[clang] [clang][bytecode] Split `InterpFrame::shrink()`/`peekData()` into slow and fast paths (PR #225761)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/225761

And move the fast path to the header file, so it can be more easily inlined.

>From da5ad68c62414b9f5e60e3021a25e7bd02270187 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Wed, 23 Sep 2026 14:52:27 +0200
Subject: [PATCH] shink()/peekData easier inlinable

---
 clang/lib/AST/ByteCode/InterpStack.cpp | 20 ++++----------------
 clang/lib/AST/ByteCode/InterpStack.h   | 24 ++++++++++++++++++++++--
 2 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/clang/lib/AST/ByteCode/InterpStack.cpp b/clang/lib/AST/ByteCode/InterpStack.cpp
index 839540a7912f87..78b74a6a60763b 100644
--- a/clang/lib/AST/ByteCode/InterpStack.cpp
+++ b/clang/lib/AST/ByteCode/InterpStack.cpp
@@ -54,12 +54,8 @@ void InterpStack::clearTo(size_t NewSize) {
   assert(size() == NewSize);
 }
 
-void *InterpStack::peekData(size_t Size) const {
-  assert(Chunk && "Stack is empty!");
-
-  if (LLVM_LIKELY(Size <= Chunk->size()))
-    return reinterpret_cast<void *>(Chunk->start() + Chunk->Size - Size);
-
+// The "slow" part of peekData().
+void *InterpStack::peekDataSlow(size_t Size) const {
   StackChunk *Ptr = Chunk;
   while (Size > Ptr->size()) {
     Size -= Ptr->size();
@@ -70,16 +66,8 @@ void *InterpStack::peekData(size_t Size) const {
   return reinterpret_cast<void *>(Ptr->start() + Ptr->Size - Size);
 }
 
-void InterpStack::shrink(size_t Size) {
-  assert(Chunk && "Chunk is empty!");
-
-  // Likely case is that we simply remove something from the current chunk.
-  if (LLVM_LIKELY(Size <= Chunk->size())) {
-    Chunk->Size -= Size;
-    StackSize -= Size;
-    return;
-  }
-
+// The "slow" part of shrink().
+void InterpStack::shrinkSlow(size_t Size) {
   while (Size > Chunk->size()) {
     Size -= Chunk->size();
     if (Chunk->Next) {
diff --git a/clang/lib/AST/ByteCode/InterpStack.h b/clang/lib/AST/ByteCode/InterpStack.h
index 2c02979ee6eec8..ce2ed787307176 100644
--- a/clang/lib/AST/ByteCode/InterpStack.h
+++ b/clang/lib/AST/ByteCode/InterpStack.h
@@ -125,10 +125,30 @@ class InterpStack final {
     return Object;
   }
 
+  void *peekDataSlow(size_t Size) const;
   /// Returns a pointer from the top of the stack.
-  void *peekData(size_t Size) const;
+  void *peekData(size_t Size) const {
+    assert(Chunk && "Stack is empty!");
+    if (LLVM_LIKELY(Size <= Chunk->size()))
+      return reinterpret_cast<void *>(Chunk->start() + Chunk->Size - Size);
+
+    return peekDataSlow(Size);
+  }
+
+  void shrinkSlow(size_t Size);
   /// Shrinks the stack.
-  void shrink(size_t Size);
+  void shrink(size_t Size) {
+    assert(Chunk && "Chunk is empty!");
+
+    // Likely case is that we simply remove something from the current chunk.
+    if (LLVM_LIKELY(Size <= Chunk->size())) {
+      Chunk->Size -= Size;
+      StackSize -= Size;
+      return;
+    }
+
+    shrinkSlow(Size);
+  }
 
   /// Allocate stack space in 1Mb chunks.
   static constexpr size_t ChunkSize = 1024 * 1024;