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* [WebAssembly] Exception handling: Switch to the new proposalHeejin Ahn2019-01-301-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This switches the EH implementation to the new proposal: https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md (The previous proposal was https://github.com/WebAssembly/exception-handling/blob/master/proposals/old/Exceptions.md) - Instruction changes - Now we have one single `catch` instruction that returns a except_ref value - `throw` now can take variable number of operations - `rethrow` does not have 'depth' argument anymore - `br_on_exn` queries an except_ref to see if it matches the tag and branches to the given label if true. - `extract_exception` is a pseudo instruction that simulates popping values from wasm stack. This is to make `br_on_exn`, a very special instruction, work: `br_on_exn` puts values onto the stack only if it is taken, and the # of values can vay depending on the tag. - Now there's only one `catch` per `try`, this patch removes all special handling for terminate pad with a call to `__clang_call_terminate`. Before it was the only case there are two catch clauses (a normal `catch` and `catch_all` per `try`). - Make `rethrow` act as a terminator like `throw`. This splits BB after `rethrow` in WasmEHPrepare, and deletes an unnecessary `unreachable` after `rethrow` in LateEHPrepare. - Now we stop at all catchpads (because we add wasm `catch` instruction that catches all exceptions), this creates new `findWasmUnwindDestinations` function in SelectionDAGBuilder. - Now we use `br_on_exn` instrution to figure out if an except_ref matches the current tag or not, LateEHPrepare generates this sequence for catch pads: ``` catch block i32 br_on_exn $__cpp_exception end_block extract_exception ``` - Branch analysis for `br_on_exn` in WebAssemblyInstrInfo - Other various misc. changes to switch to the new proposal. Reviewers: dschuff Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D57134 llvm-svn: 352598
* Update the file headers across all of the LLVM projects in the monorepoChandler Carruth2019-01-191-4/+3
| | | | | | | | | | | | | | | | | to reflect the new license. We understand that people may be surprised that we're moving the header entirely to discuss the new license. We checked this carefully with the Foundation's lawyer and we believe this is the correct approach. Essentially, all code in the project is now made available by the LLVM project under our new license, so you will see that the license headers include that license only. Some of our contributors have contributed code under our old license, and accordingly, we have retained a copy of our old license notice in the top-level files in each project and repository. llvm-svn: 351636
* [WebAssembly] Add support for the event sectionHeejin Ahn2018-11-141-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This adds support for the 'event section' specified in the exception handling proposal. (This was named 'exception section' first, but later renamed to 'event section' to take possibilities of other kinds of events into consideration. But currently we only store exception info in this section.) The event section is added between the global section and the export section. This is for ease of validation per request of the V8 team. This patch: - Creates the event symbol type, which is a weak symbol - Makes 'throw' instruction take the event symbol '__cpp_exception' - Adds relocation support for events - Adds WasmObjectWriter / WasmObjectFile (Reader) support - Adds obj2yaml / yaml2obj support - Adds '.eventtype' printing support Reviewers: dschuff, sbc100, aardappel Subscribers: jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D54096 llvm-svn: 346825
* Reland "[WebAssembly] LSDA info generation"Heejin Ahn2018-10-251-0/+81
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Summary: This adds support for LSDA (exception table) generation for wasm EH. Wasm EH mostly follows the structure of Itanium-style exception tables, with one exception: a call site table entry in wasm EH corresponds to not a call site but a landing pad. In wasm EH, the VM is responsible for stack unwinding. After an exception occurs and the stack is unwound, the control flow is transferred to wasm 'catch' instruction by the VM, after which the personality function is called from the compiler-generated code. (Refer to WasmEHPrepare pass for more information on this part.) This patch: - Changes wasm.landingpad.index intrinsic to take a token argument, to make this 1:1 match with a catchpad instruction - Stores landingpad index info and catch type info MachineFunction in before instruction selection - Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an exception table - Adds WasmException class with overridden methods for table generation - Adds support for LSDA section in Wasm object writer Reviewers: dschuff, sbc100, rnk Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D52748 llvm-svn: 345345
* Revert "[WebAssembly] LSDA info generation"Krasimir Georgiev2018-10-161-81/+0
| | | | | | | | This reverts commit r344575. Newly introduced test eh-lsda.ll.test fails with use-after-free under ASAN build. llvm-svn: 344639
* [WebAssembly] LSDA info generationHeejin Ahn2018-10-161-0/+81
Summary: This adds support for LSDA (exception table) generation for wasm EH. Wasm EH mostly follows the structure of Itanium-style exception tables, with one exception: a call site table entry in wasm EH corresponds to not a call site but a landing pad. In wasm EH, the VM is responsible for stack unwinding. After an exception occurs and the stack is unwound, the control flow is transferred to wasm 'catch' instruction by the VM, after which the personality function is called from the compiler-generated code. (Refer to WasmEHPrepare pass for more information on this part.) This patch: - Changes wasm.landingpad.index intrinsic to take a token argument, to make this 1:1 match with a catchpad instruction - Stores landingpad index info and catch type info MachineFunction in before instruction selection - Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an exception table - Adds WasmException class with overridden methods for table generation - Adds support for LSDA section in Wasm object writer Reviewers: dschuff, sbc100, rnk Subscribers: mgorny, jgravelle-google, sunfish, llvm-commits Differential Revision: https://reviews.llvm.org/D52748 llvm-svn: 344575
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