[PATCH] D93257: [lld-macho] Don't emit rebase opcodes for relocs in TLV sections

[Jez Ng via Phabricator via llvm-commits]

int3 created this revision.
int3 added a reviewer: lld-macho.
int3 requested review of this revision.
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Herald added a subscriber: llvm-commits.

Their addresses are already encoded as already section-relative offsets,
so there's no need to rebase them at runtime. D85080: [lld-macho] Support static linking of thread-locals <https://reviews.llvm.org/D85080> has some context
on the weirdness of TLV sections.

Fixes llvm.org/PR48491.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D93257

Files:
  lld/MachO/Arch/X86_64.cpp
  lld/test/MachO/tlv-dylib.s
  lld/test/MachO/tlv.s


Index: lld/test/MachO/tlv.s
===================================================================
--- lld/test/MachO/tlv.s
+++ lld/test/MachO/tlv.s
@@ -1,9 +1,14 @@
 # REQUIRES: x86
 # RUN: mkdir -p %t
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t/test.o
+
 # RUN: %lld -lSystem -o %t/test %t/test.o
 # RUN: llvm-readobj --file-headers %t/test | FileCheck %s --check-prefix=HEADER
-# RUN: llvm-objdump -D %t/test | FileCheck %s
+# RUN: llvm-objdump -D --rebase %t/test | FileCheck %s
+
+# RUN: %lld -lSystem -pie -o %t/test %t/test.o
+# RUN: llvm-readobj --file-headers %t/test | FileCheck %s --check-prefix=HEADER
+# RUN: llvm-objdump -D --rebase %t/test | FileCheck %s
 
 # HEADER: MH_HAS_TLV_DESCRIPTORS
 
@@ -36,6 +41,11 @@
 # CHECK-NEXT:  00 00
 # CHECK-NEXT:  00 00
 
+## Make sure we don't emit rebase opcodes for relocations in __thread_vars.
+# CHECK:       Rebase table:
+# CHECK-NEXT:  segment  section            address     type
+# CHECK-EMPTY:
+
 .globl _main
 _main:
   mov _foo at TLVP(%rip), %rax
Index: lld/test/MachO/tlv-dylib.s
===================================================================
--- lld/test/MachO/tlv-dylib.s
+++ lld/test/MachO/tlv-dylib.s
@@ -4,9 +4,14 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/libtlv.s -o %t/libtlv.o
 # RUN: %lld -dylib -install_name @executable_path/libtlv.dylib \
 # RUN:   -lSystem -o %t/libtlv.dylib %t/libtlv.o
-# RUN: llvm-objdump --exports-trie -d --no-show-raw-insn %t/libtlv.dylib | FileCheck %s --check-prefix=DYLIB
+# RUN: llvm-objdump --macho --exports-trie --rebase %t/libtlv.dylib | \
+# RUN:   FileCheck %s --check-prefix=DYLIB
 # DYLIB-DAG: _foo [per-thread]
 # DYLIB-DAG: _bar [per-thread]
+## Make sure we don't emit rebase opcodes for relocations in __thread_vars.
+# DYLIB:       Rebase table:
+# DYLIB-NEXT:  segment  section            address     type
+# DYLIB-EMPTY:
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/test.s -o %t/test.o
 # RUN: %lld -lSystem -L%t -ltlv %t/test.o -o %t/test
Index: lld/MachO/Arch/X86_64.cpp
===================================================================
--- lld/MachO/Arch/X86_64.cpp
+++ lld/MachO/Arch/X86_64.cpp
@@ -248,7 +248,11 @@
         return;
       }
     }
-    addNonLazyBindingEntries(sym, isec, r.offset, r.addend);
+    // References from thread-local variable sections are treated as offsets
+    // relative to the start of the referent section, and therefore have no
+    // need of rebase opcodes.
+    if (!isThreadLocalVariables(isec->flags))
+      addNonLazyBindingEntries(sym, isec, r.offset, r.addend);
     break;
   }
   case X86_64_RELOC_SIGNED:


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