[llvm] [StableHash] Implement stable global name for the hash computation (PR #106156)

[Ellis Hoag via llvm-commits]

================
@@ -0,0 +1,143 @@
+//===- MachineStableHashTest.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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineStableHash.h"
+#include "llvm/CodeGen/MIRParser/MIRParser.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/FileCheck/FileCheck.h"
+#include "llvm/IR/Module.h"
+#include "llvm/MC/TargetRegistry.h"
+#include "llvm/Support/SourceMgr.h"
+#include "llvm/Support/TargetSelect.h"
+#include "llvm/Target/TargetMachine.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+class MachineStableHashTest : public testing::Test {
+public:
+  MachineStableHashTest() {}
+
+protected:
+  LLVMContext Context;
+  std::unique_ptr<Module> M;
+  std::unique_ptr<MIRParser> MIR;
+
+  static void SetUpTestCase() {
+    InitializeAllTargetInfos();
+    InitializeAllTargets();
+    InitializeAllTargetMCs();
+  }
+
+  void SetUp() override { M = std::make_unique<Module>("Dummy", Context); }
+
+  std::unique_ptr<LLVMTargetMachine>
+  createTargetMachine(std::string TT, StringRef CPU, StringRef FS) {
+    std::string Error;
+    const Target *T = TargetRegistry::lookupTarget(TT, Error);
+    if (!T)
+      return nullptr;
+    TargetOptions Options;
+    return std::unique_ptr<LLVMTargetMachine>(
+        static_cast<LLVMTargetMachine *>(T->createTargetMachine(
+            TT, CPU, FS, Options, std::nullopt, std::nullopt)));
+  }
+
+  std::unique_ptr<Module> parseMIR(const TargetMachine &TM, StringRef MIRCode,
+                                   MachineModuleInfo &MMI) {
+    SMDiagnostic Diagnostic;
+    std::unique_ptr<MemoryBuffer> MBuffer = MemoryBuffer::getMemBuffer(MIRCode);
+    MIR = createMIRParser(std::move(MBuffer), Context);
+    if (!MIR)
+      return nullptr;
+
+    std::unique_ptr<Module> Mod = MIR->parseIRModule();
+    if (!Mod)
+      return nullptr;
+
+    Mod->setDataLayout(TM.createDataLayout());
+
+    if (MIR->parseMachineFunctions(*Mod, MMI)) {
+      M.reset();
+      return nullptr;
+    }
+
+    return Mod;
+  }
+};
+
+TEST_F(MachineStableHashTest, StableGlobalName) {
+  auto TM = createTargetMachine(("aarch64--"), "", "");
+  if (!TM)
+    GTEST_SKIP();
+  StringRef MIRString = R"MIR(
+--- |
+  define void @f1() { ret void }
+  define void @f2() { ret void }
+  define void @f3() { ret void }
+  define void @f4() { ret void }
+  declare void @goo()
+  declare void @goo.llvm.123()
+  declare void @goo.__uniq.456()
+  declare void @goo.invalid.789()
+...
+---
+name:            f1
+alignment:       16
+tracksRegLiveness: true
+frameInfo:
+  maxAlignment:    16
+machineFunctionInfo: {}
+body:             |
+  bb.0:
+  liveins: $lr
+    BL @goo
+  RET undef $lr
+
+...
+---
+name:            f2
+body:             |
+  bb.0:
+  liveins: $lr
+    BL @goo.llvm.123
+  RET undef $lr
+...
+---
+name:            f3
+body:             |
+  bb.0:
+  liveins: $lr
+    BL @goo.__uniq.456
+  RET undef $lr
+...
+---
+name:            f4
+body:             |
+  bb.0:
+  liveins: $lr
+    BL @goo.invalid.789
+  RET undef $lr
+...
+)MIR";
+  MachineModuleInfo MMI(TM.get());
+  M = parseMIR(*TM, MIRString, MMI);
+  ASSERT_TRUE(M);
+  auto *MF1 = MMI.getMachineFunction(*M->getFunction("f1"));
+  auto *MF2 = MMI.getMachineFunction(*M->getFunction("f2"));
+  auto *MF3 = MMI.getMachineFunction(*M->getFunction("f3"));
+  auto *MF4 = MMI.getMachineFunction(*M->getFunction("f4"));
+
+  // Expect the suffix, `.llvm.{number}` to be ignored.
+  EXPECT_EQ(stableHashValue(*MF1), stableHashValue(*MF2));
----------------
ellishg wrote:

```suggestion
  EXPECT_EQ(stableHashValue(*MF1), stableHashValue(*MF2)) << "Expect the suffix, `.llvm.{number}` to be ignored.";
```
It would be nice to have the explanation in the error message if the test breaks.

https://github.com/llvm/llvm-project/pull/106156