[LLD][ELF] /DISCARD/ output sections should not be orphans

/DISCARD/ output sections were being treated as orphans. As a result, if a /DISCARD/ output section has been assigned a PHDR, it could cause incorrect assignment of sections to segments. Differential Revision: https://reviews.llvm.org/D61186 llvm-svn: 359565
llvm · Apr 30, 2019 · 24896d3 · 24896d3
1 parent 5b54006
commit 24896d3
Showing 2 changed files with 37 additions and 0 deletions.
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
@@ -482,6 +482,7 @@ void LinkerScript::processSectionCommands() {
       if (Sec->Name == "/DISCARD/") {
         discard(V);
         Sec->SectionCommands.clear();
+        Sec->SectionIndex = 0; // Not an orphan.
         continue;
       }
 

diff --git a/lld/test/ELF/linkerscript/discard-phdr.s b/lld/test/ELF/linkerscript/discard-phdr.s
@@ -0,0 +1,36 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "PHDRS { \
+# RUN:   exec PT_LOAD FLAGS(0x4 | 0x1); \
+# RUN: } \
+# RUN: SECTIONS { \
+# RUN:  .text : { *(.text) } :exec \
+# RUN:  .foo : { *(.foo) } \
+# RUN:  .bar : { *(.bar) } \
+# RUN:  /DISCARD/ : { *(.discard) } :NONE \
+# RUN: }" > %t.script
+# RUN: ld.lld -o %t --script %t.script %t.o
+# RUN: llvm-readelf -S -l %t | FileCheck %s
+
+## Check that /DISCARD/ does not interfere with the assignment of segments to
+## sections.
+
+# CHECK: Section Headers
+# CHECK: .text
+# CHECK-NEXT: .foo
+# CHECK-NEXT: .bar
+
+# CHECK: Segment Sections
+# CHECK-NEXT: .text .foo .bar
+
+.section .text,"ax"
+ ret
+
+.section .foo,"a"
+ .byte 0
+
+.section .bar,"ax"
+ ret
+
+.section .discard
+ .byte 0