llvm-6502/include/llvm/IR/DebugLoc.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

112 lines
3.9 KiB
C++

//===- DebugLoc.h - Debug Location Information ------------------*- 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 a number of light weight data structures used
// to describe and track debug location information.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_IR_DEBUGLOC_H
#define LLVM_IR_DEBUGLOC_H
#include "llvm/Support/DataTypes.h"
#include "llvm/IR/TrackingMDRef.h"
namespace llvm {
class LLVMContext;
class raw_ostream;
class MDNode;
/// DebugLoc - Debug location id. This is carried by Instruction, SDNode,
/// and MachineInstr to compactly encode file/line/scope information for an
/// operation.
class DebugLoc {
TrackingMDNodeRef Loc;
public:
DebugLoc() {}
DebugLoc(DebugLoc &&X) : Loc(std::move(X.Loc)) {}
DebugLoc(const DebugLoc &X) : Loc(X.Loc) {}
DebugLoc &operator=(DebugLoc &&X) {
Loc = std::move(X.Loc);
return *this;
}
DebugLoc &operator=(const DebugLoc &X) {
Loc = X.Loc;
return *this;
}
/// \brief Check whether this has a trivial destructor.
bool hasTrivialDestructor() const { return Loc.hasTrivialDestructor(); }
/// get - Get a new DebugLoc that corresponds to the specified line/col
/// scope/inline location.
static DebugLoc get(unsigned Line, unsigned Col, MDNode *Scope,
MDNode *InlinedAt = nullptr);
/// getFromDILocation - Translate the DILocation quad into a DebugLoc.
static DebugLoc getFromDILocation(MDNode *N);
/// getFromDILexicalBlock - Translate the DILexicalBlock into a DebugLoc.
static DebugLoc getFromDILexicalBlock(MDNode *N);
/// isUnknown - Return true if this is an unknown location.
bool isUnknown() const { return !Loc; }
unsigned getLine() const;
unsigned getCol() const;
/// getScope - This returns the scope pointer for this DebugLoc, or null if
/// invalid.
MDNode *getScope() const;
MDNode *getScope(const LLVMContext &) const { return getScope(); }
/// getInlinedAt - This returns the InlinedAt pointer for this DebugLoc, or
/// null if invalid or not present.
MDNode *getInlinedAt() const;
MDNode *getInlinedAt(const LLVMContext &) const { return getInlinedAt(); }
/// getScopeAndInlinedAt - Return both the Scope and the InlinedAt values.
void getScopeAndInlinedAt(MDNode *&Scope, MDNode *&IA) const;
void getScopeAndInlinedAt(MDNode *&Scope, MDNode *&IA,
const LLVMContext &) const {
return getScopeAndInlinedAt(Scope, IA);
}
/// getScopeNode - Get MDNode for DebugLoc's scope, or null if invalid.
MDNode *getScopeNode() const;
MDNode *getScopeNode(const LLVMContext &) const { return getScopeNode(); }
// getFnDebugLoc - Walk up the scope chain of given debug loc and find line
// number info for the function.
DebugLoc getFnDebugLoc() const;
DebugLoc getFnDebugLoc(const LLVMContext &) const {
return getFnDebugLoc();
}
/// getAsMDNode - This method converts the compressed DebugLoc node into a
/// DILocation compatible MDNode.
MDNode *getAsMDNode() const;
MDNode *getAsMDNode(LLVMContext &) const { return getAsMDNode(); }
bool operator==(const DebugLoc &DL) const { return Loc == DL.Loc; }
bool operator!=(const DebugLoc &DL) const { return !(*this == DL); }
void dump() const;
void dump(const LLVMContext &) const { dump(); }
/// \brief prints source location /path/to/file.exe:line:col @[inlined at]
void print(raw_ostream &OS) const;
void print(const LLVMContext &, raw_ostream &OS) const { print(OS); }
};
} // end namespace llvm
#endif /* LLVM_SUPPORT_DEBUGLOC_H */