[SVE] Deprecate default false variant of VectorType::get

[ctetreau]

Per recent discussions about the pace of this effort, I'll be adding a deprecated overload rather than just deleting the parameter.

[ctetreau]

As requested, deprecate it rather than immediately remove it

[ctetreau]

rebase

[ctetreau]

rebase

[ctetreau]

rebase

[ctetreau]

catch stragglers

llvm/include/llvm/IR/DerivedTypes.h

LLVM_ATTRIBUTE_DEPRECATED(
       "Calling this function via a base VectorType is deprecated. Either call "
       "getElementCount() and handle the case where Scalable is true or cast to "
       "FixedVectorType.");
 
   Type *getElementType() const { return ContainedType; }
 
   /// This static method is the primary way to construct an VectorType.
   static VectorType *get(Type *ElementType, ElementCount EC);
+
+  /// Base class getter that specifically constructs a FixedVectorType. This
+  /// function is deprecated, and will be removed after LLVM 11 ships. Since
+  /// this always returns a FixedVectorType via a base VectorType pointer,
+  /// FixedVectorType::get(Type *, unsigned) is strictly better since no cast is
+  /// required to call getNumElements() on the result.
+  LLVM_ATTRIBUTE_DEPRECATED(
+      inline static VectorType *get(Type *ElementType, unsigned NumElements),
+      "The base class version of get with the scalable argument defaulted to "
+      "false is deprecated. Either call VectorType::get(Type *, unsigned, "
+      "bool) and pass false, or call FixedVectorType::get(Type *, unsigned).");
+
   static VectorType *get(Type *ElementType, unsigned NumElements,
-                         bool Scalable = false) {
+                         bool Scalable) {
     return VectorType::get(ElementType, {NumElements, Scalable});
   }
 
   static VectorType *get(Type *ElementType, const VectorType *Other) {
     return VectorType::get(ElementType, Other->getElementCount());
   }
 
   /// This static method gets a VectorType with the same number of elements as
if (EC.Scalable)
     WithColor::warning()
         << "The code that requested the fixed number of elements has made the "
            "assumption that this vector is not scalable. This assumption was "
            "not correct, and this may lead to broken code\n";
   return EC.Min;
 #endif
 }
 
+inline VectorType *VectorType::get(Type *ElementType, unsigned NumElements) {
+  return VectorType::get(ElementType, NumElements, false);
+}
+
 bool Type::isVectorTy() const { return isa<VectorType>(this); }
 
 /// Class to represent fixed width SIMD vectors
 class FixedVectorType : public VectorType {
 protected:
   FixedVectorType(Type *ElTy, unsigned NumElts)
       : VectorType(ElTy, NumElts, FixedVectorTyID) {}