From 05fb769b72834c62de3ac2d282e4949e77996c60 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i@maskray.me>
Date: Thu, 29 Jun 2023 17:59:15 -0700
Subject: [PATCH] [AArch64][MachO] Drop a 2015 ld64 workaround avoiding local
 relocations

Commit d6223a24718df3c30b67422c2eb6d0e93af9c4e8 introduced an ld64 workaround
that disables local relocations for many pointer-sized relocations (e.g.
relocations referencing `__DATA,__literal*`).

ld64 has been fixed long ago (2015). Drop this workaround so that the
behavior matches x86-64.

Reviewed By: pete

Differential Revision: https://reviews.llvm.org/D152831
---
 .../Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp  |  8 +++-----
 llvm/test/MC/MachO/AArch64/ld64-workaround.s                 | 12 ++++++------
 llvm/test/MC/MachO/AArch64/mergeable.s                       |  4 +---
 3 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
index 012661e..04bd852 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
@@ -139,13 +139,11 @@ static bool canUseLocalRelocation(const MCSectionMachO &Section,
     return false;
 
   if (RefSec.getSegmentName() == "__DATA" &&
-      RefSec.getName() == "__objc_classrefs")
+      (RefSec.getName() == "__cfstring" ||
+       RefSec.getName() == "__objc_classrefs"))
     return false;
 
-  // FIXME: ld64 currently handles internal pointer-sized relocations
-  // incorrectly (applying the addend twice). We should be able to return true
-  // unconditionally by this point when that's fixed.
-  return false;
+  return true;
 }
 
 void AArch64MachObjectWriter::recordRelocation(
diff --git a/llvm/test/MC/MachO/AArch64/ld64-workaround.s b/llvm/test/MC/MachO/AArch64/ld64-workaround.s
index 807580c..8e59b07 100644
--- a/llvm/test/MC/MachO/AArch64/ld64-workaround.s
+++ b/llvm/test/MC/MachO/AArch64/ld64-workaround.s
@@ -1,8 +1,8 @@
 ; RUN: llvm-mc -triple arm64-apple-darwin10 %s -filetype=obj -o - | llvm-readobj -r --expand-relocs - | FileCheck %s
 
-; Test that we produce an external relocation. This is a known and temporary bug
-; in ld64, where it mishandles pointer-sized internal relocations. We should be
-; able to remove this entirely soon.
+/// To work around an ld64 arm64 bug before 2015, we used to disable local
+/// relocations for many pointer-sized relocations. Test that the workaround
+/// is dropped and the behavior now matches x86-64.
 
 // CHECK:      Relocations [
 // CHECK-NEXT:   Section __data {
@@ -11,21 +11,21 @@
 // CHECK-NEXT:       PCRel: 0
 // CHECK-NEXT:       Length: 3
 // CHECK-NEXT:       Type: ARM64_RELOC_UNSIGNED (0)
-// CHECK-NEXT:       Symbol: Llit16
+// CHECK-NEXT:       Section: __literal16
 // CHECK-NEXT:     }
 // CHECK-NEXT:     Relocation {
 // CHECK-NEXT:       Offset: 0x10
 // CHECK-NEXT:       PCRel: 0
 // CHECK-NEXT:       Length: 3
 // CHECK-NEXT:       Type: ARM64_RELOC_UNSIGNED (0)
-// CHECK-NEXT:       Symbol: Llit8
+// CHECK-NEXT:       Section: __literal8
 // CHECK-NEXT:     }
 // CHECK-NEXT:     Relocation {
 // CHECK-NEXT:       Offset: 0x8
 // CHECK-NEXT:       PCRel: 0
 // CHECK-NEXT:       Length: 3
 // CHECK-NEXT:       Type: ARM64_RELOC_UNSIGNED (0)
-// CHECK-NEXT:       Symbol: Llit4
+// CHECK-NEXT:       Section: __literal4
 // CHECK-NEXT:     }
 // CHECK-NEXT:     Relocation {
 // CHECK-NEXT:       Offset: 0x0
diff --git a/llvm/test/MC/MachO/AArch64/mergeable.s b/llvm/test/MC/MachO/AArch64/mergeable.s
index 8621b25..4aa2d01 100644
--- a/llvm/test/MC/MachO/AArch64/mergeable.s
+++ b/llvm/test/MC/MachO/AArch64/mergeable.s
@@ -1,6 +1,4 @@
 // RUN: llvm-mc -triple aarch64-apple-darwin14 %s -filetype=obj -o - | llvm-readobj -r --expand-relocs - | FileCheck %s
-// FIXME: the final relocation should be internal, but the linker doesn't
-// currently handle the it correctly.
 
 // Test that we "S + K" produce a relocation with a symbol, but just S produces
 // a relocation with the section.
@@ -47,7 +45,7 @@ L1:
 // CHECK-NEXT:       PCRel: 0
 // CHECK-NEXT:       Length: 3
 // CHECK-NEXT:       Type: ARM64_RELOC_UNSIGNED (0)
-// CHECK-NEXT:       Symbol: L0
+// CHECK-NEXT:       Section: __literal4
 // CHECK-NEXT:     }
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
-- 
2.7.4