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[zig cc/elf] does not pass "-r" to ld.lld #11683

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motiejus opened this issue May 20, 2022 · 4 comments · Fixed by #15201
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[zig cc/elf] does not pass "-r" to ld.lld #11683

motiejus opened this issue May 20, 2022 · 4 comments · Fixed by #15201
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bug Observed behavior contradicts documented or intended behavior zig cc Zig as a drop-in C compiler feature
Milestone
0.11.0

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@motiejus
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motiejus commented May 20, 2022 •
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Zig Version

0.10.0-dev.2252+a4369918b

Steps to Reproduce

Compile an object file and pass -r to it:

zig-cc -fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build1086133851=/tmp/go-build -gno-record-gcc-switches -nostdlib -r -o /tmp/elf-zigcc/ldr.syso /tmp/elf-zigcc/x0.o /tmp/elf-zigcc/x1.o

Expected Behavior

The underlying ld.lld command also has -r

Actual Behavior

The linker line is missing -r:

ld.lld -error-limit=0 -O0 -z stack-size=16777216 --eh-frame-hdr -m elf_x86_64 -static -o /home/motiejus/.cache/zig/o/fecbc069c368f18f63f7f97d81ed0279/ldr.syso -L /usr/local/lib64 -L /usr/local/lib -L /usr/lib/x86_64-linux-gnu -L /lib64 -L /lib -L /usr/lib64 -L /usr/lib -L /lib/x86_64-linux-gnu /tmp/elf-zigcc/x0.o /tmp/elf-zigcc/x1.o /home/motiejus/.cache/zig/o/a400e3bbd0b20e8df86f8cb4900e42e6/libc.a /home/motiejus/.cache/zig/o/af8550d2991476a4c76b9fa2e199da85/libcompiler_rt.a --as-needed

This causes a Golang test cmd/link/elf_test.go:TestMinusRSymsWithSameName to fail when using zig cc as the compiler.

To reproduce: this will build the Go sdk with Zig and attempt to run it's cmd/link tests:

git clone https://github.com/golang/go
cd go/src
echo -e '#!/bin/sh\nexec zig cc -Wl,--no-gc-sections "$@"' > zig-cc; chmod a+x zig-cc
CC=$PWD/zig-cc sh -c "./make.bash && ./run.bash -run cmd/link"
<...>
##### Testing packages.
--- FAIL: TestMinusRSymsWithSameName (1.02s)
    elf_test.go:166: /home/motiejus/code/go/src/zig-cc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build777708704=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName4069257377/001/x0.o /tmp/TestMinusRSymsWithSameName4069257377/001/x0.c
    elf_test.go:166: /home/motiejus/code/go/src/zig-cc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build777708704=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName4069257377/001/x1.o /tmp/TestMinusRSymsWithSameName4069257377/001/x1.c
    elf_test.go:174: /home/motiejus/code/go/src/zig-cc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build777708704=/tmp/go-build -gno-record-gcc-switches] -nostdlib -r -o /tmp/TestMinusRSymsWithSameName4069257377/001/ldr.syso [/tmp/TestMinusRSymsWithSameName4069257377/001/x0.o /tmp/TestMinusRSymsWithSameName4069257377/001/x1.o]
    elf_test.go:194: /home/motiejus/code/go/bin/go build
    elf_test.go:199: # elf_test
        loadelf: $WORK/b001/_pkg_.a(ldr.syso): elf but not elf relocatable object
    elf_test.go:200: exit status 2

If we apply #11678, this test passes.
@motiejus motiejus added the bug Observed behavior contradicts documented or intended behavior label May 20, 2022
@motiejus motiejus mentioned this issue May 20, 2022
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@motiejus
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As mentioned by @andrewrk in #11678, #7094 and #7547 are related to this.

@andrewrk andrewrk added the zig cc Zig as a drop-in C compiler feature label Jun 2, 2022
@andrewrk andrewrk added this to the 0.10.0 milestone Jun 2, 2022
@andrewrk andrewrk modified the milestones: 0.10.0, 0.10.1 Oct 12, 2022
@andrewrk andrewrk modified the milestones: 0.10.1, 0.11.0 Jan 10, 2023
@motiejus
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motiejus commented Apr 7, 2023 •
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I have been working through the Go unit tests with Zig as the C compiler. The test below is the last Go unit test that fails on Go's master1.

Steps to reproduce

$HOME/zcc

#!/bin/sh
export ZIG_GLOBAL_CACHE_DIR=/home/motiejus/.cache/zig
export ZIG_LOCAL_CACHE_DIR=/home/motiejus/.cache/zig
exec /code/zig/build/stage3/bin/zig cc "$@"

run

$ git clone https://github.com/golang/go; cd go/src
$ ./make.bash
< wait for Go to build >
$ cd cmd/link
$ CC=$HOME/zcc ../../../bin/go test -run TestMinusRSymsWithSameName$                                                                          
--- FAIL: TestMinusRSymsWithSameName (1.02s)                                                                                                                                       
    elf_test.go:164: /home/motiejus/zcc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1568376719=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName1171769842/001/x0.o /tmp/TestMinusRSymsWithSameName1171769842/001/x0.c                          
    elf_test.go:164: /home/motiejus/zcc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build15683
76719=/tmp/go-build -gno-record-gcc-switches] -c -o /tmp/TestMinusRSymsWithSameName1171769842/001/x1.o /tmp/TestMinusRSymsWithSameName1171769842/001/x1.c                          
    elf_test.go:172: /home/motiejus/zcc [-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build1568376719=/tmp/go-build -gno-record-gcc-switches] -nostdlib -r -o /tmp/TestMinusRSymsWithSameName1171769842/001/ldr.syso [/tmp/TestMinusRSymsWithSameName1171769842/001/x0.o /tmp/TestM
inusRSymsWithSameName1171769842/001/x1.o]                                                                                                                                          
    elf_test.go:192: /code/go/bin/go build                                                                                                                                         
    elf_test.go:197: # elf_test                                                                                                                                                    
        loadelf: $WORK/b001/_pkg_.a(ldr.syso): elf but not elf relocatable object                                                                                                  
    elf_test.go:198: exit status 1                                                                                                                                                 
FAIL                                                                                                                                                                               
exit status 1                                                                                                                                                                      
FAIL    cmd/link        1.025s

As we can see, the resulting syso is built with -r flag. Not 100% sure it is caused by what is registered in this ticket, but it strikes me as quite close.

Footnotes

  1. having cherry-picked https://go-review.googlesource.com/c/go/+/483035 to Go and zig cc: support reading from stdin via "-x LANG -" #14462 to Zig. ↩

andrewrk added a commit that referenced this issue Apr 7, 2023
@andrewrk
zig cc: handle the -r flag
896c3b5 
This makes -r treated the same as -c which is to output an object file.
Zig's ELF linker code already handles multiple object files into an
object file with the -r flag to LLD.

closes #11683
@andrewrk andrewrk mentioned this issue Apr 7, 2023
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@andrewrk
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andrewrk commented Apr 7, 2023

Could you give #15201 a try?

@motiejus
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motiejus commented Apr 8, 2023

Yes. It helps for that particular test. Thank you!

andrewrk added a commit that referenced this issue Apr 8, 2023
@andrewrk
zig cc: handle the -r flag
c22a30a 
This makes -r treated the same as -c which is to output an object file.
Zig's ELF linker code already handles multiple object files into an
object file with the -r flag to LLD.

closes #11683
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Labels
bug Observed behavior contradicts documented or intended behavior zig cc Zig as a drop-in C compiler feature
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Milestone
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zig cc: handle the -r flag ziglang/zig
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