Add the MDBuilder helper class for conveniently creating metadata.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154766 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 101 insertions, 0 deletions

diff --git a/include/llvm/Support/MDBuilder.h b/include/llvm/Support/MDBuilder.h
new file mode 100644
index 0000000..20f5d70
--- /dev/null
+++ b/include/llvm/Support/MDBuilder.h
@@ -0,0 +1,101 @@
+//===---- llvm/Support/MDBuilder.h - Builder for LLVM metadata --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the MDBuilder class, which is used as a convenient way to
+// create LLVM metadata with a consistent and simplified interface.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_MDBUILDER_H
+#define LLVM_SUPPORT_MDBUILDER_H
+
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Metadata.h"
+#include "llvm/ADT/APInt.h"
+
+namespace llvm {
+
+  class MDBuilder {
+    LLVMContext &Context;
+
+  public:
+    MDBuilder(LLVMContext &context) : Context(context) {}
+
+    /// CreateString - Return the given string as metadata.
+    MDString *CreateString(StringRef Str) const {
+      return MDString::get(Context, Str);
+    }
+
+    //===------------------------------------------------------------------===//
+    // Range metadata.
+    //===------------------------------------------------------------------===//
+
+    /// CreateRange - Return metadata describing the range [Lo, Hi).
+    MDNode *CreateRange(const APInt &Lo, const APInt &Hi) const {
+      assert(Lo.getBitWidth() == Hi.getBitWidth() && "Mismatched bitwidths!");
+      // If the range is everything then it is useless.
+      if (Hi == Lo)
+        return 0;
+
+      // Return the range [Lo, Hi).
+      Type *Ty = IntegerType::get(Context, Lo.getBitWidth());
+      Value *Range[2] = { ConstantInt::get(Ty, Lo), ConstantInt::get(Ty, Hi) };
+      return MDNode::get(Context, Range);
+    }
+
+
+    //===------------------------------------------------------------------===//
+    // TBAA metadata.
+    //===------------------------------------------------------------------===//
+
+    /// CreateAnonymousTBAARoot - Return metadata appropriate for a TBAA root
+    /// node.  Each returned node is distinct from all other metadata and will
+    /// never be identified (uniqued) with anything else.
+    MDNode *CreateAnonymousTBAARoot() const {
+      // To ensure uniqueness the root node is self-referential.
+      MDNode *Dummy = MDNode::getTemporary(Context, ArrayRef<Value*>());
+      MDNode *Root = MDNode::get(Context, Dummy);
+      // At this point we have
+      //   !0 = metadata !{}            <- dummy
+      //   !1 = metadata !{metadata !0} <- root
+      // Replace the dummy operand with the root node itself and delete the dummy.
+      Root->replaceOperandWith(0, Root);
+      MDNode::deleteTemporary(Dummy);
+      // We now have
+      //   !1 = metadata !{metadata !1} <- self-referential root
+      return Root;
+    }
+
+    /// CreateTBAARoot - Return metadata appropriate for a TBAA root node with
+    /// the given name.  This may be identified (uniqued) with other roots with
+    /// the same name.
+    MDNode *CreateTBAARoot(StringRef Name) const {
+      return MDNode::get(Context, CreateString(Name));
+    }
+
+    /// CreateTBAANode - Return metadata for a non-root TBAA node with the given
+    /// name, parent in the TBAA tree, and value for 'pointsToConstantMemory'.
+    MDNode *CreateTBAANode(StringRef Name, MDNode *Parent,
+                           bool isConstant = false) const {
+      if (isConstant) {
+        Constant *Flags = ConstantInt::get(Type::getInt64Ty(Context), 1);
+        Value *Ops[3] = { CreateString(Name), Parent, Flags };
+        return MDNode::get(Context, Ops);
+      } else {
+        Value *Ops[2] = { CreateString(Name), Parent };
+        return MDNode::get(Context, Ops);
+      }
+    }
+  };
+
+} // end namespace llvm
+
+#endif