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               [(WebAssemblythrow (WebAssemblywrapper texternalsym:$tag))],
135               "throw   \t$tag", "throw   \t$tag", 0x08>;
136defm RETHROW : NRI<(outs), (ins i32imm:$depth), [], "rethrow \t$depth", 0x09>;
137} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1
138// The depth argument will be computed in CFGStackify. We set it to 0 here for
139// now.
140def : Pat<(int_wasm_rethrow), (RETHROW 0)>;
141
142// Region within which an exception is caught: try / end_try
143let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in {
144defm TRY     : NRI<(outs), (ins Signature:$sig), [], "try     \t$sig", 0x06>;
145defm END_TRY : NRI<(outs), (ins), [], "end_try", 0x0b>;
146} // Uses = [VALUE_STACK], Defs = [VALUE_STACK]
147
148// Catching an exception: catch / catch_all
149let hasCtrlDep = 1, hasSideEffects = 1 in {
150// Currently 'catch' can only extract an i32, which is sufficient for C++
151// support, but according to the spec 'catch' can extract any number of values
152// based on the tag type.
153defm CATCH : I<(outs I32:$dst), (ins tag_op:$tag),
154               (outs), (ins tag_op:$tag),
155               [(set I32:$dst,
156                 (WebAssemblycatch (WebAssemblywrapper texternalsym:$tag)))],
157               "catch   \t$dst, $tag", "catch   \t$tag", 0x07>;
158defm CATCH_ALL : NRI<(outs), (ins), [], "catch_all", 0x19>;
159}
160
161// Delegating an exception: delegate
162let isTerminator = 1, hasCtrlDep = 1, hasSideEffects = 1 in
163defm DELEGATE : NRI<(outs), (ins bb_op:$dst), [], "delegate \t $dst", 0x18>;
164
165// Pseudo instructions: cleanupret / catchret
166let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
167    isPseudo = 1, isEHScopeReturn = 1 in {
168  defm CLEANUPRET : NRI<(outs), (ins), [(cleanupret)], "cleanupret", 0>;
169  defm CATCHRET : NRI<(outs), (ins bb_op:$dst, bb_op:$from),
170                      [(catchret bb:$dst, bb:$from)], "catchret", 0>;
171} // isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
172  // isPseudo = 1, isEHScopeReturn = 1
173} // Predicates = [HasExceptionHandling]
174