llvm-6502/lib/CodeGen/LexicalScopes.cpp
Duncan P. N. Exon Smith ca3b3d5e2c AsmPrinter: Stop creating DebugLocs
While looking at a heap profile of a clang LTO bootstrap with -g, I
noticed that 2.2% of memory in an `llvm-lto` of clang is from calling
`DebugLoc::get()` in `collectVariableInfo()` (accounting for ~40% of
memory used for `MDLocation`s).

I suspect this was introduced by r226736, whose goal was to prevent
uniquing of `DebugLoc`s (goal achieved, if so).

There's no reason we need a `DebugLoc` here at all -- it was just being
used for (in)convenient API -- so the fix is to pass the scope and
inlined-at directly to `LexicalScopes::findInlinedScope()`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229459 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-17 00:02:27 +00:00

347 lines
12 KiB
C++

//===- LexicalScopes.cpp - Collecting lexical scope info ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements LexicalScopes analysis.
//
// This pass collects lexical scope information and maps machine instructions
// to respective lexical scopes.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LexicalScopes.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/FormattedStream.h"
using namespace llvm;
#define DEBUG_TYPE "lexicalscopes"
/// reset - Reset the instance so that it's prepared for another function.
void LexicalScopes::reset() {
MF = nullptr;
CurrentFnLexicalScope = nullptr;
LexicalScopeMap.clear();
AbstractScopeMap.clear();
InlinedLexicalScopeMap.clear();
AbstractScopesList.clear();
}
/// initialize - Scan machine function and constuct lexical scope nest.
void LexicalScopes::initialize(const MachineFunction &Fn) {
reset();
MF = &Fn;
SmallVector<InsnRange, 4> MIRanges;
DenseMap<const MachineInstr *, LexicalScope *> MI2ScopeMap;
extractLexicalScopes(MIRanges, MI2ScopeMap);
if (CurrentFnLexicalScope) {
constructScopeNest(CurrentFnLexicalScope);
assignInstructionRanges(MIRanges, MI2ScopeMap);
}
}
/// extractLexicalScopes - Extract instruction ranges for each lexical scopes
/// for the given machine function.
void LexicalScopes::extractLexicalScopes(
SmallVectorImpl<InsnRange> &MIRanges,
DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
// Scan each instruction and create scopes. First build working set of scopes.
for (const auto &MBB : *MF) {
const MachineInstr *RangeBeginMI = nullptr;
const MachineInstr *PrevMI = nullptr;
DebugLoc PrevDL;
for (const auto &MInsn : MBB) {
// Check if instruction has valid location information.
const DebugLoc MIDL = MInsn.getDebugLoc();
if (MIDL.isUnknown()) {
PrevMI = &MInsn;
continue;
}
// If scope has not changed then skip this instruction.
if (MIDL == PrevDL) {
PrevMI = &MInsn;
continue;
}
// Ignore DBG_VALUE. It does not contribute to any instruction in output.
if (MInsn.isDebugValue())
continue;
if (RangeBeginMI) {
// If we have already seen a beginning of an instruction range and
// current instruction scope does not match scope of first instruction
// in this range then create a new instruction range.
InsnRange R(RangeBeginMI, PrevMI);
MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
MIRanges.push_back(R);
}
// This is a beginning of a new instruction range.
RangeBeginMI = &MInsn;
// Reset previous markers.
PrevMI = &MInsn;
PrevDL = MIDL;
}
// Create last instruction range.
if (RangeBeginMI && PrevMI && !PrevDL.isUnknown()) {
InsnRange R(RangeBeginMI, PrevMI);
MIRanges.push_back(R);
MI2ScopeMap[RangeBeginMI] = getOrCreateLexicalScope(PrevDL);
}
}
}
/// findLexicalScope - Find lexical scope, either regular or inlined, for the
/// given DebugLoc. Return NULL if not found.
LexicalScope *LexicalScopes::findLexicalScope(DebugLoc DL) {
MDNode *Scope = nullptr;
MDNode *IA = nullptr;
DL.getScopeAndInlinedAt(Scope, IA, MF->getFunction()->getContext());
if (!Scope)
return nullptr;
// The scope that we were created with could have an extra file - which
// isn't what we care about in this case.
DIDescriptor D = DIDescriptor(Scope);
if (D.isLexicalBlockFile())
Scope = DILexicalBlockFile(Scope).getScope();
if (IA) {
auto I = InlinedLexicalScopeMap.find(std::make_pair(Scope, IA));
return I != InlinedLexicalScopeMap.end() ? &I->second : nullptr;
}
return findLexicalScope(Scope);
}
/// getOrCreateLexicalScope - Find lexical scope for the given DebugLoc. If
/// not available then create new lexical scope.
LexicalScope *LexicalScopes::getOrCreateLexicalScope(DebugLoc DL) {
if (DL.isUnknown())
return nullptr;
MDNode *Scope = nullptr;
MDNode *InlinedAt = nullptr;
DL.getScopeAndInlinedAt(Scope, InlinedAt, MF->getFunction()->getContext());
if (InlinedAt) {
// Create an abstract scope for inlined function.
getOrCreateAbstractScope(Scope);
// Create an inlined scope for inlined function.
return getOrCreateInlinedScope(Scope, InlinedAt);
}
return getOrCreateRegularScope(Scope);
}
/// getOrCreateRegularScope - Find or create a regular lexical scope.
LexicalScope *LexicalScopes::getOrCreateRegularScope(MDNode *Scope) {
DIDescriptor D = DIDescriptor(Scope);
if (D.isLexicalBlockFile()) {
Scope = DILexicalBlockFile(Scope).getScope();
D = DIDescriptor(Scope);
}
auto I = LexicalScopeMap.find(Scope);
if (I != LexicalScopeMap.end())
return &I->second;
LexicalScope *Parent = nullptr;
if (D.isLexicalBlock())
Parent = getOrCreateLexicalScope(DebugLoc::getFromDILexicalBlock(Scope));
I = LexicalScopeMap.emplace(std::piecewise_construct,
std::forward_as_tuple(Scope),
std::forward_as_tuple(Parent, DIDescriptor(Scope),
nullptr, false)).first;
if (!Parent) {
assert(DIDescriptor(Scope).isSubprogram());
assert(DISubprogram(Scope).describes(MF->getFunction()));
assert(!CurrentFnLexicalScope);
CurrentFnLexicalScope = &I->second;
}
return &I->second;
}
/// getOrCreateInlinedScope - Find or create an inlined lexical scope.
LexicalScope *LexicalScopes::getOrCreateInlinedScope(MDNode *ScopeNode,
MDNode *InlinedAt) {
std::pair<const MDNode*, const MDNode*> P(ScopeNode, InlinedAt);
auto I = InlinedLexicalScopeMap.find(P);
if (I != InlinedLexicalScopeMap.end())
return &I->second;
LexicalScope *Parent;
DILexicalBlock Scope(ScopeNode);
if (Scope.isSubprogram())
Parent = getOrCreateLexicalScope(DebugLoc::getFromDILocation(InlinedAt));
else
Parent = getOrCreateInlinedScope(Scope.getContext(), InlinedAt);
I = InlinedLexicalScopeMap.emplace(std::piecewise_construct,
std::forward_as_tuple(P),
std::forward_as_tuple(Parent, Scope,
InlinedAt, false))
.first;
return &I->second;
}
/// getOrCreateAbstractScope - Find or create an abstract lexical scope.
LexicalScope *LexicalScopes::getOrCreateAbstractScope(const MDNode *N) {
assert(N && "Invalid Scope encoding!");
DIDescriptor Scope(N);
if (Scope.isLexicalBlockFile())
Scope = DILexicalBlockFile(Scope).getScope();
auto I = AbstractScopeMap.find(Scope);
if (I != AbstractScopeMap.end())
return &I->second;
LexicalScope *Parent = nullptr;
if (Scope.isLexicalBlock()) {
DILexicalBlock DB(Scope);
DIDescriptor ParentDesc = DB.getContext();
Parent = getOrCreateAbstractScope(ParentDesc);
}
I = AbstractScopeMap.emplace(std::piecewise_construct,
std::forward_as_tuple(Scope),
std::forward_as_tuple(Parent, Scope,
nullptr, true)).first;
if (Scope.isSubprogram())
AbstractScopesList.push_back(&I->second);
return &I->second;
}
/// constructScopeNest
void LexicalScopes::constructScopeNest(LexicalScope *Scope) {
assert(Scope && "Unable to calculate scope dominance graph!");
SmallVector<LexicalScope *, 4> WorkStack;
WorkStack.push_back(Scope);
unsigned Counter = 0;
while (!WorkStack.empty()) {
LexicalScope *WS = WorkStack.back();
const SmallVectorImpl<LexicalScope *> &Children = WS->getChildren();
bool visitedChildren = false;
for (SmallVectorImpl<LexicalScope *>::const_iterator SI = Children.begin(),
SE = Children.end();
SI != SE; ++SI) {
LexicalScope *ChildScope = *SI;
if (!ChildScope->getDFSOut()) {
WorkStack.push_back(ChildScope);
visitedChildren = true;
ChildScope->setDFSIn(++Counter);
break;
}
}
if (!visitedChildren) {
WorkStack.pop_back();
WS->setDFSOut(++Counter);
}
}
}
/// assignInstructionRanges - Find ranges of instructions covered by each
/// lexical scope.
void LexicalScopes::assignInstructionRanges(
SmallVectorImpl<InsnRange> &MIRanges,
DenseMap<const MachineInstr *, LexicalScope *> &MI2ScopeMap) {
LexicalScope *PrevLexicalScope = nullptr;
for (SmallVectorImpl<InsnRange>::const_iterator RI = MIRanges.begin(),
RE = MIRanges.end();
RI != RE; ++RI) {
const InsnRange &R = *RI;
LexicalScope *S = MI2ScopeMap.lookup(R.first);
assert(S && "Lost LexicalScope for a machine instruction!");
if (PrevLexicalScope && !PrevLexicalScope->dominates(S))
PrevLexicalScope->closeInsnRange(S);
S->openInsnRange(R.first);
S->extendInsnRange(R.second);
PrevLexicalScope = S;
}
if (PrevLexicalScope)
PrevLexicalScope->closeInsnRange();
}
/// getMachineBasicBlocks - Populate given set using machine basic blocks which
/// have machine instructions that belong to lexical scope identified by
/// DebugLoc.
void LexicalScopes::getMachineBasicBlocks(
DebugLoc DL, SmallPtrSetImpl<const MachineBasicBlock *> &MBBs) {
MBBs.clear();
LexicalScope *Scope = getOrCreateLexicalScope(DL);
if (!Scope)
return;
if (Scope == CurrentFnLexicalScope) {
for (const auto &MBB : *MF)
MBBs.insert(&MBB);
return;
}
SmallVectorImpl<InsnRange> &InsnRanges = Scope->getRanges();
for (SmallVectorImpl<InsnRange>::iterator I = InsnRanges.begin(),
E = InsnRanges.end();
I != E; ++I) {
InsnRange &R = *I;
MBBs.insert(R.first->getParent());
}
}
/// dominates - Return true if DebugLoc's lexical scope dominates at least one
/// machine instruction's lexical scope in a given machine basic block.
bool LexicalScopes::dominates(DebugLoc DL, MachineBasicBlock *MBB) {
LexicalScope *Scope = getOrCreateLexicalScope(DL);
if (!Scope)
return false;
// Current function scope covers all basic blocks in the function.
if (Scope == CurrentFnLexicalScope && MBB->getParent() == MF)
return true;
bool Result = false;
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
++I) {
DebugLoc IDL = I->getDebugLoc();
if (IDL.isUnknown())
continue;
if (LexicalScope *IScope = getOrCreateLexicalScope(IDL))
if (Scope->dominates(IScope))
return true;
}
return Result;
}
/// dump - Print data structures.
void LexicalScope::dump(unsigned Indent) const {
#ifndef NDEBUG
raw_ostream &err = dbgs();
err.indent(Indent);
err << "DFSIn: " << DFSIn << " DFSOut: " << DFSOut << "\n";
const MDNode *N = Desc;
err.indent(Indent);
N->dump();
if (AbstractScope)
err << std::string(Indent, ' ') << "Abstract Scope\n";
if (!Children.empty())
err << std::string(Indent + 2, ' ') << "Children ...\n";
for (unsigned i = 0, e = Children.size(); i != e; ++i)
if (Children[i] != this)
Children[i]->dump(Indent + 2);
#endif
}