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* [WebAssembly] Compile all TLS on Emscripten as local-execGuanzhong Chen2019-07-161-82/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Currently, on Emscripten, dynamic linking is not supported with threads. This means that if thread-local storage is used, it must be used in a statically-linked executable. Hence, local-exec is the only possible model. This diff compiles all TLS variables to use local-exec on Emscripten as a temporary measure until dynamic linking is supported with threads. The goal for this is to allow C++ types with constructors to be thread-local. Currently, when `clang` compiles a `thread_local` variable with a constructor, it generates `__tls_guard` variable: @__tls_guard = internal thread_local global i8 0, align 1 As no TLS model is specified, this is treated as general-dynamic, which we do not support (and cannot support without implementing dynamic linking support with threads in Emscripten). As a result, any C++ constructor in `thread_local` variables would not compile. By compiling all `thread_local` as local-exec, `__tls_guard` will compile and we can support C++ constructors with TLS without implementing dynamic linking with threads. Depends on D64537 Reviewers: tlively, aheejin, sbc100 Reviewed By: aheejin Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D64776 llvm-svn: 366275
* [WebAssembly] Implement thread-local storage (local-exec model)Guanzhong Chen2019-07-161-10/+75
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: Thread local variables are placed inside a `.tdata` segment. Their symbols are offsets from the start of the segment. The address of a thread local variable is computed as `__tls_base` + the offset from the start of the segment. `.tdata` segment is a passive segment and `memory.init` is used once per thread to initialize the thread local storage. `__tls_base` is a wasm global. Since each thread has its own wasm instance, it is effectively thread local. Currently, `__tls_base` must be initialized at thread startup, and so cannot be used with dynamic libraries. `__tls_base` is to be initialized with a new linker-synthesized function, `__wasm_init_tls`, which takes as an argument a block of memory to use as the storage for thread locals. It then initializes the block of memory and sets `__tls_base`. As `__wasm_init_tls` will handle the memory initialization, the memory does not have to be zeroed. To help allocating memory for thread-local storage, a new compiler intrinsic is introduced: `__builtin_wasm_tls_size()`. This instrinsic function returns the size of the thread-local storage for the current function. The expected usage is to run something like the following upon thread startup: __wasm_init_tls(malloc(__builtin_wasm_tls_size())); Reviewers: tlively, aheejin, kripken, sbc100 Subscribers: dschuff, jgravelle-google, hiraditya, sunfish, jfb, cfe-commits, llvm-commits Tags: #clang, #llvm Differential Revision: https://reviews.llvm.org/D64537 llvm-svn: 366272
* [WebAssembly] Remove uses of ThreadModelThomas Lively2019-02-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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
* [WebAssembly] Added default stack-only instruction mode for MC.Wouter van Oortmerssen2018-08-271-1/+1
| | | | | | | | | | | | | | | | | | | | | Summary: Made it convert from register to stack based instructions, and removed the registers. Fixes to related code that was expecting register based instructions. Added the correct testing flag to all tests, depending on what the format they were expecting so far. Translated one test to stack format as example: reg-stackify-stack.ll tested: llvm-lit -v `find test -name WebAssembly` unittests/MC/* Reviewers: dschuff, sunfish Subscribers: sbc100, jgravelle-google, eraman, aheejin, llvm-commits, jfb Differential Revision: https://reviews.llvm.org/D51241 llvm-svn: 340750
* Revert "[WebAssembly] Added default stack-only instruction mode for MC."Wouter van Oortmerssen2018-08-131-1/+1
| | | | | | This reverts commit 917a99b71ce21c975be7bfbf66f4040f965d9f3c. llvm-svn: 339630
* [WebAssembly] Added default stack-only instruction mode for MC.Wouter van Oortmerssen2018-08-101-1/+1
| | | | | | | | | | | | | | | | | | | | | | | Summary: Moved Explicit Locals pass to last. Made that pass obligatory. Made it convert from register to stack based instructions, and removed the registers. Fixes to related code that was expecting register based instructions. Added the correct testing flag to all tests, depending on what the format they were expecting so far. Translated one test to stack format as example: reg-stackify-stack.ll tested: llvm-lit -v `find test -name WebAssembly` unittests/MC/* Reviewers: dschuff, sunfish Subscribers: jfb, llvm-commits, aheejin, eraman, jgravelle-google, sbc100 Differential Revision: https://reviews.llvm.org/D50568 llvm-svn: 339474
* Revert "[WebAssembly] Added default stack-only instruction mode for MC."Wouter van Oortmerssen2018-07-271-1/+1
| | | | | | | This reverts commit d3c9af4179eae7793d1487d652e2d4e23844555f. (SVN revision 338164) llvm-svn: 338176
* [WebAssembly] Added default stack-only instruction mode for MC.Wouter van Oortmerssen2018-07-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | Summary: Moved Explicit Locals pass to last. Made that pass obligatory. Made it convert from register to stack based instructions, and removed the registers. Fixes to related code that was expecting register based instructions. Added the correct testing flag to all tests, depending on what the format they were expecting so far. Translated one test to stack format as example: reg-stackify-stack.ll tested: llvm-lit -v `find test -name WebAssembly` unittests/MC/* Reviewers: dschuff, sunfish Subscribers: sbc100, jgravelle-google, eraman, aheejin, llvm-commits Differential Revision: https://reviews.llvm.org/D49160 llvm-svn: 338164
* [WebAsembly] Update default triple in test files to wasm32-unknown-unkown.Sam Clegg2018-05-101-1/+1
| | | | | | | | | | 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
* [WebAssembly] Strip threadlocal attribute from globals in single thread modeDerek Schuff2018-03-201-0/+17
The default thread model for wasm is single, and in this mode thread-local global variables can be lowered identically to non-thread-local variables. Differential Revision: https://reviews.llvm.org/D44703 llvm-svn: 328049
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