c0065f1182
D86142 introduced --fortran-common and defaulted it to true (matching GNU ld but deviates from gold/macOS ld64). The default state was motivated by transparently supporting some FORTRAN 77 programs (Fortran 90 deprecated common blocks). Now I think it again. I believe we made a mistake to change the default: * this is a weird and legacy rule, though the breakage is very small * --fortran-common introduced complexity to parallel symbol resolution and will slow down it * --fortran-common more likely causes issues when users mix COMMON and STB_GLOBAL definitions (see https://github.com/llvm/llvm-project/issues/48570 and https://maskray.me/blog/2022-02-06-all-about-common-symbols). I have seen several issues in our internal projects and Android. On the other hand, --no-fortran-common is safer since COMMON/STB_GLOBAL have the same semantics related to archive member extraction. Therefore I think we should switch back, not punishing the common uage. A platform wanting --fortran-common can implement ld.lld as a shell script wrapper around `lld -flavor gnu --fortran-common "$@"`. Reviewed By: ikudrin, sfertile Differential Revision: https://reviews.llvm.org/D122450
109 lines
6.4 KiB
ArmAsm
109 lines
6.4 KiB
ArmAsm
# REQUIRES: x86
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# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t1.o
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# RUN: echo '.globl foo; foo:' | llvm-mc -filetype=obj -triple=x86_64 - -o %t2.o
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# RUN: rm -f %t2.a
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# RUN: llvm-ar rcs %t2.a %t2.o
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# RUN: ld.lld -shared %t2.o -o %t2.so
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## A forward reference is accepted by a traditional Unix linker.
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# RUN: ld.lld --fatal-warnings %t1.o %t2.a -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t1.o %t2.a -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t1.o --start-lib %t2.o --end-lib -o /dev/null
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# RUN: echo 'INPUT("%t1.o" "%t2.a")' > %t1.lds
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t1.lds -o /dev/null
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## A backward reference from %t1.o to %t2.a
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## Warn unless the archive is excluded by --warn-backrefs-exclude
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# RUN: ld.lld --fatal-warnings %t2.a %t1.o -o /dev/null
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# RUN: ld.lld --warn-backrefs %t2.a %t1.o -o /dev/null 2>&1 | FileCheck %s
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# RUN: ld.lld --warn-backrefs --no-warn-backrefs %t2.a %t1.o -o /dev/null 2>&1 | count 0
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# RUN: ld.lld --warn-backrefs %t2.a '-(' %t1.o '-)' -o /dev/null 2>&1 | FileCheck %s
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# RUN: ld.lld --warn-backrefs --warn-backrefs-exclude='*3.a' %t2.a %t1.o -o /dev/null 2>&1 | FileCheck %s
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# RUN: ld.lld --fatal-warnings --warn-backrefs --warn-backrefs-exclude='*2.a(*2.o)' %t2.a %t1.o -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs --warn-backrefs-exclude '*2.a(*2.o)' \
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# RUN: --warn-backrefs-exclude not_exist %t2.a %t1.o -o /dev/null
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## Without --warn-backrefs, --warn-backrefs-exclude is ignored.
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# RUN: ld.lld --fatal-warnings --warn-backrefs-exclude=not_exist %t2.a %t1.o -o /dev/null
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## Placing the definition and the backward reference in a group can suppress the warning.
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# RUN: echo 'GROUP("%t2.a" "%t1.o")' > %t2.lds
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t2.lds -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs '-(' %t2.a %t1.o '-)' -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs --start-group %t2.a %t1.o --end-group -o /dev/null
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## A backward reference from %t1.o to %t2.a (added by %t3.lds).
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# RUN: echo 'GROUP("%t2.a")' > %t3.lds
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# RUN: ld.lld --warn-backrefs %t3.lds %t1.o -o /dev/null 2>&1 | FileCheck %s
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# RUN: ld.lld --fatal-warnings --warn-backrefs '-(' %t3.lds %t1.o '-)' -o /dev/null
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# RUN: ld.lld --fatal-warnings --warn-backrefs --warn-backrefs-exclude='*2.a(*2.o)' -o /dev/null %t3.lds %t1.o
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## If a lazy definition appears after the backward reference, don't warn.
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t3.lds %t1.o %t3.lds -o /dev/null
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# CHECK: warning: backward reference detected: foo in {{.*}}1.o refers to {{.*}}2.a
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## A backward reference from %t1.o to %t2.o
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## --warn-backrefs-exclude= applies to --start-lib covered object files.
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# RUN: ld.lld --warn-backrefs --start-lib %t2.o --end-lib %t1.o -o /dev/null 2>&1 | \
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# RUN: FileCheck --check-prefix=OBJECT %s
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# RUN: ld.lld --fatal-warnings --warn-backrefs --warn-backrefs-exclude=%/t2.o --start-lib %/t2.o --end-lib %t1.o -o /dev/null
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## If a lazy definition appears after the backward reference, don't warn.
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# RUN: ld.lld --fatal-warnings --warn-backrefs --start-lib %t2.o --end-lib %t1.o --start-lib %t2.o --end-lib -o /dev/null
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# OBJECT: warning: backward reference detected: foo in {{.*}}1.o refers to {{.*}}2.o
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## Back reference from an fetched --start-lib to a previous --start-lib.
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# RUN: ld.lld -m elf_x86_64 -u _start --warn-backrefs --start-lib %/t2.o --end-lib \
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# RUN: --start-lib %t1.o --end-lib -o /dev/null 2>&1 | FileCheck --check-prefix=OBJECT %s
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## --warn-backrefs-exclude=%/t2.o can be used for a fetched --start-lib.
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# RUN: ld.lld --fatal-warnings -m elf_x86_64 -u _start --warn-backrefs --warn-backrefs-exclude=%/t2.o --start-lib %/t2.o --end-lib --start-lib %t1.o --end-lib -o /dev/null
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## Don't warn if the definition and the backward reference are in a group.
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# RUN: echo '.globl bar; bar:' | llvm-mc -filetype=obj -triple=x86_64 - -o %t3.o
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# RUN: echo '.globl foo; foo: call bar' | llvm-mc -filetype=obj -triple=x86_64 - -o %t4.o
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t1.o --start-lib %t3.o %t4.o --end-lib -o /dev/null
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# RUN: rm -f %t34.a && llvm-ar rcS %t34.a %t3.o %t4.o
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t1.o %t34.a -o /dev/null
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## We don't report backward references to weak symbols as they can be overridden later.
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# RUN: echo '.weak foo; foo:' | llvm-mc -filetype=obj -triple=x86_64 - -o %tweak.o
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# RUN: ld.lld --fatal-warnings --warn-backrefs --start-lib %tweak.o --end-lib %t1.o %t2.o -o /dev/null
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## Check common symbols. A common sym might later be replaced by a non-common definition.
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# RUN: echo '.comm obj, 4' | llvm-mc -filetype=obj -triple=x86_64 -o %tcomm.o
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# RUN: echo '.type obj,@object; .data; .globl obj; .p2align 2; obj: .long 55; .size obj, 4' | llvm-mc -filetype=obj -triple=x86_64 -o %tstrong.o
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# RUN: echo '.globl foo; foo: movl obj(%rip), %eax' | llvm-mc -triple=x86_64 -filetype=obj -o %t5.o
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# RUN: llvm-ar rcs %tcomm.a %tcomm.o
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# RUN: llvm-ar rcs %tstrong.a %tstrong.o
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# RUN: ld.lld --warn-backrefs %tcomm.a %t1.o %t5.o 2>&1 -o /dev/null | FileCheck --check-prefix=COMM %s
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# RUN: ld.lld --fatal-warnings --fortran-common --warn-backrefs %tcomm.a %t1.o %t5.o %tstrong.a 2>&1 -o /dev/null
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# RUN: ld.lld --warn-backrefs --no-fortran-common %tcomm.a %t1.o %t5.o %tstrong.a 2>&1 -o /dev/null | FileCheck --check-prefix=COMM %s
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# COMM: ld.lld: warning: backward reference detected: obj in {{.*}}5.o refers to {{.*}}comm.a
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## If a lazy definition appears after the backward reference, don't warn.
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## A traditional Unix linker will resolve the reference to the later definition.
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t2.a %t1.o %t2.a -o /dev/null
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## lld fetches the archive while GNU ld resolves the reference to the shared definition.
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## Warn because the resolution rules are different.
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# RUN: ld.lld --warn-backrefs %t2.a %t1.o %t2.so -o /dev/null 2>&1 | FileCheck %s
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## This is a limitation. The resolution rules are different but
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## --warn-backrefs does not warn.
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# RUN: ld.lld --fatal-warnings --warn-backrefs %t2.a %t1.o %t2.so %t2.a -o /dev/null
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## In GNU linkers, -u does not make a backward reference.
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# RUN: ld.lld --fatal-warnings --warn-backrefs -u foo %t2.a %t1.o -o /dev/null
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## -u does not make a backward reference.
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# RUN: ld.lld --fatal-warnings --warn-backrefs -u foo %t2.a %t1.o -o /dev/null
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# RUN: not ld.lld --warn-backrefs-exclude='[' 2>&1 | FileCheck --check-prefix=INVALID %s
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# INVALID: error: --warn-backrefs-exclude: invalid glob pattern: [
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.globl _start, foo
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_start:
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call foo
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