[CLANG] Fix potential integer overflow value in getRVVTypeSize() (#86810)

In getRVVTypeSize(clang::ASTContext &, clang::BuiltinType const *)
potential integer overflow occurs on expression VScale->first * MinElts
with type unsigned int (32 bits, unsigned) is evaluated using 32-bit
arithmetic, and then used in a context that expects an expression of
type uint64_t (64 bits, unsigned).

To avoid integer overflow, this patch changes the types of variables
MinElts and EltSize to uint64_t instead of the cast.

The change matches what was originally done in https://github.com/llvm/llvm-project/commit/7372c0d46d2185017c509eb30910b102b4f9cdaa. Looks like the revert happened in https://github.com/llvm/llvm-project/commit/c92ad411f2f94d8521cd18abcb37285f9a390ecb

1 files changed, 2 insertions, 2 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 20a5ecc..c90fafb 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -9600,11 +9600,11 @@ static uint64_t getRVVTypeSize(ASTContext &Context, const BuiltinType *Ty) {
 
   ASTContext::BuiltinVectorTypeInfo Info = Context.getBuiltinVectorTypeInfo(Ty);
 
-  unsigned EltSize = Context.getTypeSize(Info.ElementType);
+  uint64_t EltSize = Context.getTypeSize(Info.ElementType);
   if (Info.ElementType == Context.BoolTy)
     EltSize = 1;
 
-  unsigned MinElts = Info.EC.getKnownMinValue();
+  uint64_t MinElts = Info.EC.getKnownMinValue();
   return VScale->first * MinElts * EltSize;
 }