llvm-6502/lib/Bitcode/Writer/ValueEnumerator.h
Duncan P. N. Exon Smith dad20b2ae2 IR: Split Metadata from Value
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
2014-12-09 18:38:53 +00:00

191 lines
6.1 KiB
C++

//===-- Bitcode/Writer/ValueEnumerator.h - Number values --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This class gives values and types Unique ID's.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
#define LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/UniqueVector.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/UseListOrder.h"
#include <vector>
namespace llvm {
class Type;
class Value;
class Instruction;
class BasicBlock;
class Comdat;
class Function;
class Module;
class Metadata;
class LocalAsMetadata;
class MDNode;
class NamedMDNode;
class AttributeSet;
class ValueSymbolTable;
class MDSymbolTable;
class raw_ostream;
class ValueEnumerator {
public:
typedef std::vector<Type*> TypeList;
// For each value, we remember its Value* and occurrence frequency.
typedef std::vector<std::pair<const Value*, unsigned> > ValueList;
UseListOrderStack UseListOrders;
private:
typedef DenseMap<Type*, unsigned> TypeMapType;
TypeMapType TypeMap;
TypeList Types;
typedef DenseMap<const Value*, unsigned> ValueMapType;
ValueMapType ValueMap;
ValueList Values;
typedef UniqueVector<const Comdat *> ComdatSetType;
ComdatSetType Comdats;
std::vector<const Metadata *> MDs;
SmallVector<const LocalAsMetadata *, 8> FunctionLocalMDs;
typedef DenseMap<const Metadata *, unsigned> MetadataMapType;
MetadataMapType MDValueMap;
typedef DenseMap<AttributeSet, unsigned> AttributeGroupMapType;
AttributeGroupMapType AttributeGroupMap;
std::vector<AttributeSet> AttributeGroups;
typedef DenseMap<AttributeSet, unsigned> AttributeMapType;
AttributeMapType AttributeMap;
std::vector<AttributeSet> Attribute;
/// GlobalBasicBlockIDs - This map memoizes the basic block ID's referenced by
/// the "getGlobalBasicBlockID" method.
mutable DenseMap<const BasicBlock*, unsigned> GlobalBasicBlockIDs;
typedef DenseMap<const Instruction*, unsigned> InstructionMapType;
InstructionMapType InstructionMap;
unsigned InstructionCount;
/// BasicBlocks - This contains all the basic blocks for the currently
/// incorporated function. Their reverse mapping is stored in ValueMap.
std::vector<const BasicBlock*> BasicBlocks;
/// When a function is incorporated, this is the size of the Values list
/// before incorporation.
unsigned NumModuleValues;
/// When a function is incorporated, this is the size of the MDValues list
/// before incorporation.
unsigned NumModuleMDs;
unsigned FirstFuncConstantID;
unsigned FirstInstID;
ValueEnumerator(const ValueEnumerator &) LLVM_DELETED_FUNCTION;
void operator=(const ValueEnumerator &) LLVM_DELETED_FUNCTION;
public:
ValueEnumerator(const Module &M);
void dump() const;
void print(raw_ostream &OS, const ValueMapType &Map, const char *Name) const;
void print(raw_ostream &OS, const MetadataMapType &Map,
const char *Name) const;
unsigned getValueID(const Value *V) const;
unsigned getMetadataID(const Metadata *V) const;
unsigned getTypeID(Type *T) const {
TypeMapType::const_iterator I = TypeMap.find(T);
assert(I != TypeMap.end() && "Type not in ValueEnumerator!");
return I->second-1;
}
unsigned getInstructionID(const Instruction *I) const;
void setInstructionID(const Instruction *I);
unsigned getAttributeID(AttributeSet PAL) const {
if (PAL.isEmpty()) return 0; // Null maps to zero.
AttributeMapType::const_iterator I = AttributeMap.find(PAL);
assert(I != AttributeMap.end() && "Attribute not in ValueEnumerator!");
return I->second;
}
unsigned getAttributeGroupID(AttributeSet PAL) const {
if (PAL.isEmpty()) return 0; // Null maps to zero.
AttributeGroupMapType::const_iterator I = AttributeGroupMap.find(PAL);
assert(I != AttributeGroupMap.end() && "Attribute not in ValueEnumerator!");
return I->second;
}
/// getFunctionConstantRange - Return the range of values that corresponds to
/// function-local constants.
void getFunctionConstantRange(unsigned &Start, unsigned &End) const {
Start = FirstFuncConstantID;
End = FirstInstID;
}
const ValueList &getValues() const { return Values; }
const std::vector<const Metadata *> &getMDs() const { return MDs; }
const SmallVectorImpl<const LocalAsMetadata *> &getFunctionLocalMDs() const {
return FunctionLocalMDs;
}
const TypeList &getTypes() const { return Types; }
const std::vector<const BasicBlock*> &getBasicBlocks() const {
return BasicBlocks;
}
const std::vector<AttributeSet> &getAttributes() const {
return Attribute;
}
const std::vector<AttributeSet> &getAttributeGroups() const {
return AttributeGroups;
}
const ComdatSetType &getComdats() const { return Comdats; }
unsigned getComdatID(const Comdat *C) const;
/// getGlobalBasicBlockID - This returns the function-specific ID for the
/// specified basic block. This is relatively expensive information, so it
/// should only be used by rare constructs such as address-of-label.
unsigned getGlobalBasicBlockID(const BasicBlock *BB) const;
/// incorporateFunction/purgeFunction - If you'd like to deal with a function,
/// use these two methods to get its data into the ValueEnumerator!
///
void incorporateFunction(const Function &F);
void purgeFunction();
private:
void OptimizeConstants(unsigned CstStart, unsigned CstEnd);
void EnumerateMDNodeOperands(const MDNode *N);
void EnumerateMetadata(const Metadata *MD);
void EnumerateFunctionLocalMetadata(const LocalAsMetadata *Local);
void EnumerateNamedMDNode(const NamedMDNode *NMD);
void EnumerateValue(const Value *V);
void EnumerateType(Type *T);
void EnumerateOperandType(const Value *V);
void EnumerateAttributes(AttributeSet PAL);
void EnumerateValueSymbolTable(const ValueSymbolTable &ST);
void EnumerateNamedMetadata(const Module &M);
};
} // End llvm namespace
#endif