[clang] [clang][Interp] Implement __builtin_bit_cast (PR #68288)

[via cfe-commits]

Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/68288 at github.com>


================
@@ -1561,6 +1576,59 @@ template <PrimType TIn, PrimType TOut> bool Cast(InterpState &S, CodePtr OpPC) {
   return true;
 }
 
+template <PrimType Name, class ToT = typename PrimConv<Name>::T>
+bool BitCast(InterpState &S, CodePtr OpPC, bool TargetIsUCharOrByte) {
+  const Pointer &FromPtr = S.Stk.pop<Pointer>();
+
+  size_t BuffSize = ToT::valueReprBytes(S.getCtx());
+  std::vector<std::byte> Buff(BuffSize);
----------------
cor3ntin wrote:

an llvm small vector (with a buffer of ~8) would avoid almost all allocation here

https://github.com/llvm/llvm-project/pull/68288