[PATCH] D59986: [ELF] Respect NonAlloc when copying flags from the previous sections

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added reviewers: ruiu, grimar.
Herald added subscribers: llvm-commits, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

If the output section contains only symbol assignments, we copy flags
from the previous sections. Don't set SHF_ALLOC if NonAlloc is true.

We also have to change the type from SHT_NOBITS to SHT_PROGBITS.
In BFD, bfd_elf_get_default_section_type maps non-alloctable sections to SHT_PROGBITS.

Fixes PR38626


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D59986

Files:
  ELF/LinkerScript.cpp
  ELF/ScriptParser.cpp
  test/ELF/linkerscript/info-section-type.s


Index: test/ELF/linkerscript/info-section-type.s
===================================================================
--- test/ELF/linkerscript/info-section-type.s
+++ test/ELF/linkerscript/info-section-type.s
@@ -29,6 +29,10 @@
 # RUN: ld.lld -o %t --script %t.script %t.o
 # RUN: llvm-readobj -sections %t | FileCheck %s --check-prefix=NONALLOC
 
+# RUN: echo "SECTIONS { .bar (INFO) : { . += 1; } };" > %t.script
+# RUN: ld.lld -o %t --script %t.script %t.o
+# RUN: llvm-readobj -sections %t | FileCheck %s --check-prefix=NONALLOC
+
 # RUN: echo "SECTIONS { .bar 0x20000 (INFO) : { *(.foo) } };" > %t.script
 # RUN: ld.lld -o %t --script %t.script %t.o
 # RUN: llvm-readobj -sections %t | FileCheck %s --check-prefix=NONALLOC
Index: ELF/ScriptParser.cpp
===================================================================
--- ELF/ScriptParser.cpp
+++ ELF/ScriptParser.cpp
@@ -752,6 +752,7 @@
   } else {
     skip(); // This is "COPY", "INFO" or "OVERLAY".
     Cmd->NonAlloc = true;
+    Cmd->Type = SHT_PROGBITS;
   }
   expect(")");
   return true;
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -886,7 +886,8 @@
     // in case it is empty.
     bool IsEmpty = getInputSections(Sec).empty();
     if (IsEmpty)
-      Sec->Flags = Flags & (SHF_ALLOC | SHF_WRITE | SHF_EXECINSTR);
+      Sec->Flags =
+          Flags & ((Sec->NonAlloc ? 0 : SHF_ALLOC) | SHF_WRITE | SHF_EXECINSTR);
 
     if (IsEmpty && isDiscardable(*Sec)) {
       Sec->Live = false;


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