[llvm] [JITLink][AArch32] Unittest for error paths of readAddend functionality (PR #69636)

[Stefan Gränitz via llvm-commits]

================
@@ -67,6 +68,99 @@ TEST(AArch32_ELF, EdgeKinds) {
   }
 }
 
+struct ThumbRelocation {
+  /// Create a read-only reference to a Thumb32 fixup.
+  ThumbRelocation(const char *FixupPtr)
+      : Hi{*reinterpret_cast<const support::ulittle16_t *>(FixupPtr)},
+        Lo{*reinterpret_cast<const support::ulittle16_t *>(FixupPtr + 2)} {}
+
+  const support::ulittle16_t &Hi; // First halfword
+  const support::ulittle16_t &Lo; // Second halfword
+};
+
+struct ArmRelocation {
+
+  ArmRelocation(const char *FixupPtr)
+      : Wd{*reinterpret_cast<const support::ulittle32_t *>(FixupPtr)} {}
+
+  const support::ulittle32_t &Wd;
+};
+
+std::string makeUnexpectedOpcodeError(const LinkGraph &G,
+                                      const ThumbRelocation &R,
+                                      Edge::Kind Kind) {
+  return formatv("Invalid opcode [ {0:x4}, {1:x4} ] for relocation: {2}",
+                 static_cast<uint16_t>(R.Hi), static_cast<uint16_t>(R.Lo),
+                 G.getEdgeKindName(Kind));
+}
+
+std::string makeUnexpectedOpcodeError(const LinkGraph &G,
+                                      const ArmRelocation &R, Edge::Kind Kind) {
+  return formatv("Invalid opcode {0:x8} for relocation: {1}",
+                 static_cast<uint32_t>(R.Wd), G.getEdgeKindName(Kind));
+}
+
+TEST(AArch32_ELF, readAddends) {
+  auto G = std::make_unique<LinkGraph>("foo", Triple("armv7-linux-gnueabi"), 4,
+                                       llvm::endianness::little,
+                                       getGenericEdgeKindName);
+
+  ArrayRef<char> Content = "hello, world!";
+  auto &Sec =
+      G->createSection("__data", orc::MemProt::Read | orc::MemProt::Write);
+  orc::ExecutorAddr B1Addr(0x1000);
+  auto &B = G->createContentBlock(Sec, Content, B1Addr, 4, 0);
+
+  Symbol &TargetSymbol = G->addAnonymousSymbol(B, 0, 4, false, false);
+  Edge InvalidEdge(FirstDataRelocation - 1, 0, TargetSymbol, 0);
+
+  auto ArmCfg = getArmConfigForCPUArch(ARMBuildAttrs::v7);
+
+  auto makeReadAddendError = [](LinkGraph &G, Block &B, Edge &E) {
+    return ("In graph " + G.getName() + ", section " +
+            B.getSection().getName() +
+            " can not read implicit addend for aarch32 edge kind " +
+            G.getEdgeKindName(E.getKind()))
+        .str();
+  };
+
+  EXPECT_THAT_EXPECTED(
+      readAddend(*G, B, InvalidEdge, ArmCfg),
+      FailedWithMessage(makeReadAddendError(*G, B, InvalidEdge)));
----------------
weliveindetail wrote:

Something like this maybe:
```
FailedWithMessage(testing::HasSubstr(
    "can not read implicit addend for aarch32 edge kind INVALID RELOCATION"))
```

I found one example here:
https://github.com/llvm/llvm-project/blob/release/17.x/llvm/unittests/DebugInfo/BTF/BTFParserTest.cpp#L216

It could also be `testing::EndsWith()` or I guess any other matcher from gmock: 
https://github.com/llvm/llvm-project/blob/release/17.x/third-party/unittest/googlemock/include/gmock/gmock-matchers.h#L3880

https://github.com/llvm/llvm-project/pull/69636