[PATCH] D61186: [LLD][ELF] /DISCARD/ output sections should not be orphans

[Andrew Ng via Phabricator via llvm-commits]

andrewng created this revision.
andrewng added reviewers: ruiu, grimar.
Herald added subscribers: MaskRay, arichardson, emaste.
Herald added a reviewer: espindola.

/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.


https://reviews.llvm.org/D61186

Files:
  ELF/LinkerScript.cpp
  test/ELF/linkerscript/discard-phdr.s


Index: test/ELF/linkerscript/discard-phdr.s
===================================================================
--- /dev/null
+++ test/ELF/linkerscript/discard-phdr.s
@@ -0,0 +1,44 @@
+# 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:   data PT_LOAD FLAGS(0x4 | 0x2); \
+# RUN: } \
+# RUN: SECTIONS { \
+# RUN:  .text : { *(.text) } :exec \
+# RUN:  .data : { *(.data) } :data \
+# RUN:  .foo : { *(.foo) } \
+# RUN:  .bar : { *(.bar) } \
+# RUN:  .baz : { *(.baz) } \
+# RUN:  /DISCARD/ : { *(.comment) } :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: .data
+# CHECK-NEXT: .foo
+# CHECK-NEXT: .bar
+# CHECK-NEXT: .baz
+
+# CHECK: Segment Sections
+# CHECK-NEXT: .text
+# CHECK-NEXT: .data .foo .bar .baz
+
+.section .text,"ax"
+ ret
+
+.section .data,"aw"
+ .byte 0
+
+.section .foo,"aw"
+ .byte 0
+
+.section .bar,"a"
+ .byte 0
+
+.section .baz,"aw"
+ .byte 0
Index: ELF/LinkerScript.cpp
===================================================================
--- ELF/LinkerScript.cpp
+++ ELF/LinkerScript.cpp
@@ -482,6 +482,7 @@
       if (Sec->Name == "/DISCARD/") {
         discard(V);
         Sec->SectionCommands.clear();
+        Sec->SectionIndex = 0; // Not an orphan.
         continue;
       }
 


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