[PATCH] D75536: [LLD] Add support for --unique option

[Dave Bozier via Phabricator via llvm-commits]

davidb updated this revision to Diff 248045.
davidb added a comment.

- review comments


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D75536/new/

https://reviews.llvm.org/D75536

Files:
  lld/ELF/Config.h
  lld/ELF/Driver.cpp
  lld/ELF/LinkerScript.cpp
  lld/ELF/Options.td
  lld/test/ELF/unique-orphans.s


Index: lld/test/ELF/unique-orphans.s
===================================================================
--- /dev/null
+++ lld/test/ELF/unique-orphans.s
@@ -0,0 +1,29 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+
+.section .foo,"a", at progbits,unique,1
+.byte 1
+
+.section .foo,"a", at progbits,unique,2
+.byte 2
+
+.section .foo,"a", at progbits,unique,3
+.byte 3
+
+# We should have 2 instance of orphan section .text.foo
+# RUN: ld.lld %t.o -r -o %t.ro --unique
+# RUN: llvm-objdump -h %t.ro | FileCheck --check-prefix UNIQUE_R %s
+# UNIQUE_R-COUNT-3: .foo
+# UNIQUE_R-NOT: .foo
+
+# We should have 2 instance of orphan section .text.foo
+# RUN: ld.lld %t.o -o %t.elf --unique 
+# RUN: llvm-objdump -h %t.elf | FileCheck --check-prefix UNIQUE %s
+# UNIQUE-COUNT-3: .foo
+# UNIQUE-NOT: .foo
+
+# RUN: echo 'SECTIONS { .foo : { *(.foo) }}' > %t.script
+# RUN: ld.lld %t.o -o %t2.elf -T %t.script --unique 
+# RUN: llvm-objdump -h %t2.elf | FileCheck --check-prefix UNIQUE_SCRIPT %s
+# UNIQUE_SCRIPT: .foo
+# UNIQUE_SCRIPT-NOT: .foo
\ No newline at end of file
Index: lld/ELF/Options.td
===================================================================
--- lld/ELF/Options.td
+++ lld/ELF/Options.td
@@ -374,6 +374,9 @@
 defm undefined_glob: Eq<"undefined-glob", "Force undefined symbol during linking">,
   MetaVarName<"<pattern>">;
 
+
+def unique: F<"unique">, HelpText<"Creates a separate output section for every orphan input section">;
+
 defm unresolved_symbols:
   Eq<"unresolved-symbols", "Determine how to handle unresolved symbols">;
 
Index: lld/ELF/LinkerScript.cpp
===================================================================
--- lld/ELF/LinkerScript.cpp
+++ lld/ELF/LinkerScript.cpp
@@ -684,7 +684,10 @@
       orphanSections.push_back(s);
 
       StringRef name = getOutputSectionName(s);
-      if (OutputSection *sec = findByName(sectionCommands, name)) {
+
+      if (config->unique) {
+        v.push_back(createSection(s, name));
+      } else if (OutputSection *sec = findByName(sectionCommands, name)) {
         sec->recordSection(s);
       } else {
         if (OutputSection *os = addInputSec(map, s, name))
@@ -693,6 +696,7 @@
                s->getOutputSection()->sectionIndex == UINT32_MAX);
       }
     }
+    }
 
     if (config->relocatable)
       for (InputSectionBase *depSec : s->dependentSections)
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -967,6 +967,7 @@
   config->splitStackAdjustSize = args::getInteger(args, OPT_split_stack_adjust_size, 16384);
   config->strip = getStrip(args);
   config->sysroot = args.getLastArgValue(OPT_sysroot);
+  config->unique = args.hasArg(OPT_unique);
   config->target1Rel = args.hasFlag(OPT_target1_rel, OPT_target1_abs, false);
   config->target2 = getTarget2(args);
   config->thinLTOCacheDir = args.getLastArgValue(OPT_thinlto_cache_dir);
Index: lld/ELF/Config.h
===================================================================
--- lld/ELF/Config.h
+++ lld/ELF/Config.h
@@ -194,6 +194,7 @@
   bool timeTraceEnabled;
   bool tocOptimize;
   bool undefinedVersion;
+  bool unique = false;
   bool useAndroidRelrTags = false;
   bool warnBackrefs;
   bool warnCommon;


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