[MC] set OpenBSD's ELFOSABI by default (#98158)

Ericson2314 · web-flow · commit b64c1de714c5 · 2024-07-11T09:10:24.000-04:00
This matches what is done for FreeBSD. OpenBSD has a few special program header types, and other such ELF extensions. Setting the ELFOSABI like so will allow LLD to support them without needlessly impacting non-OpenBSD ELFs. Testing strategy matches 06cecdc.
diff --git a/llvm/include/llvm/MC/MCELFObjectWriter.h b/llvm/include/llvm/MC/MCELFObjectWriter.h
@@ -78,6 +78,8 @@ class MCELFObjectTargetWriter : public MCObjectTargetWriter {
         return ELF::ELFOSABI_FREEBSD;
       case Triple::Solaris:
         return ELF::ELFOSABI_SOLARIS;
+      case Triple::OpenBSD:
+        return ELF::ELFOSABI_OPENBSD;
       default:
         return ELF::ELFOSABI_NONE;
     }
diff --git a/llvm/test/MC/ELF/osabi.s b/llvm/test/MC/ELF/osabi.s
@@ -10,3 +10,7 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-freebsd %s | llvm-readobj -h - | \
 # RUN:   FileCheck %s --check-prefix=FREEBSD
 # FREEBSD: OS/ABI: FreeBSD
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-openbsd %s | llvm-readobj -h - | \
+# RUN:   FileCheck %s --check-prefix=OPENBSD
+# OPENBSD: OS/ABI: OpenBSD

Original file line number	Diff line number	Diff line change
`@@ -78,6 +78,8 @@ class MCELFObjectTargetWriter : public MCObjectTargetWriter {`
`78`	`78`	`return ELF::ELFOSABI_FREEBSD;`
`79`	`79`	`case Triple::Solaris:`
`80`	`80`	`return ELF::ELFOSABI_SOLARIS;`
	`81`	`+ case Triple::OpenBSD:`
	`82`	`+ return ELF::ELFOSABI_OPENBSD;`
`81`	`83`	`default:`
`82`	`84`	`return ELF::ELFOSABI_NONE;`
`83`	`85`	`}`