[wpiutil] Vendor llvm and update to 13.0.0 (#4224)

wpiutil/src/main/native/cpp/llvm/SmallVector.cpp

@@ -1,9 +1,8 @@
 //===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
@@ -12,21 +11,99 @@
 //===----------------------------------------------------------------------===//
 
 #include "wpi/SmallVector.h"
-#include "wpi/MemAlloc.h"
+#include <cstdint>
+#ifdef LLVM_ENABLE_EXCEPTIONS
+#include <stdexcept>
+#endif
 using namespace wpi;
 
-/// grow_pod - This is an implementation of the grow() method which only works
-/// on POD-like datatypes and is out of line to reduce code duplication.
-void SmallVectorBase::grow_pod(void *FirstEl, size_t MinCapacity,
-                               size_t TSize) {
-  // Ensure we can fit the new capacity in 32 bits.
-  if (MinCapacity > UINT32_MAX)
-    report_bad_alloc_error("SmallVector capacity overflow during allocation");
+// Check that no bytes are wasted and everything is well-aligned.
+namespace {
+struct Struct16B {
+  alignas(16) void *X;
+};
+struct Struct32B {
+  alignas(32) void *X;
+};
+}
+static_assert(sizeof(SmallVector<void *, 0>) ==
+                  sizeof(unsigned) * 2 + sizeof(void *),
+              "wasted space in SmallVector size 0");
+static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
+              "wrong alignment for 16-byte aligned T");
+static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
+              "wrong alignment for 32-byte aligned T");
+static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
+              "missing padding for 16-byte aligned T");
+static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
+              "missing padding for 32-byte aligned T");
+static_assert(sizeof(SmallVector<void *, 1>) ==
+                  sizeof(unsigned) * 2 + sizeof(void *) * 2,
+              "wasted space in SmallVector size 1");
 
-  size_t NewCapacity = 2 * capacity() + 1; // Always grow.
-  NewCapacity =
-      std::min(std::max(NewCapacity, MinCapacity), size_t(UINT32_MAX));
+/// Report that MinSize doesn't fit into this vector's size type. Throws
+/// std::length_error or calls report_fatal_error.
+LLVM_ATTRIBUTE_NORETURN
+static void report_size_overflow(size_t MinSize, size_t MaxSize);
+static void report_size_overflow(size_t MinSize, size_t MaxSize) {
+  std::string Reason = "SmallVector unable to grow. Requested capacity (" +
+                       std::to_string(MinSize) +
+                       ") is larger than maximum value for size type (" +
+                       std::to_string(MaxSize) + ")";
+#ifdef LLVM_ENABLE_EXCEPTIONS
+  throw std::length_error(Reason);
+#else
+  report_fatal_error(Reason);
+#endif
+}
 
+/// Report that this vector is already at maximum capacity. Throws
+/// std::length_error or calls report_fatal_error.
+LLVM_ATTRIBUTE_NORETURN static void report_at_maximum_capacity(size_t MaxSize);
+static void report_at_maximum_capacity(size_t MaxSize) {
+  std::string Reason =
+      "SmallVector capacity unable to grow. Already at maximum size " +
+      std::to_string(MaxSize);
+#ifdef LLVM_ENABLE_EXCEPTIONS
+  throw std::length_error(Reason);
+#else
+  report_fatal_error(Reason);
+#endif
+}
+
+// Note: Moving this function into the header may cause performance regression.
+static size_t getNewCapacity(size_t MinSize, size_t TSize, size_t OldCapacity) {
+  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.
+  if (MinSize > MaxSize)
+    report_size_overflow(MinSize, MaxSize);
+
+  // Ensure we can meet the guarantee of space for at least one more element.
+  // The above check alone will not catch the case where grow is called with a
+  // default MinSize of 0, but the current capacity cannot be increased.
+  // This is only going to be applicable when the capacity is 32 bit.
+  if (OldCapacity == MaxSize)
+    report_at_maximum_capacity(MaxSize);
+
+  // In theory 2*capacity can overflow if the capacity is 64 bit, but the
+  // original capacity would never be large enough for this to be a problem.
+  size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
+  return (std::min)((std::max)(NewCapacity, MinSize), MaxSize);
+}
+
+// Note: Moving this function into the header may cause performance regression.
+void *SmallVectorBase::mallocForGrow(size_t MinSize, size_t TSize,
+                                             size_t &NewCapacity) {
+  NewCapacity = getNewCapacity(MinSize, TSize, this->capacity());
+  return wpi::safe_malloc(NewCapacity * TSize);
+}
+
+// Note: Moving this function into the header may cause performance regression.
+void SmallVectorBase::grow_pod(void *FirstEl, size_t MinSize,
+                                       size_t TSize) {
+  size_t NewCapacity = getNewCapacity(MinSize, TSize, this->capacity());
   void *NewElts;
   if (BeginX == FirstEl) {
     NewElts = safe_malloc(NewCapacity * TSize);