Merge "Update prebuilt Clang to r353983." into p9.0HEADp9.0-backupp9.0

1 files changed, 84 insertions, 0 deletions

diff --git a/clang-r353983/include/llvm/Transforms/Utils/GlobalStatus.h b/clang-r353983/include/llvm/Transforms/Utils/GlobalStatus.h
new file mode 100644
index 00000000..519593c9
--- /dev/null
+++ b/clang-r353983/include/llvm/Transforms/Utils/GlobalStatus.h
@@ -0,0 +1,84 @@
+//===- GlobalStatus.h - Compute status info for globals ---------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H
+#define LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H
+
+#include "llvm/Support/AtomicOrdering.h"
+
+namespace llvm {
+
+class Constant;
+class Function;
+class Value;
+
+/// It is safe to destroy a constant iff it is only used by constants itself.
+/// Note that constants cannot be cyclic, so this test is pretty easy to
+/// implement recursively.
+///
+bool isSafeToDestroyConstant(const Constant *C);
+
+/// As we analyze each global, keep track of some information about it.  If we
+/// find out that the address of the global is taken, none of this info will be
+/// accurate.
+struct GlobalStatus {
+  /// True if the global's address is used in a comparison.
+  bool IsCompared = false;
+
+  /// True if the global is ever loaded.  If the global isn't ever loaded it
+  /// can be deleted.
+  bool IsLoaded = false;
+
+  /// Keep track of what stores to the global look like.
+  enum StoredType {
+    /// There is no store to this global.  It can thus be marked constant.
+    NotStored,
+
+    /// This global is stored to, but the only thing stored is the constant it
+    /// was initialized with. This is only tracked for scalar globals.
+    InitializerStored,
+
+    /// This global is stored to, but only its initializer and one other value
+    /// is ever stored to it.  If this global isStoredOnce, we track the value
+    /// stored to it in StoredOnceValue below.  This is only tracked for scalar
+    /// globals.
+    StoredOnce,
+
+    /// This global is stored to by multiple values or something else that we
+    /// cannot track.
+    Stored
+  } StoredType = NotStored;
+
+  /// If only one value (besides the initializer constant) is ever stored to
+  /// this global, keep track of what value it is.
+  Value *StoredOnceValue = nullptr;
+
+  /// These start out null/false.  When the first accessing function is noticed,
+  /// it is recorded. When a second different accessing function is noticed,
+  /// HasMultipleAccessingFunctions is set to true.
+  const Function *AccessingFunction = nullptr;
+  bool HasMultipleAccessingFunctions = false;
+
+  /// Set to true if this global has a user that is not an instruction (e.g. a
+  /// constant expr or GV initializer).
+  bool HasNonInstructionUser = false;
+
+  /// Set to the strongest atomic ordering requirement.
+  AtomicOrdering Ordering = AtomicOrdering::NotAtomic;
+
+  GlobalStatus();
+
+  /// Look at all uses of the global and fill in the GlobalStatus structure.  If
+  /// the global has its address taken, return true to indicate we can't do
+  /// anything with it.
+  static bool analyzeGlobal(const Value *V, GlobalStatus &GS);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_GLOBALSTATUS_H