1->getScalarSizeInBits())
-    return Ty0;
-  return Ty1;
+static IntegerType *getWiderInductionTy(const DataLayout &DL, Type *Ty0,
+                                        Type *Ty1) {
+  IntegerType *TyA = getInductionIntegerTy(DL, Ty0);
+  IntegerType *TyB = getInductionIntegerTy(DL, Ty1);
+  return TyA->getScalarSizeInBits() > TyB->getScalarSizeInBits() ? TyA : TyB;
 }
 
 /// Check that the instruction has outside loop users and is not an
@@ -692,12 +693,15 @@ void LoopVectorizationLegality::addInductionPhi(
   Type *PhiTy = Phi->getType();
   const DataLayout &DL = Phi->getDataLayout();
 
+  assert((PhiTy->isIntOrPtrTy() || PhiTy->isFloatingPointTy()) &&
+         "Expected int, ptr, or FP induction phi type");
+
   // Get the widest type.
-  if (!PhiTy->isFloatingPointTy()) {
+  if (PhiTy->isIntOrPtrTy()) {
     if (!WidestIndTy)
-      WidestIndTy = convertPointerToIntegerType(DL, PhiTy);
+      WidestIndTy = getInductionIntegerTy(DL, PhiTy);
     else
-      WidestIndTy = getWiderType(DL, PhiTy, WidestIndTy);
+      WidestIndTy = getWiderInductionTy(DL, PhiTy, WidestIndTy);
   }
 
   // Int inductions are special because we only allow one IV.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -2353,8 +2353,8 @@ static bool isIndvarOverflowCheckKnownFalse(
   // Always be conservative if we don't know the exact unroll factor.
   unsigned MaxUF = UF ? *UF : Cost->TTI.getMaxInterleaveFactor(VF);
 
-  Type *IdxTy = Cost->Legal->getWidestInductionType();
-  APInt MaxUIntTripCount = cast<IntegerType>(IdxTy)->getMask();
+  IntegerType *IdxTy = Cost->Legal->getWidestInductionType();
+  APInt MaxUIntTripCount = IdxTy->getMask();
 
   // We know the runtime overflow check is known false iff the (max) trip-count
   // is known and (max) trip-count + (VF * UF) does not overflow in the type of