remove -nostdlib from libc.so link command
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Per https://reviews.llvm.org/D156205 (which we're planning to backport to LLVM 17 and pull into `wasi-sdk`), we want to link crt1-reactor.o into libc.so so it exports `_initialize` instead of `__wasm_call_ctors`. Signed-off-by: Joel Dice <[email protected]>
abrown
approved these changes
Oct 6, 2023
sbc100
reviewed
Oct 6, 2023
Makefile
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| @@ -506,7 +506,7 @@ PIC_OBJS = \ | |||
| # to CC. This is a workaround for a Windows command line size limitation. See | |||
| # the `%.a` rule below for details. | |||
| $(SYSROOT_LIB)/%.so: $(OBJDIR)/%.so.a $(BUILTINS_LIB) | |||
| $(CC) -nostdlib -shared -o $@ -Wl,--whole-archive $< -Wl,--no-whole-archive $(BUILTINS_LIB) | |||
| $(CC) -shared -o $@ -Wl,--whole-archive $< -Wl,--no-whole-archive $(BUILTINS_LIB) | |||
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Do we want -nolibc perhaps? (We wouldn't want the static version of libc linked into the dynamic version.. but I'm not sure if that would actually happen..).
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(Can you see of -lc is added to the link line.. I don't think we would want that when building libc itself).
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Looks like -lc does show up:
"/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/wasm-ld" -m wasm32 -L/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi/crt1-reactor.o --entry _initialize -shared --whole-archive build/wasm32-wasi/libc.so.a --no-whole-archive /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -lc /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -o /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.so
There's no obvious ill effect, but I can go ahead and add -nolibc.
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Apparently I'm doing it wrong:
$ /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/clang -v -nolibc -shared -o /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.so -Wl,--whole-archive build/wasm32-wasi/libc.so.a -Wl,--no-whole-archive /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a
clang version 17.0.1 (https://github.com/dicej/llvm-project e19b7dc36bc047b9eb72078d034596be766da350)
Target: wasm32-unknown-wasi
Thread model: posix
InstalledDir: /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin
clang: warning: argument unused during compilation: '-nolibc' [-Wunused-command-line-argument]
"/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/wasm-ld" -m wasm32 -L/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi/crt1-reactor.o --entry _initialize -shared --whole-archive build/wasm32-wasi/libc.so.a --no-whole-archive /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -lc /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -o /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.so
wasm-ld: warning: creating shared libraries, with -shared, is not yet stable
$ /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/clang -v -Wl,-nolibc -shared -o /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.so -Wl,--whole-archive build/wasm32-wasi/libc.so.a -Wl,--no-whole-archive /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a
clang version 17.0.1 (https://github.com/dicej/llvm-project e19b7dc36bc047b9eb72078d034596be766da350)
Target: wasm32-unknown-wasi
Thread model: posix
InstalledDir: /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin
"/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/wasm-ld" -m wasm32 -L/Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/bin/../share/wasi-sysroot/lib/wasm32-wasi/crt1-reactor.o --entry _initialize -shared -nolibc --whole-archive build/wasm32-wasi/libc.so.a --no-whole-archive /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -lc /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/lib/clang/17/lib/wasi/libclang_rt.builtins-wasm32.a -o /Users/dicej/p/component-linking-demo/wasi-sdk/build/install/opt/wasi-sdk/share/wasi-sysroot/lib/wasm32-wasi/libc.so
wasm-ld: error: unknown argument: -nolibc
clang: error: linker command failed with exit code 1 (use -v to see invocation)
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Oh.. maybe clang doesn't support that flag?
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Yeah, -nodefaultlibs seems to do the trick. I really wish clang --help would list all the options it supports.
This ensures that `-lc` is not passed to `wasm-ld`. Signed-off-by: Joel Dice <[email protected]>
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Per https://reviews.llvm.org/D156205 (which we're planning to backport to LLVM 17 and pull into
wasi-sdk), we want to link crt1-reactor.o into libc.so so it exports_initializeinstead of__wasm_call_ctors.