From b887e8f6e34e2ff2a3ad69f67f84f49ceb1f455e Mon Sep 17 00:00:00 2001
From: PJ Reiniger <pj.reiniger@gmail.com>
Date: Thu, 5 May 2022 23:18:34 -0400
Subject: [PATCH 15/31] Detemplatize small vector base

---
 llvm/include/llvm/ADT/SmallVector.h | 21 +++++++-----------
 llvm/lib/Support/SmallVector.cpp    | 34 +++++------------------------
 2 files changed, 13 insertions(+), 42 deletions(-)

diff --git a/llvm/include/llvm/ADT/SmallVector.h b/llvm/include/llvm/ADT/SmallVector.h
index 690d512a43c8..695015ae3248 100644
--- a/llvm/include/llvm/ADT/SmallVector.h
+++ b/llvm/include/llvm/ADT/SmallVector.h
@@ -50,14 +50,14 @@ namespace llvm {
 /// Using 64 bit size is desirable for cases like SmallVector<char>, where a
 /// 32 bit size would limit the vector to ~4GB. SmallVectors are used for
 /// buffering bitcode output - which can exceed 4GB.
-template <class Size_T> class SmallVectorBase {
+class SmallVectorBase {
 protected:
   void *BeginX;
-  Size_T Size = 0, Capacity;
+  unsigned Size = 0, Capacity;
 
   /// The maximum value of the Size_T used.
   static constexpr size_t SizeTypeMax() {
-    return (std::numeric_limits<Size_T>::max)();
+    return (std::numeric_limits<unsigned>::max)();
   }
 
   SmallVectorBase() = delete;
@@ -95,15 +95,10 @@ public:
   }
 };
 
-template <class T>
-using SmallVectorSizeType =
-    typename std::conditional<sizeof(T) < 4 && sizeof(void *) >= 8, uint64_t,
-                              uint32_t>::type;
-
 /// Figure out the offset of the first element.
 template <class T, typename = void> struct SmallVectorAlignmentAndSize {
-  alignas(SmallVectorBase<SmallVectorSizeType<T>>) char Base[sizeof(
-      SmallVectorBase<SmallVectorSizeType<T>>)];
+  alignas(SmallVectorBase) char Base[sizeof(
+      SmallVectorBase)];
   alignas(T) char FirstEl[sizeof(T)];
 };
 
@@ -112,8 +107,8 @@ template <class T, typename = void> struct SmallVectorAlignmentAndSize {
 /// to avoid unnecessarily requiring T to be complete.
 template <typename T, typename = void>
 class SmallVectorTemplateCommon
-    : public SmallVectorBase<SmallVectorSizeType<T>> {
-  using Base = SmallVectorBase<SmallVectorSizeType<T>>;
+    : public SmallVectorBase {
+  using Base = SmallVectorBase;
 
   /// Find the address of the first element.  For this pointer math to be valid
   /// with small-size of 0 for T with lots of alignment, it's important that
@@ -360,7 +355,7 @@ protected:
   /// in \p NewCapacity. This is the first section of \a grow().
   T *mallocForGrow(size_t MinSize, size_t &NewCapacity) {
     return static_cast<T *>(
-        SmallVectorBase<SmallVectorSizeType<T>>::mallocForGrow(
+        SmallVectorBase::mallocForGrow(
             MinSize, sizeof(T), NewCapacity));
   }
 
diff --git a/llvm/lib/Support/SmallVector.cpp b/llvm/lib/Support/SmallVector.cpp
index 26901fe97d20..3fc16097bd30 100644
--- a/llvm/lib/Support/SmallVector.cpp
+++ b/llvm/lib/Support/SmallVector.cpp
@@ -41,10 +41,6 @@ static_assert(sizeof(SmallVector<void *, 1>) ==
                   sizeof(unsigned) * 2 + sizeof(void *) * 2,
               "wasted space in SmallVector size 1");
 
-static_assert(sizeof(SmallVector<char, 0>) ==
-                  sizeof(void *) * 2 + sizeof(void *),
-              "1 byte elements have word-sized type for size and capacity");
-
 /// Report that MinSize doesn't fit into this vector's size type. Throws
 /// std::length_error or calls report_fatal_error.
 LLVM_ATTRIBUTE_NORETURN
@@ -76,9 +72,8 @@ static void report_at_maximum_capacity(size_t MaxSize) {
 }
 
 // Note: Moving this function into the header may cause performance regression.
-template <class Size_T>
 static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
-  constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();
+  constexpr size_t MaxSize = std::numeric_limits<unsigned>::max();
 
   // Ensure we can fit the new capacity.
   // This is only going to be applicable when the capacity is 32 bit.
@@ -99,18 +94,16 @@ static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
 }
 
 // Note: Moving this function into the header may cause performance regression.
-template <class Size_T>
-void *SmallVectorBase<Size_T>::mallocForGrow(size_t MinSize, size_t TSize,
+void *SmallVectorBase::mallocForGrow(size_t MinSize, size_t TSize,
                                              size_t &NewCapacity) {
-  NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
+  NewCapacity = getNewCapacity(MinSize, TSize, this->capacity());
   return llvm::safe_malloc(NewCapacity * TSize);
 }
 
 // Note: Moving this function into the header may cause performance regression.
-template <class Size_T>
-void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
+void SmallVectorBase::grow_pod(void *FirstEl, size_t MinSize,
                                        size_t TSize) {
-  size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
+  size_t NewCapacity = getNewCapacity(MinSize, TSize, this->capacity());
   void *NewElts;
   if (BeginX == FirstEl) {
     NewElts = safe_malloc(NewCapacity * TSize);
@@ -125,20 +118,3 @@ void SmallVectorBase<Size_T>::grow_pod(void *FirstEl, size_t MinSize,
   this->BeginX = NewElts;
   this->Capacity = NewCapacity;
 }
-
-template class llvm::SmallVectorBase<uint32_t>;
-
-// Disable the uint64_t instantiation for 32-bit builds.
-// Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
-// This instantiation will never be used in 32-bit builds, and will cause
-// warnings when sizeof(Size_T) > sizeof(size_t).
-#if SIZE_MAX > UINT32_MAX
-template class llvm::SmallVectorBase<uint64_t>;
-
-// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
-static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
-              "Expected SmallVectorBase<uint64_t> variant to be in use.");
-#else
-static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint32_t),
-              "Expected SmallVectorBase<uint32_t> variant to be in use.");
-#endif
-- 
2.20.1.windows.1