//===- LexicalScopes.cpp - Collecting lexical scope info --------*- 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
//
//===----------------------------------------------------------------------===//
//
// This file implements LexicalScopes analysis.
//
// This pass collects lexical scope information and maps machine instructions
// to respective lexical scopes.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_LEXICALSCOPES_H
#define LLVM_CODEGEN_LEXICALSCOPES_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include <cassert>
#include <unordered_map>
#include <utility>
namespace llvm {
class MachineBasicBlock;
class MachineFunction;
class MachineInstr;
class MDNode;
//===----------------------------------------------------------------------===//
/// InsnRange - This is used to track range of instructions with identical
/// lexical scope.
///
using InsnRange = std::pair<const MachineInstr *, const MachineInstr *>;
//===----------------------------------------------------------------------===//
/// LexicalScope - This class is used to track scope information.
///
class LexicalScope {
public:
LexicalScope(LexicalScope *P, const DILocalScope *D, const DILocation *I,
bool A)
: Parent(P), Desc(D), InlinedAtLocation(I), AbstractScope(A) {
assert(D);
assert(D->getSubprogram()->getUnit()->getEmissionKind() !=
DICompileUnit::NoDebug &&
"Don't build lexical scopes for non-debug locations");
assert(D->isResolved() && "Expected resolved node");
assert((!I || I->isResolved()) && "Expected resolved node");
if (Parent)
Parent->addChild(this);
}
// Accessors.
LexicalScope *getParent() const { return Parent; }
const MDNode *getDesc() const { return Desc; }
const DILocation *getInlinedAt() const { return InlinedAtLocation; }
const DILocalScope *getScopeNode() const { return Desc; }
bool isAbstractScope() const { return AbstractScope; }
SmallVectorImpl<LexicalScope *> &getChildren() { return Children; }
SmallVectorImpl<InsnRange> &getRanges() { return Ranges; }
/// addChild - Add a child scope.
void addChild(LexicalScope *S) { Children.push_back(S); }
/// openInsnRange - This scope covers instruction range starting from MI.
void openInsnRange(const MachineInstr *MI) {
if (!FirstInsn)
FirstInsn = MI;
if (Parent)
Parent->openInsnRange(MI);
}
/// extendInsnRange - Extend the current instruction range covered by
/// this scope.
void extendInsnRange(const MachineInstr *MI) {
assert(FirstInsn && "MI Range is not open!");
LastInsn = MI;
if (Parent)
Parent->extendInsnRange(MI);
}
/// closeInsnRange - Create a range based on FirstInsn and LastInsn collected
/// until now. This is used when a new scope is encountered while walking
/// machine instructions.
void closeInsnRange(LexicalScope *NewScope = nullptr) {
assert(LastInsn && "Last insn missing!");
Ranges.push_back(InsnRange(FirstInsn, LastInsn));
FirstInsn = nullptr;
LastInsn = nullptr;
// If Parent dominates NewScope then do not close Parent's instruction
// range.
if (Parent && (!NewScope || !Parent->dominates(NewScope)))
Parent->closeInsnRange(NewScope);
}
/// dominates - Return true if current scope dominates given lexical scope.
bool dominates(const LexicalScope *S) const {
if (S == this)
return true;
if (DFSIn < S->getDFSIn() && DFSOut > S->getDFSOut())
return true;
return false;
}
// Depth First Search support to walk and manipulate LexicalScope hierarchy.
unsigned getDFSOut() const { return DFSOut; }
void setDFSOut(unsigned O) { DFSOut = O; }
unsigned getDFSIn() const { return DFSIn; }
void setDFSIn(unsigned I) { DFSIn = I; }
/// dump - print lexical scope.
void dump(unsigned Indent = 0) const;
private:
LexicalScope *Parent; // Parent to this scope.
const DILocalScope *Desc; // Debug info descriptor.
const DILocation *InlinedAtLocation; // Location at which this
// scope is inlined.
bool AbstractScope; // Abstract Scope
SmallVector<LexicalScope *, 4> Children; // Scopes defined in scope.
// Contents not owned.
SmallVector<InsnRange, 4> Ranges;
const MachineInstr *LastInsn = nullptr; // Last instruction of this scope.
const MachineInstr *FirstInsn = nullptr; // First instruction of this scope.
unsigned DFSIn = 0; // In & Out Depth use to determine scope nesting.
unsigned DFSOut = 0;
};
//===----------------------------------------------------------------------===//
/// LexicalScopes - This class provides interface to collect and use lexical
/// scoping information from machine instruction.
///
class LexicalScopes {
public:
LexicalScopes() = default;
/// initialize - Scan machine function and constuct lexical scope nest, resets
/// the instance if necessary.
void initialize(const MachineFunction &);
/// releaseMemory - release memory.
void reset();
/// empty - Return true if there is any lexical scope information available.
bool empty() { return CurrentFnLexicalScope == nullptr; }
/// getCurrentFunctionScope - Return lexical scope for the current function.
LexicalScope *getCurrentFunctionScope() const {
return CurrentFnLexicalScope;
}
/// getMachineBasicBlocks - Populate given set using machine basic blocks
/// which have machine instructions that belong to lexical scope identified by
/// DebugLoc.
void getMachineBasicBlocks(const DILocation *DL,
SmallPtrSetImpl<const MachineBasicBlock *> &MBBs);
/// Return true if DebugLoc's lexical scope dominates at least one machine
/// instruction's lexical scope in a given machine basic block.
bool dominates(const DILocation *DL, MachineBasicBlock *MBB);
/// findLexicalScope - Find lexical scope, either regular or inlined, for the
/// given DebugLoc. Return NULL if not found.
LexicalScope *findLexicalScope(const DILocation *DL);
/// getAbstractScopesList - Return a reference to list of abstract scopes.
ArrayRef<LexicalScope *> getAbstractScopesList() const {
return AbstractScopesList;
}
/// findAbstractScope - Find an abstract scope or return null.
LexicalScope *findAbstractScope(const DILocalScope *N) {
auto I = AbstractScopeMap.find(N);
return I != AbstractScopeMap.end() ? &I->second : nullptr;
}
/// findInlinedScope - Find an inlined scope for the given scope/inlined-at.
LexicalScope *findInlinedScope(const DILocalScope *N, const DILocation *IA) {
auto I = InlinedLexicalScopeMap.find(std::make_pair(N, IA));
return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
}
/// findLexicalScope - Find regular lexical scope or return null.
LexicalScope *findLexicalScope(const DILocalScope *N) {
auto I = LexicalScopeMap.find(N);
return I != LexicalScopeMap.end() ? &I->second : nullptr;
}
/// getOrCreateAbstractScope - Find or create an abstract lexical scope.
LexicalScope *getOrCreateAbstractScope(const DILocalScope *Scope);
private:
/// getOrCreateLexicalScope - Find lexical scope for the given Scope/IA. If
/// not available then create new lexical scope.
LexicalScope *getOrCreateLexicalScope(const DILocalScope *Scope,
const DILocation *IA = nullptr);
LexicalScope *getOrCreateLexicalScope(const DILocation *DL) {
return DL ? getOrCreateLexicalScope(DL->getScope(), DL->getInlinedAt())
: nullptr;
}
/// getOrCreateRegularScope - Find or create a regular lexical scope.
LexicalScope *getOrCreateRegularScope(const DILocalScope *Scope);
/// getOrCreateInlinedScope - Find or create an inlined lexical scope.
LexicalScope *getOrCreateInlinedScope(const DILocalScope *Scope,
const DILocation *InlinedAt);
/// extractLexicalScopes - Extract instruction ranges for each lexical scopes
/// for the given machine function.
void extractLexicalScopes(SmallVectorImpl<InsnRange> &MIRanges,
DenseMap<const MachineInstr *, LexicalScope *> &M);
void constructScopeNest(LexicalScope *Scope);
void
assignInstructionRanges(SmallVectorImpl<InsnRange> &MIRanges,
DenseMap<const MachineInstr *, LexicalScope *> &M);
const MachineFunction *MF = nullptr;
/// LexicalScopeMap - Tracks the scopes in the current function.
// Use an unordered_map to ensure value pointer validity over insertion.
std::unordered_map<const DILocalScope *, LexicalScope> LexicalScopeMap;
/// InlinedLexicalScopeMap - Tracks inlined function scopes in current
/// function.
std::unordered_map<std::pair<const DILocalScope *, const DILocation *>,
LexicalScope,
pair_hash<const DILocalScope *, const DILocation *>>
InlinedLexicalScopeMap;
/// AbstractScopeMap - These scopes are not included LexicalScopeMap.
// Use an unordered_map to ensure value pointer validity over insertion.
std::unordered_map<const DILocalScope *, LexicalScope> AbstractScopeMap;
/// AbstractScopesList - Tracks abstract scopes constructed while processing
/// a function.
SmallVector<LexicalScope *, 4> AbstractScopesList;
/// CurrentFnLexicalScope - Top level scope for the current function.
///
LexicalScope *CurrentFnLexicalScope = nullptr;
/// Map a location to the set of basic blocks it dominates. This is a cache
/// for \ref LexicalScopes::getMachineBasicBlocks results.
using BlockSetT = SmallPtrSet<const MachineBasicBlock *, 4>;
DenseMap<const DILocation *, std::unique_ptr<BlockSetT>> DominatedBlocks;
};
} // end namespace llvm
#endif // LLVM_CODEGEN_LEXICALSCOPES_H