In a very recent change I introduced a --no-export-default flag
but after conferring with others it seems that this feature already
exists in gnu GNU ld and lld in the form the --export-dynamic flag
which is off by default.
This change replaces export-default with export-dynamic and also
changes the default to match the traditional linker behaviour.
Now, by default, only the entry point is exported. If other symbols
are required by the embedder then --export-dynamic or --export can
be used to export all visibility hidden symbols or individual
symbols respectively.
This change touches a lot of tests that were relying on symbols
being exported by default. I imagine it will also effect many
users but do think the change is worth it match of the traditional
behaviour and flag names.
Differential Revision: https://reviews.llvm.org/D52587
llvm-svn: 343265
These option control weather or not symbols marked as visibility
default are exported in the output binary.
By default this is true, but emscripten prefers to control the
exported symbol list explicitly at link time and ignore the
symbol attributes.
Differential Revision: https://reviews.llvm.org/D52003
llvm-svn: 343034
This is a minor follow-up to https://reviews.llvm.org/D49189. On Windows, lld
used to print "lld-link.exe: error: ...". Now it just prints "lld-link: error:
...". This matches what link.exe does (it prints "LINK : ...") and makes lld's
output less dependent on the host system.
https://reviews.llvm.org/D51133
llvm-svn: 340487
LEB compression breaks debug info so we don't want to enable
it by default, even at high optimization levels.
Differential Revision: https://reviews.llvm.org/D50729
llvm-svn: 340073
--export now implies --undefined
This is really a requirement from emscripten but I think it
makes sense in general too.
Differential Revision: https://reviews.llvm.org/D50287
llvm-svn: 339047
This matches the behavior of the ELF linker where -u/--undefined
means symbols will get pulled in from archives but won't result
in link error if they are missing.
Also, don't actually great symbol table entries for the undefined
symbols, again matching more closely the ELF linker.
This also results in simplification of the code.
Differential Revision: https://reviews.llvm.org/D50279
llvm-svn: 338938
lld currently prepends the absolute path to itself to every diagnostic it
emits. This path can be longer than the diagnostic, and makes the actual error
message hard to read.
There isn't a good reason for printing this path: if you want to know which lld
you're running, pass -v to clang – chances are that if you're unsure of this,
you're not only unsure when it errors out. Some people want an indication that
the diagnostic is from the linker though, so instead print just the basename of
the linker's path.
Before:
```
$ out/bin/clang -target x86_64-unknown-linux -x c++ /dev/null -fuse-ld=lld
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: cannot open crt1.o: No such file or directory
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: cannot open crti.o: No such file or directory
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: cannot open crtbegin.o: No such file or directory
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: unable to find library -lgcc
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: unable to find library -lgcc_s
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: unable to find library -lc
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: unable to find library -lgcc
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: unable to find library -lgcc_s
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: cannot open crtend.o: No such file or directory
/Users/thakis/src/llvm-mono/out/bin/ld.lld: error: cannot open crtn.o: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```
After:
```
$ out/bin/clang -target x86_64-unknown-linux -x c++ /dev/null -fuse-ld=lld
ld.lld: error: cannot open crt1.o: No such file or directory
ld.lld: error: cannot open crti.o: No such file or directory
ld.lld: error: cannot open crtbegin.o: No such file or directory
ld.lld: error: unable to find library -lgcc
ld.lld: error: unable to find library -lgcc_s
ld.lld: error: unable to find library -lc
ld.lld: error: unable to find library -lgcc
ld.lld: error: unable to find library -lgcc_s
ld.lld: error: cannot open crtend.o: No such file or directory
ld.lld: error: cannot open crtn.o: No such file or directory
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```
https://reviews.llvm.org/D49189
llvm-svn: 337634
Function symbols that come from bitcode have not signatures.
After LTO when the real symbols are read in we need to make
sure that we set the signature on the existing symbol.
the signature-less undefined functions.
Differential Revision: https://reviews.llvm.org/D48693
llvm-svn: 335875
This caused a lot of issues on the WebAssembly waterfall.
In particular, until with the signature of `main`. We
probably want a better solution for main before we re-land.
Reverts rL335192
llvm-svn: 335355
During symbol resolution, emit warnings for function signature
mismatches. During GC, if any mismatched symbol is marked as live
then generate an error.
This means that we only error out if the mismatch is written to the
final output. i.e. if we would generate an invalid wasm file.
Differential Revision: https://reviews.llvm.org/D48394
llvm-svn: 335192
This causes all symbols to be exported in the final wasm binary
even if they were not compiled with default visibility.
This feature is useful for the emscripten toolchain that has a
corresponding EXPORT_ALL feature which allows the JS code to
interact with all C function.
Differential Revision: https://reviews.llvm.org/D47806
llvm-svn: 334157
This change adds the ability for lld to remove LEB padding from
code section. This effectively shrinks the size of the resulting
binary in proportion to the number of code relocations.
Since there will be a performance cost this is currently only active for
-O1 and above. Some toolchains may instead want to perform this
compression as a post linker step (for example running a binary through
binaryen will automatically compress these values).
I imagine we might want to make this the default in the future.
Differential Revision: https://reviews.llvm.org/D46416
llvm-svn: 332783
Since we a no longer using this function for the wasm start
section we don't actually care what its signature is.
Differential Revision: https://reviews.llvm.org/D46594
llvm-svn: 332308
Merging data segments produces smaller code sizes because each segment
has some boilerplate. Therefore, merging data segments is generally the
right approach, especially with wasm where binaries are typically
delivered over the network.
However, when analyzing wasm binaries, it can be helpful to get a
conservative picture of which functions are using which data
segments[0]. Perhaps there is a large data segment that you didn't
expect to be included in the wasm, introduced by some library you're
using, and you'd like to know which library it was. In this scenario,
merging data segments only makes the analysis worse.
Alternatively, perhaps you will remove some dead functions by-hand[1]
that can't be statically proven dead by the compiler or lld, and
removing these functions might make some data garbage collect-able, and
you'd like to run `--gc-sections` again so that this now-unused data can
be collected. If the segments were originally merged, then a single use
of the merged data segment will entrench all of the data.
[0] https://github.com/rustwasm/twiggy
[1] https://github.com/fitzgen/wasm-snip
Patch by Nick Fitzgerald!
Differential Revision: https://reviews.llvm.org/D46417
llvm-svn: 332013
This is most useful when using lld-link on a non-Win host (but it might become
useful on Windows too if lld also grows a fansi-escape-codes flag).
Also make the help for --color-diagnostic mention the valid values in ELF and
wasm, and print the flag name with two dashes in diags, since the one-dash form
is seen as a list of many one-letter flags in some contexts.
https://reviews.llvm.org/D46693
llvm-svn: 332012
Enables cleaning up confusion between which name variables are mangled
and which are unmangled, and --print-gc-sections then excersises and
tests that.
Differential Revision: https://reviews.llvm.org/D44440
llvm-svn: 330449
Since InputGlobal makes a copy of a given object, we can use a temporary
object allocated on the stack here.
Differential Revision: https://reviews.llvm.org/D43924
llvm-svn: 329337
This enables callback-style programming where the JavaScript environment
can call back into the Wasm environment using a function pointer
received from the module.
Differential Revision: https://reviews.llvm.org/D44427
llvm-svn: 328643
Previously, Config->Demangle was uninitialised (not hooked up to
commandline handling)
Differential Revision: https://reviews.llvm.org/D44301
llvm-svn: 327390
toString(T) is a stringize function for an object of type T. Each type
that has that function defined should know how to stringize itself, and
there should be one string representation of an object. Passing a
"supplemental" argument to toString() breaks that princple. We shouldn't
add a second parameter to that function.
Differential Revision: https://reviews.llvm.org/D44323
llvm-svn: 327182
This error case is described in Linking.md. The operand for call requires
generation of a synthetic stub.
Differential Revision: https://reviews.llvm.org/D44028
llvm-svn: 327151
Previously we created __wasm_call_ctors with null InputFunction, and
added the InputFunction later. Now we create the SyntheticFunction with
null body, and set the body later.
Differential Revision: https://reviews.llvm.org/D44206
llvm-svn: 327149
When a symbol is exported via --export=foo but --allow-undefined
is also specified, the symbol is now allowed to be undefined.
Previously we were special casing such symbols.
This combinations of behavior is exactly what emescripten
requires. Although we are trying hard not to allow emscripten
specific features in lld, this one makes sense.
Enforce this behavior by added this case to test/wasm/undefined.ll.
Differential Revision: https://reviews.llvm.org/D44237
llvm-svn: 326976
Previously, one function adds all types of undefined symbols. That
doesn't fit to the wasm's undefined symbol semantics well because
different types of undefined symbols are very different in wasm.
As a result, separate control flows merge in this addUndefined function
and then separate again for each type. That wasn't easy to read.
This patch separates the function into three functions. Now it is pretty
clear what we are doing for each undefined symbol type.
Differential Revision: https://reviews.llvm.org/D43697
llvm-svn: 326271
Purely a rename in preparation for adding new global symbol type.
We want to use GlobalSymbol to represent real wasm globals and
DataSymbol for pointers to things in linear memory (what ELF would
call STT_OBJECT).
This reduces the size the patch to add the explicit symbol table
which is coming soon!
Differential Revision: https://reviews.llvm.org/D43476
llvm-svn: 325645
These were duplicating (incorrectly) some of the logic for
handling conflicts, but since they are only ever added right
at the start we can assume no existing symbols.
Also rename these methods for clarity.
Differential Revision: https://reviews.llvm.org/D43252
llvm-svn: 325045
This is similar to _end (See https://linux.die.net/man/3/edata for more)
but using our own unique name since our use cases will most likely be
different and we want to keep our options open WRT to memory layout.
This change will allow is to remove the DataSize from the linking
metadata section which is currently being used by emscripten to derive
the end of the data.
Differential Revision: https://reviews.llvm.org/D42867
llvm-svn: 324443
Sam Clegg