c2e62c7459
The 'metadata' delta pass will remove !dbg attachments from globals (which are DIGlobalVariableExpression nodes). The DIGlobalVariableExpressions don't get eliminated from the IR however if they are still referenced by the globals field in DICompileUnit. Teach the 'di-metadata' pass to try removing global variable operands from metadata tuples as well as DINodes.
103 lines
3.4 KiB
C++
103 lines
3.4 KiB
C++
//===- ReduceDIMetadata.cpp - Specialized Delta pass for DebugInfo --------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements two functions used by the Generic Delta Debugging
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// Algorithm, which are used to reduce DebugInfo metadata nodes.
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//
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//===----------------------------------------------------------------------===//
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#include "ReduceDIMetadata.h"
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#include "Delta.h"
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#include "llvm/ADT/Sequence.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/IR/DebugInfoMetadata.h"
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#include "llvm/IR/InstIterator.h"
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#include <tuple>
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#include <vector>
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using namespace llvm;
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using MDNodeList = SmallVector<MDNode *>;
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void identifyUninterestingMDNodes(Oracle &O, MDNodeList &MDs) {
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SetVector<std::tuple<MDNode *, size_t, MDNode *>> Tuples;
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std::vector<MDNode *> ToLook;
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SetVector<MDNode *> Visited;
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// Start by looking at the attachments we collected
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for (const auto &NMD : MDs)
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if (NMD)
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ToLook.push_back(NMD);
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while (!ToLook.empty()) {
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MDNode *MD = ToLook.back();
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ToLook.pop_back();
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if (Visited.count(MD))
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continue;
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// Determine if the current MDNode is DebugInfo
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if (DINode *DIM = dyn_cast_or_null<DINode>(MD)) {
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// Scan operands and record attached tuples
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for (size_t I = 0; I < DIM->getNumOperands(); ++I)
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if (MDTuple *MDT = dyn_cast_or_null<MDTuple>(DIM->getOperand(I)))
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if (!Visited.count(MDT) && MDT->getNumOperands())
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Tuples.insert({DIM, I, MDT});
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}
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// Add all of the operands of the current node to the loop's todo list.
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for (Metadata *Op : MD->operands())
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if (MDNode *OMD = dyn_cast_or_null<MDNode>(Op))
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ToLook.push_back(OMD);
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Visited.insert(MD);
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}
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for (auto &T : Tuples) {
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auto [DbgNode, OpIdx, Tup] = T;
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// Remove the operands of the tuple that are not in the desired chunks.
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SmallVector<Metadata *, 16> TN;
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for (size_t I = 0; I < Tup->getNumOperands(); ++I) {
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// Ignore any operands that are not DebugInfo metadata nodes.
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if (Metadata *Op = Tup->getOperand(I).get()) {
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if (isa<DINode>(Op) || isa<DIGlobalVariableExpression>(Op))
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// Don't add uninteresting operands to the tuple.
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if (!O.shouldKeep())
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continue;
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TN.push_back(Op);
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}
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}
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if (TN.size() != Tup->getNumOperands())
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DbgNode->replaceOperandWith(OpIdx, DbgNode->get(DbgNode->getContext(), TN));
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}
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}
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static void extractDIMetadataFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
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Module &Program = WorkItem.getModule();
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MDNodeList MDs;
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// Collect all !dbg metadata attachments.
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for (const auto &DC : Program.debug_compile_units())
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if (DC)
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MDs.push_back(DC);
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for (GlobalVariable &GV : Program.globals())
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GV.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
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for (Function &F : Program.functions()) {
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F.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
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for (Instruction &I : instructions(F))
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if (auto *DI = I.getMetadata(llvm::LLVMContext::MD_dbg))
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MDs.push_back(DI);
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}
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identifyUninterestingMDNodes(O, MDs);
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}
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void llvm::reduceDIMetadataDeltaPass(TestRunner &Test) {
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runDeltaPass(Test, extractDIMetadataFromModule, "Reducing DIMetadata");
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}
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