Summary:
This ensures that object files will continue to validate as
WebAssembly modules in the presence of bulk memory operations. Engines
that don't support bulk memory operations will not recognize the
DataCount section and will report validation errors, but that's ok
because object files aren't supposed to be run directly anyway.
Reviewers: aheejin, dschuff, sbc100
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60623
llvm-svn: 358315
Summary:
It does not currently make sense to use WebAssembly features in some functions
but not others, so this CL adds an IR pass that takes the union of all used
feature sets and applies it to each function in the module. This allows us to
prevent atomics from being lowered away if some function has opted in to using
them. When atomics is not enabled anywhere, we detect whether there exists any
atomic operations or thread local storage that would be stripped and disallow
linking with objects that contain atomics if and only if atomics or tls are
stripped. When atomics is enabled, mark it as used but do not require it of
other objects in the link. These changes allow libraries that do not use atomics
to be built once and linked into both single-threaded and multithreaded
binaries.
Reviewers: aheejin, sbc100, dschuff
Subscribers: jgravelle-google, hiraditya, sunfish, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59625
llvm-svn: 357226
Summary:
Implements a new target features section in assembly and object files
that records what features are used, required, and disallowed in
WebAssembly objects. The linker uses this information to ensure that
all objects participating in a link are feature-compatible and records
the set of used features in the output binary for use by optimizers
and other tools later in the toolchain.
The "atomics" feature is always required or disallowed to prevent
linking code with stripped atomics into multithreaded binaries. Other
features are marked used if they are enabled globally or on any
function in a module.
Future CLs will add linker flags for ignoring feature compatibility
checks and for specifying the set of allowed features, implement using
the presence of the "atomics" feature to control the type of memory
and segments in the linked binary, and add front-end flags for
relaxing the linkage policy for atomics.
Reviewers: aheejin, sbc100, dschuff
Subscribers: jgravelle-google, hiraditya, sunfish, mgrang, jfb, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59173
llvm-svn: 356610
Summary:
In the clang UI, replaces -mthread-model posix with -matomics as the
source of truth on threading. In the backend, replaces
-thread-model=posix with the atomics target feature, which is now
collected on the WebAssemblyTargetMachine along with all other used
features. These collected features will also be used to emit the
target features section in the future.
The default configuration for the backend is thread-model=posix and no
atomics, which was previously an invalid configuration. This change
makes the default valid because the thread model is ignored.
A side effect of this change is that objects are never emitted with
passive segments. It will instead be up to the linker to decide
whether sections should be active or passive based on whether atomics
are used in the final link.
Reviewers: aheejin, sbc100, dschuff
Subscribers: mehdi_amini, jgravelle-google, hiraditya, sunfish, steven_wu, dexonsmith, rupprecht, jfb, jdoerfert, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D58742
llvm-svn: 355112
Summary:
Rename MemoryIndex to InitFlags and implement logic for determining
data segment layout in ObjectYAML and MC. Also adds a "passive" flag
for the .section assembler directive although this cannot be assembled
yet because the assembler does not support data sections.
Reviewers: sbc100, aardappel, aheejin, dschuff
Subscribers: jgravelle-google, hiraditya, sunfish, rupprecht, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D57938
llvm-svn: 354397
Summary: The final -wasm component has been the default for some time now.
Subscribers: jfb, dschuff, jgravelle-google, eraman, aheejin, JDevlieghere, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D46342
llvm-svn: 332007
Neither the linker nor the runtime need this information
anymore. We were originally using this to model BSS size
but the plan is now to use the segment metadata to allow
for BSS segments.
Differential Revision: https://reviews.llvm.org/D41366
llvm-svn: 326267
This is combination of two patches by Nicholas Wilson:
1. https://reviews.llvm.org/D41954
2. https://reviews.llvm.org/D42495
Along with a few local modifications:
- One change I made was to add the UNDEFINED bit to the binary format
to avoid the extra byte used when writing data symbols. Although this
bit is redundant for other symbols types (i.e. undefined can be
implied if a function or global is a wasm import)
- I prefer to be explicit and consistent and not have derived flags.
- Some field renaming.
- Some reverting of unrelated minor changes.
- No test output differences.
Differential Revision: https://reviews.llvm.org/D43147
llvm-svn: 325860
This matches the CodeGen tests and makes it a little easy
to run these from the command line manually.
Differential Revision: https://reviews.llvm.org/D42440
llvm-svn: 323275
These indexes are useful because they are not always zero based and
functions and globals are referenced elsewhere by their index.
This matches what we already do for the type index space.
Differential Revision: https://reviews.llvm.org/D41877
llvm-svn: 322121
Add adds support for naming data segments. This is useful
useful linkers so that they can merge similar sections.
Differential Revision: https://reviews.llvm.org/D37886
llvm-svn: 313795
Add adds support for naming data segments. This is useful
useful linkers so that they can merge similar sections.
Differential Revision: https://reviews.llvm.org/D37886
llvm-svn: 313692
This means that we can honor -fdata-sections rather than
always creating a segment for each symbol.
It also allows for a followup change to add .init_array and friends.
Differential Revision: https://reviews.llvm.org/D37876
llvm-svn: 313395
Thomas Lively