[llvm] [Analysis] Add DebugInfoCache analysis (PR #118629)

[Felipe de Azevedo Piovezan via llvm-commits]

================
@@ -0,0 +1,211 @@
+//===- DebugInfoCacheTest.cpp - DebugInfoCache unit tests -----------------===//
+//
+// 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/Analysis/DebugInfoCache.h"
+#include "llvm/AsmParser/Parser.h"
+#include "llvm/IR/Module.h"
+#include "llvm/IR/Verifier.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/raw_ostream.h"
+#include "gtest/gtest.h"
+
+namespace llvm {
+namespace {
+
+// Forward declare the assembly
+extern StringRef MultiCUModule;
+
+const DICompileUnit *findCU(const Module &M, StringRef FileName) {
+  for (const auto CU : M.debug_compile_units()) {
+    if (CU->getFilename() == FileName)
+      return CU;
+  }
+
+  return nullptr;
+}
+
+class DebugInfoCacheTest : public testing::Test {
+protected:
+  LLVMContext C;
+
+  std::unique_ptr<Module> makeModule(StringRef Assembly) {
+    SMDiagnostic Err;
+    auto M = parseAssemblyString(Assembly, Err, C);
+    if (!M)
+      Err.print("DebugInfoCacheTest", errs());
+
+    verifyModule(*M, &errs());
+    return M;
+  }
+};
+
+TEST_F(DebugInfoCacheTest, TestEmpty) {
+  auto M = makeModule("");
+  DebugInfoCache DIC{*M};
+  EXPECT_EQ(DIC.Result.size(), 0u);
+}
+
+TEST_F(DebugInfoCacheTest, TestMultiCU) {
+  auto M = makeModule(MultiCUModule);
+  DebugInfoCache DIC{*M};
+  EXPECT_EQ(DIC.Result.size(), 2u);
+
+  auto *File1CU = findCU(*M, "file1.cpp");
+  EXPECT_NE(File1CU, nullptr);
+
+  auto File1DIFinder = DIC.Result.find(File1CU);
+  EXPECT_NE(File1DIFinder, DIC.Result.end());
+
+  EXPECT_EQ(File1DIFinder->getSecond().compile_unit_count(), 1u);
+  EXPECT_EQ(File1DIFinder->getSecond().type_count(), 6u);
+  EXPECT_EQ(File1DIFinder->getSecond().subprogram_count(), 0u);
+  EXPECT_EQ(File1DIFinder->getSecond().scope_count(), 1u);
----------------
felipepiovezan wrote:

This is testing `DebugInfoFinder` more than it is testing the analysis. The question we want to answer is "is this analysis doing the same as if we instantiated a DebugInfoFinder on this CU?" The assertions above (and below) don't quite answer that question, or they do it in a very indirect way.

IMO you could just:

```
DebugInfoFinder ExpectedDIFinder1;
ExpectedDIFinder.processCompileUnit(File1CU);

DebugInfoFinder DIFinder1 = File1DIFinder->getSecond()

EXPECT_TRUE(equal_range(DIFinder1.compile_units(), ExpectedDIFinder1.compile_units()));
EXPECT_TRUE(...)
```

https://github.com/llvm/llvm-project/pull/118629