4d9020ca0b
GNU ld's relocatable linking behaviors:
* Sections with the `SHF_GROUP` flag are handled like sections matched
by the `--unique=pattern` option. They are processed like orphan
sections and ignored by input section descriptions.
* Section groups' (usually named `.group`) content is updated as the
section indexes are updated. Section groups can be discarded with
`/DISCARD/ : { *(.group) }`.
`-r --force-group-allocation` discards section groups and allows
sections with the `SHF_GROUP` flag to be matched like normal sections.
If two section group members are placed into the same output section,
their relocation sections (if present) are combined as well.
This behavior can be useful when -r output is used as a pseudo shared
object (e.g., FreeBSD's amd64 kernel modules, CHERIoT compartments).
This patch implements --force-group-allocation:
* Input SHT_GROUP sections are discarded.
* Input sections do not get the SHF_GROUP flag, so `addInputSec`
will combine relocation sections if their relocated section group
members are combined.
The default behavior is:
* Input SHT_GROUP sections are retained.
* Input SHF_GROUP sections can be matched (unlike GNU ld)
* Input SHF_GROUP sections keep the SHF_GROUP flag, so `addInputSec`
will create different OutputDesc copies.
GNU ld provides the `FORCE_GROUP_ALLOCATION` command, which is not
implemented.
Pull Request: https://github.com/llvm/llvm-project/pull/94704
93 lines
4.5 KiB
ArmAsm
93 lines
4.5 KiB
ArmAsm
# REQUIRES: x86
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## Test that SHT_GROUP sections are retained in relocatable output. The content
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## may be rewritten because group members may change their indices. Additionally,
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## group member may be combined or discarded (e.g. /DISCARD/ or --gc-sections).
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# RUN: rm -rf %t && split-file %s %t && cd %t
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# RUN: llvm-mc -filetype=obj -triple=x86_64 a.s -o a.o
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# RUN: ld.lld -r a.o a.o -o a.ro
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# RUN: llvm-readelf -g -S a.ro | FileCheck %s
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# CHECK: Name Type Address Off Size ES Flg Lk Inf Al
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# CHECK: .group GROUP 0000000000000000 {{.*}} 00001c 04 [[#]] [[#]] 4
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# CHECK-NEXT: .rodata.bar PROGBITS 0000000000000000 {{.*}} 000001 00 AG 0 0 1
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# CHECK-NEXT: .rodata.foo PROGBITS 0000000000000000 {{.*}} 000001 00 AG 0 0 1
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# CHECK-NEXT: .text.bar PROGBITS 0000000000000000 {{.*}} 000008 00 AXG 0 0 1
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# CHECK-NEXT: .rela.text.bar RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# CHECK-NEXT: .text.foo PROGBITS 0000000000000000 {{.*}} 000008 00 AXG [[#]] [[#]] 1
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# CHECK-NEXT: .rela.text.foo RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# CHECK-NEXT: .note.GNU-stack
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# CHECK: COMDAT group section [{{.*}}] `.group' [abc] contains 6 sections:
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# CHECK-NEXT: Name
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# CHECK-NEXT: .rodata.bar
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# CHECK-NEXT: .rodata.foo
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# CHECK-NEXT: .text.bar
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# CHECK-NEXT: .rela.text.bar
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# CHECK-NEXT: .text.foo
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# CHECK-NEXT: .rela.text.foo
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## Rewrite SHT_GROUP content if some members are combined.
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# RUN: echo 'SECTIONS { .rodata : {*(.rodata.*)} .text : {*(.text.*)} }' > combine.lds
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# RUN: ld.lld -r -T combine.lds a.o a.o -o combine.ro
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# RUN: llvm-readelf -g -S combine.ro | FileCheck %s --check-prefix=COMBINE
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# COMBINE: Name Type Address Off Size ES Flg Lk Inf Al
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# COMBINE: .rodata PROGBITS 0000000000000000 {{.*}} 000002 00 AG 0 0 1
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# COMBINE-NEXT: .text PROGBITS 0000000000000000 {{.*}} 000010 00 AXG 0 0 4
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# COMBINE-NEXT: .group GROUP 0000000000000000 {{.*}} 000014 04 [[#]] [[#]] 4
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# COMBINE-NEXT: .rela.text RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# COMBINE-NEXT: .rela.text RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# COMBINE-NEXT: .note.GNU-stack
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# COMBINE: COMDAT group section [{{.*}}] `.group' [abc] contains 4 sections:
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# COMBINE-NEXT: Name
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# COMBINE-NEXT: .rodata
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# COMBINE-NEXT: .text
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# COMBINE-NEXT: .rela.text
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# COMBINE-NEXT: .rela.text
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## If --force-group-allocation is specified, discard .group and combine .rela.* if their relocated sections are combined.
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# RUN: ld.lld -r -T combine.lds a.o a.o --force-group-allocation -o combine-a.ro
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# RUN: llvm-readelf -g -S combine-a.ro | FileCheck %s --check-prefix=COMBINE-A
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# COMBINE-A: Name Type Address Off Size ES Flg Lk Inf Al
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# COMBINE-A: .rodata PROGBITS 0000000000000000 {{.*}} 000002 00 A 0 0 1
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# COMBINE-A-NEXT: .text PROGBITS 0000000000000000 {{.*}} 000010 00 AX 0 0 4
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# COMBINE-A-NEXT: .rela.text RELA 0000000000000000 {{.*}} 000030 18 I [[#]] [[#]] 8
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# COMBINE-A-NEXT: .note.GNU-stack
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# RUN: echo 'SECTIONS { /DISCARD/ : {*(.rodata.*)} }' > discard-rodata.lds
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# RUN: ld.lld -r -T discard-rodata.lds a.o a.o -o discard-rodata.ro
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# RUN: llvm-readelf -g -S discard-rodata.ro | FileCheck %s --check-prefix=NO-RODATA
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## Handle discarded group members.
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# NO-RODATA: Name Type Address Off Size ES Flg Lk Inf Al
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# NO-RODATA: .group GROUP 0000000000000000 {{.*}} 000014 04 [[#]] [[#]] 4
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# NO-RODATA-NEXT: .text.bar PROGBITS 0000000000000000 {{.*}} 000008 00 AXG 0 0 1
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# NO-RODATA-NEXT: .rela.text.bar RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# NO-RODATA-NEXT: .text.foo PROGBITS 0000000000000000 {{.*}} 000008 00 AXG [[#]] [[#]] 1
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# NO-RODATA-NEXT: .rela.text.foo RELA 0000000000000000 {{.*}} 000018 18 IG [[#]] [[#]] 8
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# NO-RODATA-NEXT: .note.GNU-stack
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# NO-RODATA: COMDAT group section [{{.*}}] `.group' [abc] contains 4 sections:
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# NO-RODATA-NEXT: Name
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# NO-RODATA-NEXT: .text.bar
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# NO-RODATA-NEXT: .rela.text.bar
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# NO-RODATA-NEXT: .text.foo
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# NO-RODATA-NEXT: .rela.text.foo
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#--- a.s
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.weak abc
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abc:
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.section .rodata.bar,"aG",@progbits,abc,comdat
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.byte 42
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.section .rodata.foo,"aG",@progbits,abc,comdat
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.byte 42
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.section .text.bar,"axG",@progbits,abc,comdat
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.quad abc
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.section .text.foo,"axG",@progbits,abc,comdat
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.quad abc
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