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

[via cfe-commits]

https://github.com/smanna12 created https://github.com/llvm/llvm-project/pull/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.

>From b00a7bcc442274d59426fb0198caedd798ef2458 Mon Sep 17 00:00:00 2001
From: "Manna, Soumi" <soumi.manna at intel.com>
Date: Wed, 27 Mar 2024 08:01:54 -0700
Subject: [PATCH] [CLANG] Fix potential integer overflow value in
 getRVVTypeSize()

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.
---
 clang/lib/AST/ASTContext.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 20a5ecc99e44a7..c90fafb6f653d0 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;
 }