[compiler-rt] [scudo] Add static vector functionality. (PR #98986)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Joshua Baehring (JoshuaMBa)

<details>
<summary>Changes</summary>

The scudo vector implementation maintains static local data before 
switching to dynamically allocated data as the array size grows.
Users of the vector can now specify the size of the static local data 
through the vector template (the default size is currently set to 
10 * sizeof(T) where T is the vector element type).

---
Full diff: https://github.com/llvm/llvm-project/pull/98986.diff


1 Files Affected:

- (modified) compiler-rt/lib/scudo/standalone/vector.h (+9-6) 


``````````diff
diff --git a/compiler-rt/lib/scudo/standalone/vector.h b/compiler-rt/lib/scudo/standalone/vector.h
index ca10cc281d770..d972ef068bee5 100644
--- a/compiler-rt/lib/scudo/standalone/vector.h
+++ b/compiler-rt/lib/scudo/standalone/vector.h
@@ -9,6 +9,7 @@
 #ifndef SCUDO_VECTOR_H_
 #define SCUDO_VECTOR_H_
 
+#include "common.h"
 #include "mem_map.h"
 
 #include <string.h>
@@ -21,7 +22,7 @@ namespace scudo {
 // implementation supports only POD types.
 //
 // NOTE: This class is not meant to be used directly, use Vector<T> instead.
-template <typename T> class VectorNoCtor {
+template <typename T, size_t StaticCapacity> class VectorNoCtor {
 public:
   T &operator[](uptr I) {
     DCHECK_LT(I, Size);
@@ -116,18 +117,19 @@ template <typename T> class VectorNoCtor {
   uptr CapacityBytes = 0;
   uptr Size = 0;
 
-  T LocalData[256 / sizeof(T)] = {};
+  T LocalData[StaticCapacity] = {};
   MemMapT ExternalBuffer;
 };
 
-template <typename T> class Vector : public VectorNoCtor<T> {
+template <typename T, size_t StaticCapacity = 10>
+class Vector : public VectorNoCtor<T, Max<size_t>(10, StaticCapacity)> {
 public:
-  constexpr Vector() { VectorNoCtor<T>::init(); }
+  constexpr Vector() { VectorNoCtor<T, StaticCapacity>::init(); }
   explicit Vector(uptr Count) {
-    VectorNoCtor<T>::init(Count);
+    VectorNoCtor<T, StaticCapacity>::init(Count);
     this->resize(Count);
   }
-  ~Vector() { VectorNoCtor<T>::destroy(); }
+  ~Vector() { VectorNoCtor<T, StaticCapacity>::destroy(); }
   // Disallow copies and moves.
   Vector(const Vector &) = delete;
   Vector &operator=(const Vector &) = delete;
@@ -138,3 +140,4 @@ template <typename T> class Vector : public VectorNoCtor<T> {
 } // namespace scudo
 
 #endif // SCUDO_VECTOR_H_
+

``````````

</details>


https://github.com/llvm/llvm-project/pull/98986