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[ELF] Add test for interaction of --gc-sections and undefined references
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Authored by jhenderson on Jan 19 2018, 6:56 AM.

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Reviewers

• rafael
ruiu

Commits

rG0018ca846210: Add test for interaction of --gc-sections and undefined references
rLLD323099: Add test for interaction of --gc-sections and undefined references
rL323099: Add test for interaction of --gc-sections and undefined references

Summary

It is possible for a link to fail with an undefined reference, unless --gc-sections is specified, removing the reference in the process. This doesn't look to be tested anywhere explicitly, so I thought it useful to add a test for it to ensure the behaviour is maintained.

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Repository: rLLD LLVM Linker

Event Timeline

jhenderson created this revision.Jan 19 2018, 6:56 AM

Herald added subscribers: llvm-commits, emaste. · View Herald TranscriptJan 19 2018, 6:56 AM

LGTM

test/ELF/gc-sections-no-undef-error.s
7–8	You can write this in one line. not ld.lld %t.o -o %t 2>&1 \| FileCheck %s

This revision is now accepted and ready to land.Jan 19 2018, 2:27 PM

jhenderson added inline comments.Jan 22 2018, 2:51 AM

test/ELF/gc-sections-no-undef-error.s
7–8	Thanks Rui. I thought I'd read somewhere on the mailing lists advising against doing that for some reason, but I can't find it now, so I may be misremembering it.

Closed by commit rL323099: Add test for interaction of --gc-sections and undefined references (authored by jhenderson). · Explain WhyJan 22 2018, 3:00 AM

This revision was automatically updated to reflect the committed changes.

I thought I'd read somewhere on the mailing lists advising against doing that for some reason, but I can't find it now, so I may be misremembering it.

Not sure if it is actually discouraged, but at least in lld it's conventional.

Revision Contents

Path

Size

test/

ELF/

gc-sections-no-undef-error.s

20 lines

Diff 130613

test/ELF/gc-sections-no-undef-error.s

				# REQUIRES: x86

				# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o

				# Sanity check that the link will fail with the undefined error without
				# gc-sections.
				# RUN: not ld.lld %t.o -o %t 2> %t.err
				# RUN: FileCheck %s --input-file %t.err
				ruiuUnsubmitted Not Done Reply Inline Actions You can write this in one line. not ld.lld %t.o -o %t 2>&1 \| FileCheck %s ruiu: You can write this in one line. not ld.lld %t.o -o %t 2>&1 \| FileCheck %s
				jhendersonAuthorUnsubmitted Not Done Reply Inline Actions Thanks Rui. I thought I'd read somewhere on the mailing lists advising against doing that for some reason, but I can't find it now, so I may be misremembering it. jhenderson: Thanks Rui. I thought I'd read somewhere on the mailing lists advising against doing that for…
				# CHECK: error: undefined symbol: undefined

				# RUN: ld.lld %t.o --gc-sections -o %t

				.section .text.unused,"ax",@progbits
				unused:
				callq undefined

				.text
				.global _start
				_start:
				nop