[LLD][ELF][AArch64] Discard .ARM.attributes sections

lld/ELF/InputFiles.cpp

@@ -639,6 +639,13 @@ template <class ELFT> void ObjFile<ELFT>::parse(bool ignoreComdats) {
       }
       break;
     case EM_AARCH64:
+      // FIXME: BuildAttributes have been implemented in llvm, but not yet in
+      // lld. Remove the section so that it does not accumulate in the output
+      // file. When support is implemented we expect not to output a build
+      // attributes section in files of type ET_EXEC or ET_SHARED, but ld -r
+      // ouptut will need a single merged attributes section.
+      if (sec.sh_type == SHT_AARCH64_ATTRIBUTES)
+        sections[i] = &InputSection::discarded;
       // Producing a static binary with MTE globals is not currently supported,
       // remove all SHT_AARCH64_MEMTAG_GLOBALS_STATIC sections as they're unused
       // medatada, and we don't want them to end up in the output file for

lld/test/ELF/aarch64-build-attributes-output.s

@@ -0,0 +1,26 @@
+// REQUIRES: aarch64
+// RUN: llvm-mc -triple=aarch64 %s -filetype=obj -o %t.o
+// RUN: ld.lld %t.o --shared -o %t.so
+// RUN: llvm-readelf --sections %t.so | FileCheck %s
+// RUN: ld.lld %t.o -o %t
+// RUN: llvm-readelf --sections %t | FileCheck %s
+// RUN: ld.lld -r %t.o -o %t2.o
+// RUN: llvm-readelf --sections %t2.o | FileCheck %s
+
+/// File has a Build attributes section. This should not appear in
+/// ET_EXEC or ET_SHARED files as there is no requirement for it to
+/// do so. FIXME, the ld -r (relocatable link) should output a single
+/// merged build attributes section. WHen full support is added in
+/// ld.lld this test should be updated.
+
+// CHECK-NOT: .ARM.attributes
+
+.aeabi_subsection aeabi_feature_and_bits, optional, uleb128
+.aeabi_attribute Tag_Feature_BTI, 1
+.aeabi_attribute Tag_Feature_PAC, 1
+.aeabi_attribute Tag_Feature_GCS, 1
+
+.global _start
+.type _start, %function
+_start:
+ret