[llvm] [RISCV] Add basic Mach-O triple support. (PR #141682)

[Fangrui Song via llvm-commits]

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@@ -60,7 +60,12 @@ static MCRegisterInfo *createRISCVMCRegisterInfo(const Triple &TT) {
 static MCAsmInfo *createRISCVMCAsmInfo(const MCRegisterInfo &MRI,
                                        const Triple &TT,
                                        const MCTargetOptions &Options) {
-  MCAsmInfo *MAI = new RISCVMCAsmInfo(TT);
+  MCAsmInfo *MAI = nullptr;
+  if (TT.isOSBinFormatELF())
+    MAI = new RISCVMCAsmInfo(TT);
+  else if (TT.isOSBinFormatMachO())
+    MAI = new RISCVMCAsmInfoDarwin();
+  assert(MAI && "Missing MCAsmInfo.");
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MaskRay wrote:

`reportFatalUsageError("unsupported object format");`

See #147880

https://github.com/llvm/llvm-project/pull/141682