[lld][WebAssembly] Add --unresolved-symbols=import-dynamic

This is a new mode for handling unresolved symbols that allows all
symbols to be imported in the same that they would be in the case of
`-f

[lld][WebAssembly] Add --unresolved-symbols=import-dynamic

This is a new mode for handling unresolved symbols that allows all
symbols to be imported in the same that they would be in the case of
`-fpie` or `-shared`, but generting an otherwise fixed/non-relocatable
binary.

Code linked in this way should still be compiled with `-fPIC` so that
data symbols can be resolved via imports.

This essentially allows the building of static binaries that have
dynamic imports. See:
https://github.com/emscripten-core/emscripten/issues/12682

As with other uses of the experimental dynamic linking ABI, this
behaviour will produce a warning unless run with `--experimental-pic`.

Differential Revision: https://reviews.llvm.org/D91577

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[WebAssembly] Use GeneralDynamic TLS for exception handling builtins.

These global TLS symbols are shared across all shared libraries and
therefor should not be assumed to be local to the current mo

[WebAssembly] Use GeneralDynamic TLS for exception handling builtins.

These global TLS symbols are shared across all shared libraries and
therefor should not be assumed to be local to the current module.

Also add new error in the linker when TLS relocations are used against
undefined symbols. TLS relocations are offsets into the current modules
tls data segment, and don't make sense for undefined symbols which are
modeled as global imports.

Fixes: https://github.com/emscripten-core/emscripten/issues/13398

Differential Revision: https://reviews.llvm.org/D119630

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fix comment typos to cycle bots

[lld][WebAssembly] Remove redundant check for undefined global (NFC)

Also does some refactoring.

Reviewed By: sbc100

Differential Revision: https://reviews.llvm.org/D111101

[WebAssembly] Allow import and export of TLS symbols between DSOs

We previously had a limitation that TLS variables could not
be exported (and therefore could also not be imported). This
change rem

[WebAssembly] Allow import and export of TLS symbols between DSOs

We previously had a limitation that TLS variables could not
be exported (and therefore could also not be imported). This
change removed that limitation.

Differential Revision: https://reviews.llvm.org/D108877

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[WebAssembly] Add explict TLS symbol flag

As before we maintain backwards compat with older object files
by also infering the TLS flag based on the name of the segment.

This change is was split out

[WebAssembly] Add explict TLS symbol flag

As before we maintain backwards compat with older object files
by also infering the TLS flag based on the name of the segment.

This change is was split out from https://reviews.llvm.org/D108877.

Differential Revision: https://reviews.llvm.org/D109426

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[lld][WebAssembly] Error on import of TLS symbols in shared libraries

In https://reviews.llvm.org/D102044 we made exporting a TLS symbol
into an error, but we also want to error on import.

See http

[lld][WebAssembly] Error on import of TLS symbols in shared libraries

In https://reviews.llvm.org/D102044 we made exporting a TLS symbol
into an error, but we also want to error on import.

See https://github.com/emscripten-core/emscripten/issues/14461

Differential Revision: https://reviews.llvm.org/D106385

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[WebAssembly] Support R_WASM_MEMORY_ADDR_TLS_SLEB64 for wasm64

Also fixed TLS tests swapping addr & value in store op
Differential Revision: https://reviews.llvm.org/D106096

[lld][WebAssembly] Add new `--import-undefined` option

This change revisits https://reviews.llvm.org/D79248 which originally
added support for the --unresolved-symbols flag.

At the time I thought i

[lld][WebAssembly] Add new `--import-undefined` option

This change revisits https://reviews.llvm.org/D79248 which originally
added support for the --unresolved-symbols flag.

At the time I thought it would make sense to add a third option to this
flag called `import-functions` but it turns out (as was suspects by on
the reviewers IIRC) that this option can be authoganal.

Instead I've added a new option called `--import-undefined` that only
operates on symbols that can be imported (for example, function symbols
can always be imported as opposed to data symbols we can only be
imported when compiling with PIC).

This option gives us the full expresivitiy that emscripten needs to be
able allow reporting of undefined data symbols as well as the option to
disable that.

This change does remove the `--unresolved-symbols=import-functions`
option, which is been in the codebase now for about a year but I would
be extremely surprised if anyone was using it.

Differential Revision: https://reviews.llvm.org/D103290

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[lld][WebAssembly] Fix for PIC output + TLS + non-shared-memory

Prior to this change build with `-shared/-pie` and using TLS (but
without -shared-memory) would hit this assert:

"Currenly only a s

[lld][WebAssembly] Fix for PIC output + TLS + non-shared-memory

Prior to this change build with `-shared/-pie` and using TLS (but
without -shared-memory) would hit this assert:

"Currenly only a single data segment is supported in PIC mode"

This is because we were not including TLS data when merging data
segments. However, when we build without shared-memory (i.e. without
threads) we effectively lower away TLS into a normal active data
segment.. so we were ending up with two active data segments: the merged
data, and the lowered TLS data.

To fix this problem we can instead avoid combining data segments at
all when running in shared memory mode (because in this case all
segment initialization is passive). And then in non-shared memory
mode we know that TLS has been lowered and therefore we can can
and should combine all segments.

So with this new behavior we have two different modes:

1. With shared memory / mutli-threaded: Never combine data segments
since it is not necessary. (All data segments as passive already).

2. Wihout shared memory / single-threaded: Combine *all* data segments
since we treat TLS as normal data. (We end up with a single
active data segment).

Differential Revision: https://reviews.llvm.org/D102937

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[WebAssembly] Fix PIC/GOT codegen for wasm64

__table_base is know 64-bit, since in LLVM it represents a function pointer offset
__table_base32 is a copy in wasm32 for use in elem init expr, since no

[WebAssembly] Fix PIC/GOT codegen for wasm64

__table_base is know 64-bit, since in LLVM it represents a function pointer offset
__table_base32 is a copy in wasm32 for use in elem init expr, since no truncation may be used there.
New reloc R_WASM_TABLE_INDEX_REL_SLEB64 added

Differential Revision: https://reviews.llvm.org/D101784

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[lld][WebAssembly] Disallow exporting of TLS symbols

Cross module TLS is currently not supported by our ABI. This
change makes explicitly exporting a TLS symbol into an error
and prevents implicit

[lld][WebAssembly] Disallow exporting of TLS symbols

Cross module TLS is currently not supported by our ABI. This
change makes explicitly exporting a TLS symbol into an error
and prevents implicit exporting (via --export-all).

See https://github.com/emscripten-core/emscripten/issues/14120

Differential Revision: https://reviews.llvm.org/D102044

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[lld][WebAssembly] Fix crash with `-pie` without `--allow-undefined`

`shouldImport` was not returning true in PIC mode even though out
assumption elsewhere (in Relocations.cpp:scanRelocations) is th

[lld][WebAssembly] Fix crash with `-pie` without `--allow-undefined`

`shouldImport` was not returning true in PIC mode even though out
assumption elsewhere (in Relocations.cpp:scanRelocations) is that we
don't report undefined symbols in PIC mode today. This was resulting
functions that were undefined and but also not imported which hits an
assert later on that all functions have valid indexes.

Differential Revision: https://reviews.llvm.org/D101716

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[lld][WebAssembly] Ensure stub symbols always get address 0

Without this extra flag we can't distingish between stub functions and
functions that happen to have address 0 (relative to __table_base).

[lld][WebAssembly] Ensure stub symbols always get address 0

Without this extra flag we can't distingish between stub functions and
functions that happen to have address 0 (relative to __table_base).

Adding this flag bit the base symbol class actually avoids growing the
SymbolUnion struct which would not be true if we added it to the
FunctionSymbol subclass (due to bitbacking).

The previous approach of setting it's table index to zero worked for
normal static relocations but not for `-fPIC` code.

See https://github.com/emscripten-core/emscripten/issues/12819

Differential Revision: https://reviews.llvm.org/D92038

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[lld][WebAssembly] Implement --unresolved-symbols

This is a more full featured version of ``--allow-undefined``.
The semantics of the different methods are as follows:

report-all:

Report all un

[lld][WebAssembly] Implement --unresolved-symbols

This is a more full featured version of ``--allow-undefined``.
The semantics of the different methods are as follows:

report-all:

Report all unresolved symbols. This is the default. Normally the
linker will generate an error message for each reported unresolved
symbol but the option ``--warn-unresolved-symbols`` can change this
to a warning.

ignore-all:

Resolve all undefined symbols to zero. For data and function
addresses this is trivial. For direct function calls, the linker
will generate a trapping stub function in place of the undefined
function.

import-functions:

Generate WebAssembly imports for any undefined functions. Undefined
data symbols are resolved to zero as in `ignore-all`. This
corresponds to the legacy ``--allow-undefined`` flag.

The plan is to followup with a new mode called `import-dynamic` which
allows for statically linked binaries to refer to both data and
functions symbols from the embedder.

Differential Revision: https://reviews.llvm.org/D79248

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[WebAssembly] Add new relocation type for TLS data symbols

These relocations represent offsets from the __tls_base symbol.

Previously we were just using normal MEMORY_ADDR relocations and relying
o

[WebAssembly] Add new relocation type for TLS data symbols

These relocations represent offsets from the __tls_base symbol.

Previously we were just using normal MEMORY_ADDR relocations and relying
on the linker to select a segment-offset rather and absolute value in
Symbol::getVirtualAddress(). Using an explicit relocation type allows
allow us to clearly distinguish absolute from relative relocations based
on the relocation information alone.

One place this is useful is being able to reject absolute relocation in
the PIC case, but still accept TLS relocations.

Differential Revision: https://reviews.llvm.org/D91276

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[lld][WebAssembly] Add support for -Bsymbolic flag

This flag works in a similar way to the ELF linker in that it
will resolve any defined symbols to their local definition with
a shared library or -

[lld][WebAssembly] Add support for -Bsymbolic flag

This flag works in a similar way to the ELF linker in that it
will resolve any defined symbols to their local definition with
a shared library or -pie executable.

This flag has no effect on static linking.

Differential Revision: https://reviews.llvm.org/D89152

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[lld][WebAssembly] Allow globals imports via import_name/import_module

This feature already exists but was limited to function
symbols.

Differential Revision: https://reviews.llvm.org/D87666

[WebAssembly] 64-bit (function) pointer fixes.

Accounting for the fact that Wasm function indices are 32-bit, but in wasm64 we want uniform 64-bit pointers.
Includes reloc types for 64-bit table ind

[WebAssembly] 64-bit (function) pointer fixes.

Accounting for the fact that Wasm function indices are 32-bit, but in wasm64 we want uniform 64-bit pointers.
Includes reloc types for 64-bit table indices.

Differential Revision: https://reviews.llvm.org/D83729

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[WebAssembly] Adding 64-bit version of R_WASM_MEMORY_ADDR_* relocs

This adds 4 new reloc types.

A lot of code that previously assumed any memory or offset values could be contained in a uint32_t (a

[WebAssembly] Adding 64-bit version of R_WASM_MEMORY_ADDR_* relocs

This adds 4 new reloc types.

A lot of code that previously assumed any memory or offset values could be contained in a uint32_t (and often truncated results from functions returning 64-bit values) have been upgraded to uint64_t. This is not comprehensive: it is only the values that come in contact with the new relocation values and their dependents.

A new tablegen mapping was added to automatically upgrade loads/stores in the assembler, which otherwise has no way to select for these instructions (since they are indentical other than for the offset immediate). It follows a similar technique to https://reviews.llvm.org/D53307

Differential Revision: https://reviews.llvm.org/D81704

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[lld][WebAssembly] Honor --allow-undefined for data symbols too

This was originally the way this worked before before
https://reviews.llvm.org/D60882.

In retrospect it seems inconsistent that `--al

[lld][WebAssembly] Honor --allow-undefined for data symbols too

This was originally the way this worked before before
https://reviews.llvm.org/D60882.

In retrospect it seems inconsistent that `--allow-undefined` doesn't
work for all symbols. See:
https://groups.google.com/g/emscripten-discuss/c/HSRgQiIq1gI/m/Kt9oFWHiAwAJ

I'm also planning a followup change which implement the full
`--unresolved-symbols=..` flags supported by ELF linkers (both ld and
ld.lld) since it seems more standard.

Differential Revision: https://reviews.llvm.org/D79247

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[WebAssembly] Add int32 DW_OP_WASM_location variant

This to allow us to add reloctable global indices as a symbol.
Also adds R_WASM_GLOBAL_INDEX_I32 relocation type to support it.

See discussion in

[WebAssembly] Add int32 DW_OP_WASM_location variant

This to allow us to add reloctable global indices as a symbol.
Also adds R_WASM_GLOBAL_INDEX_I32 relocation type to support it.

See discussion in https://github.com/WebAssembly/debugging/issues/12

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[lld][WebAssembly] Allow symbols with explict import names to be undefined at link time.

Differential Revision: https://reviews.llvm.org/D74110

[WebAssembly] Wrap definitions in namespace lld { namespace wasm {. NFC

Similar to D68323, but for wasm.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D68759

llvm-svn: 374279

[lld][WebAssembly] Fix static linking of -fPIC code with external undefined functions

Differential Revision: https://reviews.llvm.org/D66784

llvm-svn: 372779