[PATCH] D78127: [SVE] Move VectorType::getNumElements() into FixedVectorType

[Christopher Tetreault via Phabricator via llvm-commits]

ctetreau created this revision.
Herald added subscribers: llvm-commits, psnobl, rkruppe, tschuett.
Herald added a reviewer: efriedma.
Herald added a project: LLVM.
ctetreau added a parent revision: D77587: [SVE] Add new VectorType subclasses.

Move getNumElements() into FixedVectorType in order to eliminate the
class of bugs where a scalable vector is accidentally treated like a
fixed length vector.

See: http://lists.llvm.org/pipermail/llvm-dev/2020-March/139811.html


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D78127

Files:
  llvm/include/llvm/IR/DerivedTypes.h


Index: llvm/include/llvm/IR/DerivedTypes.h
===================================================================
--- llvm/include/llvm/IR/DerivedTypes.h
+++ llvm/include/llvm/IR/DerivedTypes.h
@@ -414,11 +414,6 @@
   VectorType(const VectorType &) = delete;
   VectorType &operator=(const VectorType &) = delete;
 
-  /// Get the number of elements in this vector. It does not make sense to call
-  /// this function on a scalable vector, and this will be moved into
-  /// FixedVectorType in a future commit
-  unsigned getNumElements() const { return EC.Min; }
-
   Type *getElementType() const { return ContainedType; }
 
   /// This static method is the primary way to construct an VectorType.
@@ -499,8 +494,6 @@
   /// input type and the same element type.
   static VectorType *getDoubleElementsVectorType(VectorType *VTy) {
     auto EltCnt = VTy->getElementCount();
-    assert((VTy->getNumElements() * 2ull) <= UINT_MAX &&
-           "Too many elements in vector");
     return VectorType::get(VTy->getElementType(), EltCnt*2);
   }
 
@@ -510,8 +503,6 @@
   /// Return an ElementCount instance to represent the (possibly scalable)
   /// number of elements in the vector.
   ElementCount getElementCount() const {
-    uint64_t MinimumEltCnt = getNumElements();
-    assert(MinimumEltCnt <= UINT_MAX && "Too many elements in vector");
     return EC;
   }
 
@@ -533,6 +524,9 @@
 public:
   static FixedVectorType *get(Type *ElementType, unsigned NumElts);
 
+  /// Get the number of elements in this vector.
+  unsigned getNumElements() const { return getElementCount().Min; }
+
   static bool classof(const Type *T) {
     return T->getTypeID() == FixedVectorTyID;
   }


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