[llvm] [MC][AMDGPU] Support .reloc BFD_RELOC_{NONE, 32, 64} (PR #114617)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-amdgpu

Author: Ethan Luis McDonough (EthanLuisMcDonough)

<details>
<summary>Changes</summary>

Emitting BFD_RELOC_* reloc directives can cause internal errors on AMDGPU.

---
Full diff: https://github.com/llvm/llvm-project/pull/114617.diff


1 Files Affected:

- (modified) llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp (+9-4) 


``````````diff
diff --git a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
index c2d2ca0f90f930..3172a83e5a1fe0 100644
--- a/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
+++ b/llvm/lib/Target/AMDGPU/MCTargetDesc/AMDGPUAsmBackend.cpp
@@ -163,12 +163,17 @@ void AMDGPUAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
 
 std::optional<MCFixupKind>
 AMDGPUAsmBackend::getFixupKind(StringRef Name) const {
-  return StringSwitch<std::optional<MCFixupKind>>(Name)
-#define ELF_RELOC(Name, Value)                                                 \
-  .Case(#Name, MCFixupKind(FirstLiteralRelocationKind + Value))
+  auto Type = StringSwitch<unsigned>(Name)
+#define ELF_RELOC(Name, Value) .Case(#Name, Value)
 #include "llvm/BinaryFormat/ELFRelocs/AMDGPU.def"
 #undef ELF_RELOC
-      .Default(std::nullopt);
+                  .Case("BFD_RELOC_NONE", ELF::R_AMDGPU_NONE)
+                  .Case("BFD_RELOC_32", ELF::R_AMDGPU_ABS32)
+                  .Case("BFD_RELOC_64", ELF::R_AMDGPU_ABS64)
+                  .Default(-1u);
+  if (Type != -1u)
+    return static_cast<MCFixupKind>(FirstLiteralRelocationKind + Type);
+  return std::nullopt;
 }
 
 const MCFixupKindInfo &AMDGPUAsmBackend::getFixupKindInfo(

``````````

</details>


https://github.com/llvm/llvm-project/pull/114617