[llvm] 92c527e - [llvm/Object] - Make dyn_cast<XCOFFObjectFile> work as it should.

[Georgii Rymar via llvm-commits]

Author: Georgii Rymar
Date: 2020-08-26T15:09:55+03:00
New Revision: 92c527e5a2b49fb1213ceda97738d4caf414666a

URL: https://github.com/llvm/llvm-project/commit/92c527e5a2b49fb1213ceda97738d4caf414666a
DIFF: https://github.com/llvm/llvm-project/commit/92c527e5a2b49fb1213ceda97738d4caf414666a.diff

LOG: [llvm/Object] - Make dyn_cast<XCOFFObjectFile> work as it should.

Currently, `dyn_cast<XCOFFObjectFile>` always does cast and returns a pointer,
even when we pass `ELF`/`Wasm`/`Mach-O` or `COFF` instead of `XCOFF`.

It happens because `XCOFFObjectFile` class does not implement `classof`.
I've fixed it and added a unit test.

Differential revision: https://reviews.llvm.org/D86542

Added: 
    

Modified: 
    llvm/include/llvm/Object/XCOFFObjectFile.h
    llvm/unittests/Object/XCOFFObjectFileTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Object/XCOFFObjectFile.h b/llvm/include/llvm/Object/XCOFFObjectFile.h
index 53caeae0bdcc..fbc542fd3e6d 100644
--- a/llvm/include/llvm/Object/XCOFFObjectFile.h
+++ b/llvm/include/llvm/Object/XCOFFObjectFile.h
@@ -372,6 +372,8 @@ class XCOFFObjectFile : public ObjectFile {
 
   Expected<ArrayRef<XCOFFRelocation32>>
   relocations(const XCOFFSectionHeader32 &) const;
+
+  static bool classof(const Binary *B) { return B->isXCOFF(); }
 }; // XCOFFObjectFile
 
 class XCOFFSymbolRef {

diff  --git a/llvm/unittests/Object/XCOFFObjectFileTest.cpp b/llvm/unittests/Object/XCOFFObjectFileTest.cpp
index cb0004585d23..47e200c12cfe 100644
--- a/llvm/unittests/Object/XCOFFObjectFileTest.cpp
+++ b/llvm/unittests/Object/XCOFFObjectFileTest.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Object/XCOFFObjectFile.h"
 #include "llvm/Testing/Support/Error.h"
 #include "gtest/gtest.h"
@@ -13,6 +14,24 @@
 using namespace llvm;
 using namespace llvm::object;
 
+TEST(XCOFFObjectFileTest, XCOFFObjectType) {
+  // Create an arbitrary object of a non-XCOFF type and test that
+  // dyn_cast<XCOFFObjectFile> returns null for it.
+  char Buf[sizeof(typename ELF64LE::Ehdr)] = {};
+  memcpy(Buf, "\177ELF", 4);
+
+  auto *EHdr = reinterpret_cast<typename ELF64LE::Ehdr *>(Buf);
+  EHdr->e_ident[llvm::ELF::EI_CLASS] = llvm::ELF::ELFCLASS64;
+  EHdr->e_ident[llvm::ELF::EI_DATA] = llvm::ELF::ELFDATA2LSB;
+
+  MemoryBufferRef Source(StringRef(Buf, sizeof(Buf)), "non-XCOFF");
+  Expected<std::unique_ptr<ObjectFile>> ObjOrErr =
+      ObjectFile::createObjectFile(Source);
+  ASSERT_THAT_EXPECTED(ObjOrErr, Succeeded());
+
+  EXPECT_TRUE(dyn_cast<XCOFFObjectFile>((*ObjOrErr).get()) == nullptr);
+}
+
 TEST(XCOFFObjectFileTest, doesXCOFFTracebackTableBegin) {
   EXPECT_TRUE(doesXCOFFTracebackTableBegin({0, 0, 0, 0}));
   EXPECT_TRUE(doesXCOFFTracebackTableBegin({0, 0, 0, 0, 1}));