[ELF] Support input section description .gnu.version* in /DISCARD/

Linux powerpc discards `*(.gnu.version*)` (arch/powerpc/kernel/vmlinux.lds.S)
to suppress --orphan-handling=warn warnings in the -pie output `.tmp_vmlinux1`

The support is simple. Just add isLive() to:

1) Fix an assertion in SectionBase::getPartition() called by VersionTableSection::isNeeded().
2) Suppress DT_VERSYM, DT_VERDEF, DT_VERNEED and DT_VERNEEDNUM, if the relevant section is discarded.

Reviewed By: grimar

Differential Revision: https://reviews.llvm.org/D71819

1 files changed, 47 insertions, 0 deletions

diff --git a/lld/test/ELF/linkerscript/discard-gnu-version.s b/lld/test/ELF/linkerscript/discard-gnu-version.s
new file mode 100644
index 00000000000..7a40236feaa
--- /dev/null
+++ b/lld/test/ELF/linkerscript/discard-gnu-version.s
@@ -0,0 +1,47 @@
+# REQUIRES: x86
+# RUN: echo '.globl f; f:' | llvm-mc -filetype=obj -triple=x86_64 - -o %t1.o
+# RUN: echo 'v1 { f; };' > %t1.ver
+# RUN: ld.lld -shared --version-script %t1.ver %t1.o -o %t1.so
+
+# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t.o
+# RUN: echo 'v1 { foo; };' > %t.ver
+# RUN: ld.lld -shared --version-script %t.ver %t.o %t1.so -o %t.so
+# RUN: llvm-readelf -S -d %t.so | FileCheck --check-prefixes=SYM,DEF,NEED %s
+
+# SYM:  .gnu.version
+# DEF:  .gnu.version_d
+# NEED: .gnu.version_r
+
+# SYM:  (VERSYM)
+# DEF:  (VERDEF)
+# DEF:  (VERDEFNUM)
+# NEED: (VERNEED)
+# NEED: (VERNEEDNUM)
+
+## Discard all of .gnu.version*
+# RUN: echo 'SECTIONS { /DISCARD/ : { *(.gnu.version*) } }' > %t.script
+# RUN: ld.lld -shared --version-script %t.ver -T %t.script %t.o %t1.so -o %t.so
+# RUN: llvm-readelf -S -d %t.so | FileCheck /dev/null \
+# RUN:   --implicit-check-not='(VER' --implicit-check-not=.gnu.version
+
+## Discard .gnu.version
+# RUN: echo 'SECTIONS { /DISCARD/ : { *(.gnu.version) } }' > %t.noversym.script
+# RUN: ld.lld -shared --version-script %t.ver -T %t.noversym.script %t.o %t1.so -o %t.noversym.so
+# RUN: llvm-readelf -S -d %t.noversym.so | FileCheck --check-prefixes=DEF,NEED %s \
+# RUN:   --implicit-check-not='(VER' --implicit-check-not=.gnu.version
+
+## Discard .gnu.version_d
+# RUN: echo 'SECTIONS { /DISCARD/ : { *(.gnu.version_d) } }' > %t.noverdef.script
+# RUN: ld.lld -shared --version-script %t.ver -T %t.noverdef.script %t.o %t1.so -o %t.noverdef.so
+# RUN: llvm-readelf -S -d %t.noverdef.so | FileCheck --check-prefixes=SYM,NEED %s \
+# RUN:   --implicit-check-not='(VER' --implicit-check-not=.gnu.version
+
+## Discard .gnu.version_r
+# RUN: echo 'SECTIONS { /DISCARD/ : { *(.gnu.version_r) } }' > %t.noverneed.script
+# RUN: ld.lld -shared --version-script %t.ver -T %t.noverneed.script %t.o %t1.so -o %t.noverneed.so
+# RUN: llvm-readelf -S -d %t.noverneed.so | FileCheck --check-prefixes=SYM,DEF %s \
+# RUN:   --implicit-check-not='(VER' --implicit-check-not=.gnu.version
+
+.globl foo
+foo:
+  call f@plt