[clang] [clang][Interp] Implement dynamic memory allocation handling (PR #70306)

[via cfe-commits]

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@@ -1990,6 +2011,79 @@ inline bool OffsetOf(InterpState &S, CodePtr OpPC, const OffsetOfExpr *E) {
   return true;
 }
 
+inline bool Alloc(InterpState &S, CodePtr OpPC, const Descriptor *Desc) {
+  assert(Desc);
+
+  if (!CheckDynamicMemoryAllocation(S, OpPC))
+    return false;
+
+  DynamicAllocator &Allocator = S.getAllocator();
+  Block *B = Allocator.allocate(Desc);
+
+  S.Stk.push<Pointer>(B, sizeof(InlineDescriptor));
+
+  return true;
+}
+
+template <PrimType Name, class SizeT = typename PrimConv<Name>::T>
+inline bool AllocN(InterpState &S, CodePtr OpPC, PrimType T,
+                   const Expr *Source) {
+  if (!CheckDynamicMemoryAllocation(S, OpPC))
+    return false;
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cor3ntin wrote:

I think we want similar diagnostics as we have in `EvalInfo::CheckArraySize` here - ie for some large `NumElements` we should fail

https://github.com/llvm/llvm-project/pull/70306