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///===- DroppedVariableStats.cpp ----------------------------------------===//
///
/// 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
///
///===---------------------------------------------------------------------===//
/// \file
/// Dropped Variable Statistics for Debug Information. Reports any number
/// of #dbg_value that get dropped due to an optimization pass.
///
///===---------------------------------------------------------------------===//
#include "llvm/IR/DroppedVariableStats.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
using namespace llvm;
DroppedVariableStats::DroppedVariableStats(bool DroppedVarStatsEnabled)
: DroppedVariableStatsEnabled(DroppedVarStatsEnabled) {
if (DroppedVarStatsEnabled)
llvm::outs() << "Pass Level, Pass Name, Num of Dropped Variables, Func or "
"Module Name\n";
}
void DroppedVariableStats::setup() {
DebugVariablesStack.push_back({DenseMap<const Function *, DebugVariables>()});
InlinedAts.push_back({DenseMap<StringRef, DenseMap<VarID, DILocation *>>()});
}
void DroppedVariableStats::cleanup() {
assert(!DebugVariablesStack.empty() &&
"DebugVariablesStack shouldn't be empty!");
assert(!InlinedAts.empty() && "InlinedAts shouldn't be empty!");
DebugVariablesStack.pop_back();
InlinedAts.pop_back();
}
void DroppedVariableStats::calculateDroppedStatsAndPrint(
DebugVariables &DbgVariables, StringRef FuncName, StringRef PassID,
StringRef FuncOrModName, StringRef PassLevel, const Function *Func) {
unsigned DroppedCount = 0;
DenseSet<VarID> &DebugVariablesBeforeSet = DbgVariables.DebugVariablesBefore;
DenseSet<VarID> &DebugVariablesAfterSet = DbgVariables.DebugVariablesAfter;
auto It = InlinedAts.back().find(FuncName);
if (It == InlinedAts.back().end())
return;
DenseMap<VarID, DILocation *> &InlinedAtsMap = It->second;
// Find an Instruction that shares the same scope as the dropped #dbg_value
// or has a scope that is the child of the scope of the #dbg_value, and has
// an inlinedAt equal to the inlinedAt of the #dbg_value or it's inlinedAt
// chain contains the inlinedAt of the #dbg_value, if such an Instruction is
// found, debug information is dropped.
for (VarID Var : DebugVariablesBeforeSet) {
if (DebugVariablesAfterSet.contains(Var))
continue;
visitEveryInstruction(DroppedCount, InlinedAtsMap, Var);
removeVarFromAllSets(Var, Func);
}
if (DroppedCount > 0) {
llvm::outs() << PassLevel << ", " << PassID << ", " << DroppedCount << ", "
<< FuncOrModName << "\n";
PassDroppedVariables = true;
} else
PassDroppedVariables = false;
}
bool DroppedVariableStats::updateDroppedCount(
DILocation *DbgLoc, const DIScope *Scope, const DIScope *DbgValScope,
DenseMap<VarID, DILocation *> &InlinedAtsMap, VarID Var,
unsigned &DroppedCount) {
// If the Scope is a child of, or equal to the DbgValScope and is inlined at
// the Var's InlinedAt location, return true to signify that the Var has
// been dropped.
if (isScopeChildOfOrEqualTo(Scope, DbgValScope))
if (isInlinedAtChildOfOrEqualTo(DbgLoc->getInlinedAt(),
InlinedAtsMap[Var])) {
// Found another instruction in the variable's scope, so there exists a
// break point at which the variable could be observed. Count it as
// dropped.
DroppedCount++;
return true;
}
return false;
}
void DroppedVariableStats::run(DebugVariables &DbgVariables, StringRef FuncName,
bool Before) {
auto &VarIDSet = (Before ? DbgVariables.DebugVariablesBefore
: DbgVariables.DebugVariablesAfter);
auto &InlinedAtsMap = InlinedAts.back();
if (Before)
InlinedAtsMap.try_emplace(FuncName, DenseMap<VarID, DILocation *>());
VarIDSet = DenseSet<VarID>();
visitEveryDebugRecord(VarIDSet, InlinedAtsMap, FuncName, Before);
}
void DroppedVariableStats::populateVarIDSetAndInlinedMap(
const DILocalVariable *DbgVar, DebugLoc DbgLoc, DenseSet<VarID> &VarIDSet,
DenseMap<StringRef, DenseMap<VarID, DILocation *>> &InlinedAtsMap,
StringRef FuncName, bool Before) {
VarID Key{DbgVar->getScope(), DbgLoc->getInlinedAtScope(), DbgVar};
VarIDSet.insert(Key);
if (Before)
InlinedAtsMap[FuncName].try_emplace(Key, DbgLoc.getInlinedAt());
}
void DroppedVariableStats::removeVarFromAllSets(VarID Var, const Function *F) {
// Do not remove Var from the last element, it will be popped from the
// stack.
for (auto &DebugVariablesMap : llvm::drop_end(DebugVariablesStack))
DebugVariablesMap[F].DebugVariablesBefore.erase(Var);
}
bool DroppedVariableStats::isScopeChildOfOrEqualTo(const DIScope *Scope,
const DIScope *DbgValScope) {
while (Scope != nullptr) {
if (VisitedScope.insert(Scope).second) {
if (Scope == DbgValScope) {
VisitedScope.clear();
return true;
}
Scope = Scope->getScope();
} else {
VisitedScope.clear();
return false;
}
}
return false;
}
bool DroppedVariableStats::isInlinedAtChildOfOrEqualTo(
const DILocation *InlinedAt, const DILocation *DbgValInlinedAt) {
if (DbgValInlinedAt == InlinedAt)
return true;
if (!DbgValInlinedAt)
return false;
auto *IA = InlinedAt;
while (IA) {
if (IA == DbgValInlinedAt)
return true;
IA = IA->getInlinedAt();
}
return false;
}
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