1 files changed, 192 insertions, 0 deletions
diff --git a/llvm/lib/IR/User.cpp b/llvm/lib/IR/User.cpp
new file mode 100644
index 0000000000000..33a3686c94a13
--- /dev/null
+++ b/llvm/lib/IR/User.cpp
@@ -0,0 +1,192 @@
+//===-- User.cpp - Implement the User class -------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/User.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/GlobalValue.h"
+
+namespace llvm {
+class BasicBlock;
+
+//===----------------------------------------------------------------------===//
+//                                 User Class
+//===----------------------------------------------------------------------===//
+
+void User::replaceUsesOfWith(Value *From, Value *To) {
+  if (From == To) return;   // Duh what?
+
+  assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
+         "Cannot call User::replaceUsesOfWith on a constant!");
+
+  for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
+    if (getOperand(i) == From) {  // Is This operand is pointing to oldval?
+      // The side effects of this setOperand call include linking to
+      // "To", adding "this" to the uses list of To, and
+      // most importantly, removing "this" from the use list of "From".
+      setOperand(i, To); // Fix it now...
+    }
+}
+
+//===----------------------------------------------------------------------===//
+//                         User allocHungoffUses Implementation
+//===----------------------------------------------------------------------===//
+
+void User::allocHungoffUses(unsigned N, bool IsPhi) {
+  assert(HasHungOffUses && "alloc must have hung off uses");
+
+  static_assert(alignof(Use) >= alignof(Use::UserRef),
+                "Alignment is insufficient for 'hung-off-uses' pieces");
+  static_assert(alignof(Use::UserRef) >= alignof(BasicBlock *),
+                "Alignment is insufficient for 'hung-off-uses' pieces");
+
+  // Allocate the array of Uses, followed by a pointer (with bottom bit set) to
+  // the User.
+  size_t size = N * sizeof(Use) + sizeof(Use::UserRef);
+  if (IsPhi)
+    size += N * sizeof(BasicBlock *);
+  Use *Begin = static_cast<Use*>(::operator new(size));
+  Use *End = Begin + N;
+  (void) new(End) Use::UserRef(const_cast<User*>(this), 1);
+  setOperandList(Use::initTags(Begin, End));
+}
+
+void User::growHungoffUses(unsigned NewNumUses, bool IsPhi) {
+  assert(HasHungOffUses && "realloc must have hung off uses");
+
+  unsigned OldNumUses = getNumOperands();
+
+  // We don't support shrinking the number of uses.  We wouldn't have enough
+  // space to copy the old uses in to the new space.
+  assert(NewNumUses > OldNumUses && "realloc must grow num uses");
+
+  Use *OldOps = getOperandList();
+  allocHungoffUses(NewNumUses, IsPhi);
+  Use *NewOps = getOperandList();
+
+  // Now copy from the old operands list to the new one.
+  std::copy(OldOps, OldOps + OldNumUses, NewOps);
+
+  // If this is a Phi, then we need to copy the BB pointers too.
+  if (IsPhi) {
+    auto *OldPtr =
+        reinterpret_cast<char *>(OldOps + OldNumUses) + sizeof(Use::UserRef);
+    auto *NewPtr =
+        reinterpret_cast<char *>(NewOps + NewNumUses) + sizeof(Use::UserRef);
+    std::copy(OldPtr, OldPtr + (OldNumUses * sizeof(BasicBlock *)), NewPtr);
+  }
+  Use::zap(OldOps, OldOps + OldNumUses, true);
+}
+
+
+// This is a private struct used by `User` to track the co-allocated descriptor
+// section.
+struct DescriptorInfo {
+  intptr_t SizeInBytes;
+};
+
+ArrayRef<const uint8_t> User::getDescriptor() const {
+  auto MutableARef = const_cast<User *>(this)->getDescriptor();
+  return {MutableARef.begin(), MutableARef.end()};
+}
+
+MutableArrayRef<uint8_t> User::getDescriptor() {
+  assert(HasDescriptor && "Don't call otherwise!");
+  assert(!HasHungOffUses && "Invariant!");
+
+  auto *DI = reinterpret_cast<DescriptorInfo *>(getIntrusiveOperands()) - 1;
+  assert(DI->SizeInBytes != 0 && "Should not have had a descriptor otherwise!");
+
+  return MutableArrayRef<uint8_t>(
+      reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes, DI->SizeInBytes);
+}
+
+//===----------------------------------------------------------------------===//
+//                         User operator new Implementations
+//===----------------------------------------------------------------------===//
+
+void *User::allocateFixedOperandUser(size_t Size, unsigned Us,
+                                     unsigned DescBytes) {
+  assert(Us < (1u << NumUserOperandsBits) && "Too many operands");
+
+  static_assert(sizeof(DescriptorInfo) % sizeof(void *) == 0, "Required below");
+
+  unsigned DescBytesToAllocate =
+      DescBytes == 0 ? 0 : (DescBytes + sizeof(DescriptorInfo));
+  assert(DescBytesToAllocate % sizeof(void *) == 0 &&
+         "We need this to satisfy alignment constraints for Uses");
+
+  uint8_t *Storage = static_cast<uint8_t *>(
+      ::operator new(Size + sizeof(Use) * Us + DescBytesToAllocate));
+  Use *Start = reinterpret_cast<Use *>(Storage + DescBytesToAllocate);
+  Use *End = Start + Us;
+  User *Obj = reinterpret_cast<User*>(End);
+  Obj->NumUserOperands = Us;
+  Obj->HasHungOffUses = false;
+  Obj->HasDescriptor = DescBytes != 0;
+  Use::initTags(Start, End);
+
+  if (DescBytes != 0) {
+    auto *DescInfo = reinterpret_cast<DescriptorInfo *>(Storage + DescBytes);
+    DescInfo->SizeInBytes = DescBytes;
+  }
+
+  return Obj;
+}
+
+void *User::operator new(size_t Size, unsigned Us) {
+  return allocateFixedOperandUser(Size, Us, 0);
+}
+
+void *User::operator new(size_t Size, unsigned Us, unsigned DescBytes) {
+  return allocateFixedOperandUser(Size, Us, DescBytes);
+}
+
+void *User::operator new(size_t Size) {
+  // Allocate space for a single Use*
+  void *Storage = ::operator new(Size + sizeof(Use *));
+  Use **HungOffOperandList = static_cast<Use **>(Storage);
+  User *Obj = reinterpret_cast<User *>(HungOffOperandList + 1);
+  Obj->NumUserOperands = 0;
+  Obj->HasHungOffUses = true;
+  Obj->HasDescriptor = false;
+  *HungOffOperandList = nullptr;
+  return Obj;
+}
+
+//===----------------------------------------------------------------------===//
+//                         User operator delete Implementation
+//===----------------------------------------------------------------------===//
+
+void User::operator delete(void *Usr) {
+  // Hung off uses use a single Use* before the User, while other subclasses
+  // use a Use[] allocated prior to the user.
+  User *Obj = static_cast<User *>(Usr);
+  if (Obj->HasHungOffUses) {
+    assert(!Obj->HasDescriptor && "not supported!");
+
+    Use **HungOffOperandList = static_cast<Use **>(Usr) - 1;
+    // drop the hung off uses.
+    Use::zap(*HungOffOperandList, *HungOffOperandList + Obj->NumUserOperands,
+             /* Delete */ true);
+    ::operator delete(HungOffOperandList);
+  } else if (Obj->HasDescriptor) {
+    Use *UseBegin = static_cast<Use *>(Usr) - Obj->NumUserOperands;
+    Use::zap(UseBegin, UseBegin + Obj->NumUserOperands, /* Delete */ false);
+
+    auto *DI = reinterpret_cast<DescriptorInfo *>(UseBegin) - 1;
+    uint8_t *Storage = reinterpret_cast<uint8_t *>(DI) - DI->SizeInBytes;
+    ::operator delete(Storage);
+  } else {
+    Use *Storage = static_cast<Use *>(Usr) - Obj->NumUserOperands;
+    Use::zap(Storage, Storage + Obj->NumUserOperands,
+             /* Delete */ false);
+    ::operator delete(Storage);
+  }
+}
+
+} // End llvm namespace