[llvm] [llvm-dwarfdump][LineCov 1/3] Add variable coverage metrics (PR #169646)

[Stephen Tozer via llvm-commits]

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@@ -0,0 +1,244 @@
+//===-- Coverage.cpp - Debug info coverage metrics ------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm-dwarfdump.h"
+#include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/DebugInfo/DIContext.h"
+#include "llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h"
+#include "llvm/DebugInfo/DWARF/DWARFCompileUnit.h"
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/DebugProgramInstruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IRReader/IRReader.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
+#include <set>
+
+using namespace llvm;
+using namespace llvm::dwarf;
+using namespace llvm::object;
+
+typedef std::pair<std::string, std::string> StringPair;
+
+static std::optional<std::set<std::pair<uint16_t, uint32_t>>>
+computeVariableCoverage(DWARFContext &DICtx, DWARFDie DIE,
+                        const DWARFDebugLine::LineTable *const LineTable) {
+  auto addLines = [](const DWARFDebugLine::LineTable *LineTable,
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SLTozer wrote:

I think the function and the lambda could do with commenting (a few sentences) to explain what they're doing; it might also help if `DIE` was renamed `VariableDIE`, to make it clear that this is the variable that coverage is being computed for, and also to explain with either a comment or a typedef that the returned set contains `{FileIndex, Line}` pairings (representing unique source locations).

https://github.com/llvm/llvm-project/pull/169646