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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
62 lines
2.0 KiB
C++
62 lines
2.0 KiB
C++
//===-- WebAssemblyUtilities - WebAssembly Utility Functions ---*- C++ -*-====//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// This file contains the declaration of the WebAssembly-specific
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/// utility functions.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYUTILITIES_H
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#define LLVM_LIB_TARGET_WEBASSEMBLY_WEBASSEMBLYUTILITIES_H
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#include "llvm/CodeGen/MachineBasicBlock.h"
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namespace llvm {
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class WebAssemblyFunctionInfo;
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namespace WebAssembly {
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bool isArgument(const MachineInstr &MI);
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bool isCopy(const MachineInstr &MI);
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bool isTee(const MachineInstr &MI);
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bool isChild(const MachineInstr &MI, const WebAssemblyFunctionInfo &MFI);
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bool isCallDirect(const MachineInstr &MI);
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bool isCallIndirect(const MachineInstr &MI);
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bool isMarker(const MachineInstr &MI);
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bool mayThrow(const MachineInstr &MI);
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/// Returns the operand number of a callee, assuming the argument is a call
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/// instruction.
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unsigned getCalleeOpNo(const MachineInstr &MI);
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// Exception-related function names
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extern const char *const ClangCallTerminateFn;
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extern const char *const CxaBeginCatchFn;
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extern const char *const CxaRethrowFn;
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extern const char *const StdTerminateFn;
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extern const char *const PersonalityWrapperFn;
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/// Return the "bottom" block of an entity, which can be either a MachineLoop or
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/// WebAssemblyException. This differs from MachineLoop::getBottomBlock in that
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/// it works even if the entity is discontiguous.
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template <typename T> MachineBasicBlock *getBottom(const T *Unit) {
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MachineBasicBlock *Bottom = Unit->getHeader();
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for (MachineBasicBlock *MBB : Unit->blocks())
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if (MBB->getNumber() > Bottom->getNumber())
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Bottom = MBB;
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return Bottom;
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}
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} // end namespace WebAssembly
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} // end namespace llvm
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#endif
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