[lld] r359565 - [LLD][ELF] /DISCARD/ output sections should not be orphans

[Andrew Ng via llvm-commits]

Author: anng
Date: Tue Apr 30 07:31:22 2019
New Revision: 359565

URL: http://llvm.org/viewvc/llvm-project?rev=359565&view=rev
Log:
[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

Added:
    lld/trunk/test/ELF/linkerscript/discard-phdr.s
Modified:
    lld/trunk/ELF/LinkerScript.cpp

Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=359565&r1=359564&r2=359565&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Tue Apr 30 07:31:22 2019
@@ -482,6 +482,7 @@ void LinkerScript::processSectionCommand
       if (Sec->Name == "/DISCARD/") {
         discard(V);
         Sec->SectionCommands.clear();
+        Sec->SectionIndex = 0; // Not an orphan.
         continue;
       }
 

Added: lld/trunk/test/ELF/linkerscript/discard-phdr.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/discard-phdr.s?rev=359565&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/discard-phdr.s (added)
+++ lld/trunk/test/ELF/linkerscript/discard-phdr.s Tue Apr 30 07:31:22 2019
@@ -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