[PATCH] D34195: [ELF] Mark symbols referenced from linker script as live

[Petr Hosek via Phabricator via llvm-commits]

phosek created this revision.
phosek added a project: lld.
Herald added a subscriber: emaste.

This is necessary to ensure that sections containing symbols referenced
from linker scripts (e.g. in data commands) don't get GC'd.


Repository:
  rL LLVM

https://reviews.llvm.org/D34195

Files:
  ELF/MarkLive.cpp
  test/ELF/linkerscript/data-commands-gc.s


Index: test/ELF/linkerscript/data-commands-gc.s
===================================================================
--- /dev/null
+++ test/ELF/linkerscript/data-commands-gc.s
@@ -0,0 +1,22 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "SECTIONS                \
+# RUN:  {                            \
+# RUN:    .text : {                  \
+# RUN:      *(.text*)                \
+# RUN:      QUAD(bar)                \
+# RUN:    }                          \
+# RUN:  }" > %t.script
+# RUN: ld.lld --gc-sections -o %t %t.o --script %t.script | FileCheck -allow-empty %s
+
+# CHECK-NOT: unable to evaluate expression: input section .rodata.bar has no output section assigned
+
+.section .rodata.bar
+.quad 0x1122334455667788
+.global bar
+bar:
+
+.section .text
+.global _start
+_start:
+  nop
Index: ELF/MarkLive.cpp
===================================================================
--- ELF/MarkLive.cpp
+++ ELF/MarkLive.cpp
@@ -230,6 +230,8 @@
   MarkSymbol(Symtab<ELFT>::X->find(Config->Fini));
   for (StringRef S : Config->Undefined)
     MarkSymbol(Symtab<ELFT>::X->find(S));
+  for (StringRef S : Script->Opt.ReferencedSymbols)
+    MarkSymbol(Symtab<ELFT>::X->find(S));
 
   // Preserve externally-visible symbols if the symbols defined by this
   // file can interrupt other ELF file's symbols at runtime.


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