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Split `Metadata` away from the `Value` class hierarchy, as part of PR21532. Assembly and bitcode changes are in the wings, but this is the bulk of the change for the IR C++ API. I have a follow-up patch prepared for `clang`. If this breaks other sub-projects, I apologize in advance :(. Help me compile it on Darwin I'll try to fix it. FWIW, the errors should be easy to fix, so it may be simpler to just fix it yourself. This breaks the build for all metadata-related code that's out-of-tree. Rest assured the transition is mechanical and the compiler should catch almost all of the problems. Here's a quick guide for updating your code: - `Metadata` is the root of a class hierarchy with three main classes: `MDNode`, `MDString`, and `ValueAsMetadata`. It is distinct from the `Value` class hierarchy. It is typeless -- i.e., instances do *not* have a `Type`. - `MDNode`'s operands are all `Metadata *` (instead of `Value *`). - `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively. If you're referring solely to resolved `MDNode`s -- post graph construction -- just use `MDNode*`. - `MDNode` (and the rest of `Metadata`) have only limited support for `replaceAllUsesWith()`. As long as an `MDNode` is pointing at a forward declaration -- the result of `MDNode::getTemporary()` -- it maintains a side map of its uses and can RAUW itself. Once the forward declarations are fully resolved RAUW support is dropped on the ground. This means that uniquing collisions on changing operands cause nodes to become "distinct". (This already happened fairly commonly, whenever an operand went to null.) If you're constructing complex (non self-reference) `MDNode` cycles, you need to call `MDNode::resolveCycles()` on each node (or on a top-level node that somehow references all of the nodes). Also, don't do that. Metadata cycles (and the RAUW machinery needed to construct them) are expensive. - An `MDNode` can only refer to a `Constant` through a bridge called `ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`). As a side effect, accessing an operand of an `MDNode` that is known to be, e.g., `ConstantInt`, takes three steps: first, cast from `Metadata` to `ConstantAsMetadata`; second, extract the `Constant`; third, cast down to `ConstantInt`. The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have metadata schema owners transition away from using `Constant`s when the type isn't important (and they don't care about referring to `GlobalValue`s). In the meantime, I've added transitional API to the `mdconst` namespace that matches semantics with the old code, in order to avoid adding the error-prone three-step equivalent to every call site. If your old code was: MDNode *N = foo(); bar(isa <ConstantInt>(N->getOperand(0))); baz(cast <ConstantInt>(N->getOperand(1))); bak(cast_or_null <ConstantInt>(N->getOperand(2))); bat(dyn_cast <ConstantInt>(N->getOperand(3))); bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4))); you can trivially match its semantics with: MDNode *N = foo(); bar(mdconst::hasa <ConstantInt>(N->getOperand(0))); baz(mdconst::extract <ConstantInt>(N->getOperand(1))); bak(mdconst::extract_or_null <ConstantInt>(N->getOperand(2))); bat(mdconst::dyn_extract <ConstantInt>(N->getOperand(3))); bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4))); and when you transition your metadata schema to `MDInt`: MDNode *N = foo(); bar(isa <MDInt>(N->getOperand(0))); baz(cast <MDInt>(N->getOperand(1))); bak(cast_or_null <MDInt>(N->getOperand(2))); bat(dyn_cast <MDInt>(N->getOperand(3))); bay(dyn_cast_or_null<MDInt>(N->getOperand(4))); - A `CallInst` -- specifically, intrinsic instructions -- can refer to metadata through a bridge called `MetadataAsValue`. This is a subclass of `Value` where `getType()->isMetadataTy()`. `MetadataAsValue` is the *only* class that can legally refer to a `LocalAsMetadata`, which is a bridged form of non-`Constant` values like `Argument` and `Instruction`. It can also refer to any other `Metadata` subclass. (I'll break all your testcases in a follow-up commit, when I propagate this change to assembly.) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223802 91177308-0d34-0410-b5e6-96231b3b80d8
156 lines
5.8 KiB
C++
156 lines
5.8 KiB
C++
//===---- llvm/MDBuilder.h - Builder for LLVM metadata ----------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the MDBuilder class, which is used as a convenient way to
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// create LLVM metadata with a consistent and simplified interface.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_MDBUILDER_H
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#define LLVM_IR_MDBUILDER_H
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/DataTypes.h"
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#include <utility>
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namespace llvm {
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class APInt;
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template <typename T> class ArrayRef;
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class LLVMContext;
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class Constant;
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class ConstantAsMetadata;
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class MDNode;
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class MDString;
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class MDBuilder {
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LLVMContext &Context;
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public:
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MDBuilder(LLVMContext &context) : Context(context) {}
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/// \brief Return the given string as metadata.
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MDString *createString(StringRef Str);
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/// \brief Return the given constant as metadata.
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ConstantAsMetadata *createConstant(Constant *C);
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//===------------------------------------------------------------------===//
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// FPMath metadata.
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//===------------------------------------------------------------------===//
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/// \brief Return metadata with the given settings. The special value 0.0
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/// for the Accuracy parameter indicates the default (maximal precision)
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/// setting.
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MDNode *createFPMath(float Accuracy);
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//===------------------------------------------------------------------===//
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// Prof metadata.
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//===------------------------------------------------------------------===//
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/// \brief Return metadata containing two branch weights.
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MDNode *createBranchWeights(uint32_t TrueWeight, uint32_t FalseWeight);
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/// \brief Return metadata containing a number of branch weights.
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MDNode *createBranchWeights(ArrayRef<uint32_t> Weights);
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//===------------------------------------------------------------------===//
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// Range metadata.
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//===------------------------------------------------------------------===//
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/// \brief Return metadata describing the range [Lo, Hi).
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MDNode *createRange(const APInt &Lo, const APInt &Hi);
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//===------------------------------------------------------------------===//
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// AA metadata.
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//===------------------------------------------------------------------===//
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protected:
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/// \brief Return metadata appropriate for a AA root node (scope or TBAA).
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/// Each returned node is distinct from all other metadata and will never
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/// be identified (uniqued) with anything else.
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MDNode *createAnonymousAARoot(StringRef Name = StringRef(),
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MDNode *Extra = nullptr);
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public:
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/// \brief Return metadata appropriate for a TBAA root node. Each returned
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/// node is distinct from all other metadata and will never be identified
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/// (uniqued) with anything else.
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MDNode *createAnonymousTBAARoot() {
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return createAnonymousAARoot();
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}
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/// \brief Return metadata appropriate for an alias scope domain node.
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/// Each returned node is distinct from all other metadata and will never
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/// be identified (uniqued) with anything else.
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MDNode *createAnonymousAliasScopeDomain(StringRef Name = StringRef()) {
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return createAnonymousAARoot(Name);
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}
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/// \brief Return metadata appropriate for an alias scope root node.
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/// Each returned node is distinct from all other metadata and will never
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/// be identified (uniqued) with anything else.
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MDNode *createAnonymousAliasScope(MDNode *Domain,
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StringRef Name = StringRef()) {
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return createAnonymousAARoot(Name, Domain);
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}
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/// \brief Return metadata appropriate for a TBAA root node with the given
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/// name. This may be identified (uniqued) with other roots with the same
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/// name.
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MDNode *createTBAARoot(StringRef Name);
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/// \brief Return metadata appropriate for an alias scope domain node with
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/// the given name. This may be identified (uniqued) with other roots with
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/// the same name.
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MDNode *createAliasScopeDomain(StringRef Name);
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/// \brief Return metadata appropriate for an alias scope node with
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/// the given name. This may be identified (uniqued) with other scopes with
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/// the same name and domain.
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MDNode *createAliasScope(StringRef Name, MDNode *Domain);
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/// \brief Return metadata for a non-root TBAA node with the given name,
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/// parent in the TBAA tree, and value for 'pointsToConstantMemory'.
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MDNode *createTBAANode(StringRef Name, MDNode *Parent,
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bool isConstant = false);
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struct TBAAStructField {
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uint64_t Offset;
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uint64_t Size;
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MDNode *TBAA;
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TBAAStructField(uint64_t Offset, uint64_t Size, MDNode *TBAA) :
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Offset(Offset), Size(Size), TBAA(TBAA) {}
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};
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/// \brief Return metadata for a tbaa.struct node with the given
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/// struct field descriptions.
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MDNode *createTBAAStructNode(ArrayRef<TBAAStructField> Fields);
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/// \brief Return metadata for a TBAA struct node in the type DAG
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/// with the given name, a list of pairs (offset, field type in the type DAG).
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MDNode *
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createTBAAStructTypeNode(StringRef Name,
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ArrayRef<std::pair<MDNode *, uint64_t>> Fields);
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/// \brief Return metadata for a TBAA scalar type node with the
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/// given name, an offset and a parent in the TBAA type DAG.
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MDNode *createTBAAScalarTypeNode(StringRef Name, MDNode *Parent,
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uint64_t Offset = 0);
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/// \brief Return metadata for a TBAA tag node with the given
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/// base type, access type and offset relative to the base type.
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MDNode *createTBAAStructTagNode(MDNode *BaseType, MDNode *AccessType,
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uint64_t Offset);
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};
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} // end namespace llvm
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#endif
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