c3dfd34e54
When `try_table`'s catch clause's destination has a return type, as in
the case of catch with a concrete tag, catch_ref, and catch_all_ref. For
example:
```wasm
block exnref
try_table (catch_all_ref 0)
...
end_try_table
end_block
... use exnref ...
```
This code is not valid because the block's body type is not exnref. So
we add an unreachable after the 'end_try_table' to make the code valid
here:
```wasm
block exnref
try_table (catch_all_ref 0)
...
end_try_table
unreachable ;; Newly added
end_block
```
Because 'unreachable' is a terminator we also need to split the BB.
---
We need to handle the same thing for unwind mismatch handling. In the
code below, we create a "trampoline BB" that will be the destination for
the nested `try_table`~`end_try_table` added to fix a unwind mismatch:
```wasm
try_table (catch ... )
block exnref
...
try_table (catch_all_ref N)
some code
end_try_table
...
end_block ;; Trampoline BB
throw_ref
end_try_table
```
While the `block` added for the trampoline BB has the return type
`exnref`, its body, which contains the nested `try_table` and other
code, wouldn't have the `exnref` return type. Most times it didn't
become a problem because the block's body ended with something like `br`
or `return`, but that may not always be the case, especially when there
is a loop. So we add an `unreachable` to make the code valid here too:
```wasm
try_table (catch ... )
block exnref
...
try_table (catch_all_ref N)
some code
end_try_table
...
unreachable ;; Newly added
end_block ;; Trampoline BB
throw_ref
end_try_table
```
In this case we just append the `unreachable` at the end of the layout
predecessor BB. (This was tricky to do in the first (non-mismatch) case
because there `end_try_table` and `end_block` were added in the
beginning of an EH pad in `placeTryTableMarker` and moving
`end_try_table` and the new `unreachable` to the previous BB caused
other problems.)
---
This adds many `unreaachable`s to the output, but this adds
`unreachable` to only a few places to see if this is working. The
FileCheck lines in `exception.ll` and `cfg-stackify-eh.ll` are already
heavily redacted to only leave important control-flow instructions, so I
don't think it's worth adding `unreachable`s everywhere.
208 lines
8.9 KiB
TableGen
208 lines
8.9 KiB
TableGen
//===- WebAssemblyInstrControl.td-WebAssembly control-flow ------*- tablegen -*-
|
|
//
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
///
|
|
/// \file
|
|
/// WebAssembly control-flow code-gen constructs.
|
|
///
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
let isBranch = 1, isTerminator = 1, hasCtrlDep = 1 in {
|
|
// The condition operand is a boolean value which WebAssembly represents as i32.
|
|
defm BR_IF : I<(outs), (ins bb_op:$dst, I32:$cond),
|
|
(outs), (ins bb_op:$dst),
|
|
[(brcond I32:$cond, bb:$dst)],
|
|
"br_if \t$dst, $cond", "br_if \t$dst", 0x0d>;
|
|
let isCodeGenOnly = 1 in
|
|
defm BR_UNLESS : I<(outs), (ins bb_op:$dst, I32:$cond),
|
|
(outs), (ins bb_op:$dst), []>;
|
|
let isBarrier = 1 in
|
|
defm BR : NRI<(outs), (ins bb_op:$dst),
|
|
[(br bb:$dst)],
|
|
"br \t$dst", 0x0c>;
|
|
} // isBranch = 1, isTerminator = 1, hasCtrlDep = 1
|
|
|
|
def : Pat<(brcond (i32 (setne I32:$cond, 0)), bb:$dst),
|
|
(BR_IF bb_op:$dst, I32:$cond)>;
|
|
def : Pat<(brcond (i32 (seteq I32:$cond, 0)), bb:$dst),
|
|
(BR_UNLESS bb_op:$dst, I32:$cond)>;
|
|
def : Pat<(brcond (i32 (xor bool_node:$cond, (i32 1))), bb:$dst),
|
|
(BR_UNLESS bb_op:$dst, I32:$cond)>;
|
|
|
|
// A list of branch targets enclosed in {} and separated by comma.
|
|
// Used by br_table only.
|
|
def BrListAsmOperand : AsmOperandClass { let Name = "BrList"; }
|
|
let OperandNamespace = "WebAssembly", OperandType = "OPERAND_BRLIST" in
|
|
def brlist : Operand<i32> {
|
|
let ParserMatchClass = BrListAsmOperand;
|
|
let PrintMethod = "printBrList";
|
|
}
|
|
|
|
// Duplicating a BR_TABLE is almost never a good idea. In particular, it can
|
|
// lead to some nasty irreducibility due to tail merging when the br_table is in
|
|
// a loop.
|
|
let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1, isNotDuplicable = 1 in {
|
|
|
|
defm BR_TABLE_I32 : I<(outs), (ins I32:$index, variable_ops),
|
|
(outs), (ins brlist:$brl),
|
|
[(WebAssemblybr_table I32:$index)],
|
|
"br_table \t$index", "br_table \t$brl",
|
|
0x0e>;
|
|
// TODO: SelectionDAG's lowering insists on using a pointer as the index for
|
|
// jump tables, so in practice we don't ever use BR_TABLE_I64 in wasm32 mode
|
|
// currently.
|
|
defm BR_TABLE_I64 : I<(outs), (ins I64:$index, variable_ops),
|
|
(outs), (ins brlist:$brl),
|
|
[(WebAssemblybr_table I64:$index)],
|
|
"br_table \t$index", "br_table \t$brl",
|
|
0x0e>;
|
|
} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1, isNotDuplicable = 1
|
|
|
|
// This is technically a control-flow instruction, since all it affects is the
|
|
// IP.
|
|
defm NOP : NRI<(outs), (ins), [], "nop", 0x01>;
|
|
|
|
// Placemarkers to indicate the start or end of a block or loop scope.
|
|
// These use/clobber VALUE_STACK to prevent them from being moved into the
|
|
// middle of an expression tree.
|
|
let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in {
|
|
defm BLOCK : NRI<(outs), (ins Signature:$sig), [], "block \t$sig", 0x02>;
|
|
defm LOOP : NRI<(outs), (ins Signature:$sig), [], "loop \t$sig", 0x03>;
|
|
|
|
defm IF : I<(outs), (ins Signature:$sig, I32:$cond),
|
|
(outs), (ins Signature:$sig),
|
|
[], "if \t$sig, $cond", "if \t$sig", 0x04>;
|
|
defm ELSE : NRI<(outs), (ins), [], "else", 0x05>;
|
|
|
|
// END_BLOCK, END_LOOP, END_IF and END_FUNCTION are represented with the same
|
|
// opcode in wasm.
|
|
defm END_BLOCK : NRI<(outs), (ins), [], "end_block", 0x0b>;
|
|
defm END_LOOP : NRI<(outs), (ins), [], "end_loop", 0x0b>;
|
|
defm END_IF : NRI<(outs), (ins), [], "end_if", 0x0b>;
|
|
// Generic instruction, for disassembler.
|
|
let IsCanonical = 1 in
|
|
defm END : NRI<(outs), (ins), [], "end", 0x0b>;
|
|
let isTerminator = 1, isBarrier = 1 in
|
|
defm END_FUNCTION : NRI<(outs), (ins), [], "end_function", 0x0b>;
|
|
} // Uses = [VALUE_STACK], Defs = [VALUE_STACK]
|
|
|
|
|
|
let hasCtrlDep = 1, isBarrier = 1 in {
|
|
let isTerminator = 1 in {
|
|
let isReturn = 1 in {
|
|
|
|
defm RETURN : I<(outs), (ins variable_ops), (outs), (ins),
|
|
[(WebAssemblyreturn)],
|
|
"return", "return", 0x0f>;
|
|
// Equivalent to RETURN, for use at the end of a function when wasm
|
|
// semantics return by falling off the end of the block.
|
|
let isCodeGenOnly = 1 in
|
|
defm FALLTHROUGH_RETURN : I<(outs), (ins variable_ops), (outs), (ins), []>;
|
|
|
|
} // isReturn = 1
|
|
|
|
let IsCanonical = 1, isTrap = 1 in
|
|
defm UNREACHABLE : NRI<(outs), (ins), [(trap)], "unreachable", 0x00>;
|
|
|
|
} // isTerminator = 1
|
|
|
|
// debugtrap explicitly returns despite trapping because it is supposed to just
|
|
// get the attention of the debugger. Unfortunately, because UNREACHABLE is a
|
|
// terminator, lowering debugtrap to UNREACHABLE can create an invalid
|
|
// MachineBasicBlock when there is additional code after it. Lower it to this
|
|
// non-terminator version instead.
|
|
// TODO: Actually execute the debugger statement when running on the Web
|
|
let isTrap = 1 in
|
|
defm DEBUG_UNREACHABLE : NRI<(outs), (ins), [(debugtrap)], "unreachable", 0x00>;
|
|
|
|
} // hasCtrlDep = 1, isBarrier = 1
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Exception handling instructions
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
// A list of catch clauses attached to try_table.
|
|
def CatchListAsmOperand : AsmOperandClass { let Name = "CatchList"; }
|
|
let OperandNamespace = "WebAssembly", OperandType = "OPERAND_CATCH_LIST" in
|
|
def catch_list : Operand<i32> {
|
|
let ParserMatchClass = CatchListAsmOperand;
|
|
let PrintMethod = "printCatchList";
|
|
}
|
|
|
|
let Predicates = [HasExceptionHandling] in {
|
|
|
|
// Throwing an exception: throw / throw_ref
|
|
let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 in {
|
|
defm THROW : I<(outs), (ins tag_op:$tag, variable_ops),
|
|
(outs), (ins tag_op:$tag), [],
|
|
"throw \t$tag", "throw \t$tag", 0x08>;
|
|
defm THROW_REF : I<(outs), (ins EXNREF:$exn), (outs), (ins), [],
|
|
"throw_ref \t$exn", "throw_ref", 0x0a>;
|
|
} // isTerminator = 1, hasCtrlDep = 1, isBarrier = 1
|
|
|
|
// Region within which an exception is caught: try_table / end_try_table
|
|
let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in {
|
|
defm TRY_TABLE : I<(outs), (ins Signature:$sig, variable_ops),
|
|
(outs), (ins Signature:$sig, catch_list:$cal), [],
|
|
"try_table \t$sig", "try_table \t$sig $cal", 0x1f>;
|
|
defm END_TRY_TABLE : NRI<(outs), (ins), [], "end_try_table", 0x0b>;
|
|
} // Uses = [VALUE_STACK], Defs = [VALUE_STACK]
|
|
|
|
// Pseudo instructions that represent catch / catch_ref / catch_all /
|
|
// catch_all_ref clauses in a try_table instruction.
|
|
let hasCtrlDep = 1, hasSideEffects = 1, isCodeGenOnly = 1 in {
|
|
let variadicOpsAreDefs = 1 in {
|
|
defm CATCH : I<(outs), (ins tag_op:$tag, variable_ops),
|
|
(outs), (ins tag_op:$tag), []>;
|
|
defm CATCH_REF : I<(outs), (ins tag_op:$tag, variable_ops),
|
|
(outs), (ins tag_op:$tag), []>;
|
|
}
|
|
defm CATCH_ALL : NRI<(outs), (ins), []>;
|
|
defm CATCH_ALL_REF : I<(outs EXNREF:$dst), (ins), (outs), (ins), []>;
|
|
}
|
|
|
|
// Pseudo instructions: cleanupret / catchret
|
|
let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
|
|
isPseudo = 1, isEHScopeReturn = 1 in {
|
|
defm CLEANUPRET : NRI<(outs), (ins bb_op:$ehpad), [(cleanupret bb:$ehpad)],
|
|
"cleanupret", 0>;
|
|
defm CATCHRET : NRI<(outs), (ins bb_op:$dst, bb_op:$from),
|
|
[(catchret bb:$dst, bb:$from)], "catchret", 0>;
|
|
} // isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
|
|
// isPseudo = 1, isEHScopeReturn = 1
|
|
|
|
// Below are instructions from the legacy EH proposal. Could be deprecated if
|
|
// usage gets low enough.
|
|
|
|
// Rethrowing an exception: rethrow
|
|
// The new exnref proposal also uses this instruction as an interim pseudo
|
|
// instruction before we convert it to a THROW_REF.
|
|
// $ehpad is the EH pad where the exception to rethrow has been caught.
|
|
let isTerminator = 1, hasCtrlDep = 1, isBarrier = 1 in
|
|
defm RETHROW : NRI<(outs), (ins bb_op:$ehpad), [], "rethrow \t$ehpad", 0x09>;
|
|
|
|
// Region within which an exception is caught: try / end_try
|
|
let Uses = [VALUE_STACK], Defs = [VALUE_STACK] in {
|
|
defm TRY : NRI<(outs), (ins Signature:$sig), [], "try \t$sig", 0x06>;
|
|
defm END_TRY : NRI<(outs), (ins), [], "end_try", 0x0b>;
|
|
} // Uses = [VALUE_STACK], Defs = [VALUE_STACK]
|
|
|
|
// Catching an exception: catch / catch_all
|
|
let hasCtrlDep = 1, hasSideEffects = 1 in {
|
|
let variadicOpsAreDefs = 1 in
|
|
defm CATCH_LEGACY : I<(outs), (ins tag_op:$tag, variable_ops),
|
|
(outs), (ins tag_op:$tag), [],
|
|
"catch", "catch \t$tag", 0x07>;
|
|
defm CATCH_ALL_LEGACY : NRI<(outs), (ins), [], "catch_all", 0x19>;
|
|
}
|
|
|
|
// Delegating an exception: delegate
|
|
let isTerminator = 1, hasCtrlDep = 1, hasSideEffects = 1 in
|
|
defm DELEGATE : NRI<(outs), (ins bb_op:$dst), [], "delegate \t $dst", 0x18>;
|
|
|
|
} // Predicates = [HasExceptionHandling]
|