[lld] [llvm] [lld][AArch64][Build Attributes] Add support for AArch64 Build Attributes (PR #144082)

[Peter Smith via llvm-commits]

================
@@ -0,0 +1,62 @@
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+// RUN: llvm-mc -triple=aarch64 -filetype=obj %s -o %t11.o
+// RUN: llvm-mc -triple=aarch64 -filetype=obj merged-mixed-2.s -o %t12.o
+// RUN: llvm-mc -triple=aarch64 -filetype=obj merged-mixed-3.s -o %t13.o
+// RUN: ld.lld -r %t11.o %t12.o %t13.o -o %t.merged1.o
+// RUN: llvm-readelf -n %t.merged1.o | FileCheck %s --check-prefix=NOTE-MIXED
+
+// NOTE-MIXED: Displaying notes found in: .note.gnu.property
+// NOTE-MIXED-NEXT:   Owner                Data size 	Description
+// NOTE-MIXED-NEXT:   GNU                  0x00000028	NT_GNU_PROPERTY_TYPE_0 (property note)
+// NOTE-MIXED-NEXT:     Properties:    aarch64 feature: BTI, PAC
+// NOTE-MIXED-NEXT:         AArch64 PAuth ABI core info: platform 0x31 (unknown), version 0x13
+
+/// The Build attributes section appearing in the output of
+/// llvm-mc should not appear in the output of lld, because
+/// AArch64 build attributes are being transformed into .gnu.properties.
+
+// CHECK: .note.gnu.property
+// CHECK-NOT: .ARM.attributes
+
+.aeabi_subsection aeabi_pauthabi, required, uleb128
+.aeabi_attribute Tag_PAuth_Platform, 49
+.aeabi_attribute Tag_PAuth_Schema, 19
+.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
+
+
+//--- merged-mixed-2.s
+.section ".note.gnu.property", "a"
+  .long 4           // Name length is always 4 ("GNU")
+  .long end - begin // Data length
+  .long 5           // Type: NT_GNU_PROPERTY_TYPE_0
+  .asciz "GNU"      // Name
+  .p2align 3
+begin:
+  .long 0xc0000000 // GNU_PROPERTY_AARCH64_FEATURE_1_AND
+  .long 4
+  .long 7          // GNU_PROPERTY_AARCH64_FEATURE_1_BTI, PAC and GCS
+  .long 0
+  // PAuth ABI property note
+  .long 0xc0000001  // Type: GNU_PROPERTY_AARCH64_FEATURE_PAUTH
+  .long 16          // Data size
+  .quad 49          // PAuth ABI platform
+  .quad 19          // PAuth ABI version
+  .p2align 3        // Align to 8 byte for 64 bit
+end:
+
+//--- merged-mixed-3.s
+.section .note.gnu.property, "a"
+  .align 4
+  .long 4                      // namesz
----------------
smithp35 wrote:

Apologies for the nit picks, but if I don't someone else will!

For the bits that are identical between the two property sections, can you use the same comments. It helps show what parts are identical and where the differences are.

https://github.com/llvm/llvm-project/pull/144082