1//===- WebAssemblyInstrControl.td-WebAssembly control-flow ------*- tablegen -*- 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8/// 9/// \file 10/// WebAssembly control-flow code-gen constructs. 11/// 12//===----------------------------------------------------------------------===// 13 14let isBranch = 1, isTerminator = 1, hasCtrlDep = 1 in { 15// The condition operand is a boolean value which WebAssembly represents as i32. 16defm BR_IF : I<(outs), (ins bb_op:$dst, I32:$cond), 17 (outs), (ins bb_op:$dst), 18 [(brcond I32:$cond, bb:$dst)], 19 "br_if \t$dst, $cond", "br_if \t$dst", 0x0d>; 20let isCodeGenOnly = 1 in 21defm BR_UNLESS : I<(outs), (ins bb_op:$dst, I32:$cond), 22 (outs), (ins bb_op:$dst), []>; 23let isBarrier = 1 in 24defm BR : NRI<(outs), (ins bb_op:$dst), 25 [(br bb:$dst)], 26 "br \t$dst", 0x0c>; 27} // isBranch = 1, isTerminator = 1, hasCtrlDep = 1 28 29def : Pat<(brcond (i32 (setne I32:$cond, 0)), bb:$dst), 30 (BR_IF bb_op:$dst, I32:$cond)>; 31def : Pat<(brcond (i32 (seteq I32:$cond, 0)), bb:$dst), 32 (BR_UNLESS bb_op:$dst, I32:$cond)>; 33def : Pat<(brcond (i32 (xor bool_node:$cond, (i32 1))), bb:$dst), 34 (BR_UNLESS bb_op:$dst, I32:$cond)>; 35 36// A list of branch targets enclosed in {} and separated by comma. 37// Used by br_table only. 38def BrListAsmOperand : AsmOperandClass { let Name = "BrList"; } 39let OperandNamespace = "WebAssembly", OperandType = "OPERAND_BRLIST" in 40def brlist : Operand<i32> { 41 let ParserMatchClass = BrListAsmOperand; 42 let PrintMethod = "printBrList"; 43} 44 45// Duplicating a BR_TABLE is almost never a good idea. In particular, it can 46// lead to some nasty irreducibility due to tail merging when the br_table is in 47// a loop. 48let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1, isNotDuplicable = 1 in { 49 50defm BR_TABLE_I32 : I<(outs), (ins I32:$index, variable_ops), 51 (outs), (ins brlist:$brl), 52 [(WebAssemblybr_table I32:$index)], 53 "br_table \t$index", "br_table \t$brl", 54 0x0e>; 55// TODO: SelectionDAG's lowering insists on using a pointer as the index for 56// jump tables, so in practice we don't ever use BR_TABLE_I64 in wasm32 mode 57// currently. 58defm BR_TABLE_I64 : I<(outs), (ins I64:$index, variable_ops), 59 (outs), (ins brlist:$brl), 60 [(WebAssemblybr_table I64:$index)], 61 "br_table \t$index", "br_table \t$brl", 62 0x0e>; 63} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1, isNotDuplicable = 1 64 65// This is technically a control-flow instruction, since all it affects is the 66// IP. 67defm NOP : NRI<(outs), (ins), [], "nop", 0x01>; 68 69// Placemarkers to indicate the start or end of a block or loop scope. 70// These use/clobber VALUE_STACK to prevent them from being moved into the 71// middle of an expression tree. 72let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in { 73defm BLOCK : NRI<(outs), (ins Signature:$sig), [], "block \t$sig", 0x02>; 74defm LOOP : NRI<(outs), (ins Signature:$sig), [], "loop \t$sig", 0x03>; 75 76defm IF : I<(outs), (ins Signature:$sig, I32:$cond), 77 (outs), (ins Signature:$sig), 78 [], "if \t$sig, $cond", "if \t$sig", 0x04>; 79defm ELSE : NRI<(outs), (ins), [], "else", 0x05>; 80 81// END_BLOCK, END_LOOP, END_IF and END_FUNCTION are represented with the same 82// opcode in wasm. 83defm END_BLOCK : NRI<(outs), (ins), [], "end_block", 0x0b>; 84defm END_LOOP : NRI<(outs), (ins), [], "end_loop", 0x0b>; 85defm END_IF : NRI<(outs), (ins), [], "end_if", 0x0b>; 86// Generic instruction, for disassembler. 87let IsCanonical = 1 in 88defm END : NRI<(outs), (ins), [], "end", 0x0b>; 89let isTerminator = 1, isBarrier = 1 in 90defm END_FUNCTION : NRI<(outs), (ins), [], "end_function", 0x0b>; 91} // Uses = [VALUE_STACK], Defs = [VALUE_STACK] 92 93 94let hasCtrlDep = 1, isBarrier = 1 in { 95let isTerminator = 1 in { 96let isReturn = 1 in { 97 98defm RETURN : I<(outs), (ins variable_ops), (outs), (ins), 99 [(WebAssemblyreturn)], 100 "return", "return", 0x0f>; 101// Equivalent to RETURN, for use at the end of a function when wasm 102// semantics return by falling off the end of the block. 103let isCodeGenOnly = 1 in 104defm FALLTHROUGH_RETURN : I<(outs), (ins variable_ops), (outs), (ins), []>; 105 106} // isReturn = 1 107 108let IsCanonical = 1, isTrap = 1 in 109defm UNREACHABLE : NRI<(outs), (ins), [(trap)], "unreachable", 0x00>; 110 111} // isTerminator = 1 112 113// debugtrap explicitly returns despite trapping because it is supposed to just 114// get the attention of the debugger. Unfortunately, because UNREACHABLE is a 115// terminator, lowering debugtrap to UNREACHABLE can create an invalid 116// MachineBasicBlock when there is additional code after it. Lower it to this 117// non-terminator version instead. 118// TODO: Actually execute the debugger statement when running on the Web 119let isTrap = 1 in 120defm DEBUG_UNREACHABLE : NRI<(outs), (ins), [(debugtrap)], "unreachable", 0x00>; 121 122} // hasCtrlDep = 1, isBarrier = 1 123 124//===----------------------------------------------------------------------===// 125// Exception handling instructions 126//===----------------------------------------------------------------------===// 127 128let Predicates = [HasExceptionHandling] in { 129 130// Throwing an exception: throw / rethrow 131let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 in { 132defm THROW : I<(outs), (ins tag_op:$tag, variable_ops), 133 (outs), (ins tag_op:$tag), [], 134 "throw \t$tag", "throw \t$tag", 0x08>; 135defm RETHROW : NRI<(outs), (ins i32imm:$depth), [], "rethrow \t$depth", 0x09>; 136} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 137// The depth argument will be computed in CFGStackify. We set it to 0 here for 138// now. 139def : Pat<(int_wasm_rethrow), (RETHROW 0)>; 140 141// Region within which an exception is caught: try / end_try 142let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in { 143defm TRY : NRI<(outs), (ins Signature:$sig), [], "try \t$sig", 0x06>; 144defm END_TRY : NRI<(outs), (ins), [], "end_try", 0x0b>; 145} // Uses = [VALUE_STACK], Defs = [VALUE_STACK] 146 147// Catching an exception: catch / catch_all 148let hasCtrlDep = 1, hasSideEffects = 1 in { 149let variadicOpsAreDefs = 1 in 150defm CATCH : I<(outs), (ins tag_op:$tag, variable_ops), 151 (outs), (ins tag_op:$tag), [], 152 "catch", "catch \t$tag", 0x07>; 153defm CATCH_ALL : NRI<(outs), (ins), [], "catch_all", 0x19>; 154} 155 156// Delegating an exception: delegate 157let isTerminator = 1, hasCtrlDep = 1, hasSideEffects = 1 in 158defm DELEGATE : NRI<(outs), (ins bb_op:$dst), [], "delegate \t $dst", 0x18>; 159 160// Pseudo instructions: cleanupret / catchret 161let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1, 162 isPseudo = 1, isEHScopeReturn = 1 in { 163 defm CLEANUPRET : NRI<(outs), (ins), [(cleanupret)], "cleanupret", 0>; 164 defm CATCHRET : NRI<(outs), (ins bb_op:$dst, bb_op:$from), 165 [(catchret bb:$dst, bb:$from)], "catchret", 0>; 166} // isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1, 167 // isPseudo = 1, isEHScopeReturn = 1 168} // Predicates = [HasExceptionHandling] 169