[ELF] Attempt to set the OS when using 'makeTriple()' (#76992)

Summary:
This patch fixes up the `makeTriple()` interface to emit append the
operating system information when it is readily avaialble from the ELF.
The main motivation for this is so the GPU architectures can be easily
identified correctly when given and ELF. E.g. we want
`amdgpu-amd-amdhsa` as the output and not `amdgpu--`.

This required adding support for the CUDA OS/ABI, which is easily found
to be `0x33` when using `readelf`.

1 files changed, 34 insertions, 7 deletions

diff --git a/llvm/unittests/Object/ELFObjectFileTest.cpp b/llvm/unittests/Object/ELFObjectFileTest.cpp
index 2878ca088cd7..e7619ded494e 100644
--- a/llvm/unittests/Object/ELFObjectFileTest.cpp
+++ b/llvm/unittests/Object/ELFObjectFileTest.cpp
@@ -36,7 +36,8 @@ struct DataForTest {
 
   template <typename T>
   std::vector<uint8_t> makeElfData(uint8_t Class, uint8_t Encoding,
-                                   uint16_t Machine) {
+                                   uint16_t Machine, uint8_t OS,
+                                   uint16_t Flags) {
     T Ehdr{}; // Zero-initialise the header.
     Ehdr.e_ident[ELF::EI_MAG0] = 0x7f;
     Ehdr.e_ident[ELF::EI_MAG1] = 'E';
@@ -45,9 +46,11 @@ struct DataForTest {
     Ehdr.e_ident[ELF::EI_CLASS] = Class;
     Ehdr.e_ident[ELF::EI_DATA] = Encoding;
     Ehdr.e_ident[ELF::EI_VERSION] = 1;
+    Ehdr.e_ident[ELF::EI_OSABI] = OS;
     Ehdr.e_type = ELF::ET_REL;
     Ehdr.e_machine = Machine;
     Ehdr.e_version = 1;
+    Ehdr.e_flags = Flags;
     Ehdr.e_ehsize = sizeof(T);
 
     bool IsLittleEndian = Encoding == ELF::ELFDATA2LSB;
@@ -64,12 +67,13 @@ struct DataForTest {
     return Bytes;
   }
 
-  DataForTest(uint8_t Class, uint8_t Encoding, uint16_t Machine) {
+  DataForTest(uint8_t Class, uint8_t Encoding, uint16_t Machine,
+              uint8_t OS = ELF::ELFOSABI_NONE, uint16_t Flags = 0) {
     if (Class == ELF::ELFCLASS64)
-      Data = makeElfData<ELF::Elf64_Ehdr>(Class, Encoding, Machine);
+      Data = makeElfData<ELF::Elf64_Ehdr>(Class, Encoding, Machine, OS, Flags);
     else {
       assert(Class == ELF::ELFCLASS32);
-      Data = makeElfData<ELF::Elf32_Ehdr>(Class, Encoding, Machine);
+      Data = makeElfData<ELF::Elf32_Ehdr>(Class, Encoding, Machine, OS, Flags);
     }
   }
 };
@@ -287,6 +291,30 @@ TEST(ELFObjectFileTest, MachineTestForXtensa) {
     checkFormatAndArch(Data, Formats[Idx], Triple::xtensa);
 }
 
+TEST(ELFObjectFileTest, CheckOSAndTriple) {
+  std::tuple<uint16_t, uint8_t, StringRef> Formats[] = {
+      {ELF::EM_AMDGPU, ELF::ELFOSABI_AMDGPU_HSA, "amdgcn-amd-amdhsa"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_LINUX, "x86_64--linux"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_NETBSD, "x86_64--netbsd"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_HURD, "x86_64--hurd"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_SOLARIS, "x86_64--solaris"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_AIX, "x86_64--aix"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_FREEBSD, "x86_64--freebsd"},
+      {ELF::EM_X86_64, ELF::ELFOSABI_OPENBSD, "x86_64--openbsd"},
+      {ELF::EM_CUDA, ELF::ELFOSABI_CUDA, "nvptx64-nvidia-cuda"}};
+  for (auto [Machine, OS, Triple] : Formats) {
+    const DataForTest D(ELF::ELFCLASS64, ELF::ELFDATA2LSB, Machine, OS,
+                        ELF::EF_AMDGPU_MACH_AMDGCN_LAST);
+    Expected<std::unique_ptr<ObjectFile>> ELFObjOrErr =
+        object::ObjectFile::createELFObjectFile(
+            MemoryBufferRef(toStringRef(D.Data), "dummyELF"));
+    ASSERT_THAT_EXPECTED(ELFObjOrErr, Succeeded());
+
+    auto &ELFObj = **ELFObjOrErr;
+    EXPECT_EQ(Triple, ELFObj.makeTriple().getTriple());
+  }
+}
+
 // ELF relative relocation type test.
 TEST(ELFObjectFileTest, RelativeRelocationTypeTest) {
   EXPECT_EQ(ELF::R_CKCORE_RELATIVE, getELFRelativeRelocationType(ELF::EM_CSKY));
@@ -1273,13 +1301,12 @@ Sections:
 )";
 
   auto ErroringMatcher = [](const Elf_Shdr &Sec) -> Expected<bool> {
-    if(Sec.sh_type == ELF::SHT_PROGBITS)
+    if (Sec.sh_type == ELF::SHT_PROGBITS)
       return createError("This was supposed to fail.");
     return false;
   };
 
-  DoCheckFails(OneTextSection, ErroringMatcher,
-               "This was supposed to fail.");
+  DoCheckFails(OneTextSection, ErroringMatcher, "This was supposed to fail.");
 
   StringRef MissingRelocatableContent = R"(
 Sections: