[clang] [clang][bytecode] Create InterpState allocator on demand (PR #158802)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/158802

We often don't need it (especially in C), so make this optional and create it only when we first allocate something.

>From 6e55ce4b529cdb1e42fd5703cc946118ed84844d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Tue, 16 Sep 2025 08:07:41 +0200
Subject: [PATCH] [clang][bytecode] Create InterpState allocator on demand

We often don't need it (especially in C), so make this optional and
create it only when we first allocate something.
---
 clang/lib/AST/ByteCode/InterpState.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/clang/lib/AST/ByteCode/InterpState.h b/clang/lib/AST/ByteCode/InterpState.h
index e095908bce986..4e1b9aec09099 100644
--- a/clang/lib/AST/ByteCode/InterpState.h
+++ b/clang/lib/AST/ByteCode/InterpState.h
@@ -122,7 +122,9 @@ class InterpState final : public State, public SourceMapper {
   StdAllocatorCaller getStdAllocatorCaller(StringRef Name) const;
 
   void *allocate(size_t Size, unsigned Align = 8) const {
-    return Allocator.Allocate(Size, Align);
+    if (!Allocator)
+      Allocator.emplace();
+    return Allocator->Allocate(Size, Align);
   }
   template <typename T> T *allocate(size_t Num = 1) const {
     return static_cast<T *>(allocate(Num * sizeof(T), alignof(T)));
@@ -188,7 +190,7 @@ class InterpState final : public State, public SourceMapper {
   /// for.
   llvm::SmallVector<const Block *> InitializingBlocks;
 
-  mutable llvm::BumpPtrAllocator Allocator;
+  mutable std::optional<llvm::BumpPtrAllocator> Allocator;
 };
 
 class InterpStateCCOverride final {