[lld] b00c8ab - Revert "[ELF] --gc-sections: allow GC on reserved sections in a group"

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2021-07-27T16:34:32-07:00
New Revision: b00c8ab1b915d7f32ad7a60255f33f210e12a3c6

URL: https://github.com/llvm/llvm-project/commit/b00c8ab1b915d7f32ad7a60255f33f210e12a3c6
DIFF: https://github.com/llvm/llvm-project/commit/b00c8ab1b915d7f32ad7a60255f33f210e12a3c6.diff

LOG: Revert "[ELF] --gc-sections: allow GC on reserved sections in a group"

clang may place dynamic initializations for explicitly specialized class
template static data members in comdat.
Such in-comdat SHT_INIT_ARRAY was an abuse but we have to work around it for a while.

Added: 
    

Modified: 
    lld/ELF/MarkLive.cpp
    lld/test/ELF/gc-sections-group.s

Removed: 
    


################################################################################
diff  --git a/lld/ELF/MarkLive.cpp b/lld/ELF/MarkLive.cpp
index 0378a19e1919d..e828429b421c3 100644
--- a/lld/ELF/MarkLive.cpp
+++ b/lld/ELF/MarkLive.cpp
@@ -168,15 +168,14 @@ void MarkLive<ELFT>::scanEhFrameSection(EhInputSection &eh,
 // garbage-collected. This function returns true if a given section is such
 // section.
 static bool isReserved(InputSectionBase *sec) {
-  if (sec->nextInSectionGroup)
-    return false;
-
   switch (sec->type) {
   case SHT_FINI_ARRAY:
   case SHT_INIT_ARRAY:
   case SHT_PREINIT_ARRAY:
-  case SHT_NOTE:
     return true;
+  case SHT_NOTE:
+    // SHT_NOTE sections in a group are subject to garbage collection.
+    return !sec->nextInSectionGroup;
   default:
     StringRef s = sec->name;
     return s.startswith(".ctors") || s.startswith(".dtors") ||

diff  --git a/lld/test/ELF/gc-sections-group.s b/lld/test/ELF/gc-sections-group.s
index 0b74f6fa707ea..da4cad98f3653 100644
--- a/lld/test/ELF/gc-sections-group.s
+++ b/lld/test/ELF/gc-sections-group.s
@@ -10,7 +10,6 @@
 ## .mynote.ccc is retained because it is not in a group.
 # CHECK-DEAD-NOT: Name: .myanote.aaa
 # CHECK-DEAD-NOT: Name: .mytext.aaa
-# CHECK-DEAD-NOT: Name: .myinit_array.aaa
 # CHECK-DEAD-NOT: Name: .mybss.aaa
 # CHECK-DEAD-NOT: Name: .mynote.aaa
 # CHECK-DEAD-NOT: Name: .myanote.bbb
@@ -33,7 +32,6 @@
 
 # CHECK-LIVE-GROUP: Name: .myanote.aaa
 # CHECK-LIVE-GROUP: Name: .mytext.aaa
-# CHECK-LIVE-GROUP: Name: .myinit_array.aaa
 # CHECK-LIVE-GROUP: Name: .mybss.aaa
 # CHECK-LIVE-GROUP: Name: .mynote.aaa
 # CHECK-LIVE-GROUP-NOT: Name: .myanote.bbb
@@ -56,7 +54,6 @@
 
 # CHECK-LIVE-COMDAT-NOT: Name: .myanote.aaa
 # CHECK-LIVE-COMDAT-NOT: Name: .mytext.aaa
-# CHECK-LIVE-COMDAT-NOT: Name: .myinit_array.aaa
 # CHECK-LIVE-COMDAT-NOT: Name: .mybss.aaa
 # CHECK-LIVE-COMDAT-NOT: Name: .mynote.aaa
 # CHECK-LIVE-COMDAT: Name: .myanote.bbb
@@ -76,9 +73,6 @@ anote_aaa:
 aaa:
 .byte 0
 
-.section .myinit_array.aaa,"awG", at init_array,aaa
-.byte 0
-
 .section .mybss.aaa,"awG", at nobits,aaa
 bss_aaa:
 .byte 0