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.
114 lines
3.1 KiB
YAML
114 lines
3.1 KiB
YAML
# RUN: llc -mtriple=wasm32-unknown-unknown -wasm-use-legacy-eh -exception-model=wasm -mattr=+exception-handling -run-pass wasm-late-eh-prepare -run-pass wasm-cfg-stackify %s -o - | FileCheck %s
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--- |
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target triple = "wasm32-unknown-unknown"
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declare i32 @__gxx_wasm_personality_v0(...)
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declare void @foo()
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define void @eh_label_test() personality ptr @__gxx_wasm_personality_v0 {
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ret void
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}
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define void @unreachable_ehpad_test() personality ptr @__gxx_wasm_personality_v0 {
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ret void
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}
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define void @empty_cleanuppad_test() personality ptr @__gxx_wasm_personality_v0 {
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ret void
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}
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...
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---
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# This tests 'try' and 'catch' instructions are correctly placed with respect to
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# EH_LABEL instructions.
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# CHECK-LABEL: name: eh_label_test
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name: eh_label_test
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liveins:
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- { reg: '$arguments' }
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frameInfo:
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hasCalls: true
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body: |
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bb.0:
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; TRY should be before EH_LABEL wrappers of throwing calls
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; CHECK: bb.0
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; CHECK: TRY
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; CHECK-NEXT: EH_LABEL
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; CHECK-NEXT: CALL @foo
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; CHECK-NEXT: EH_LABEL
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successors: %bb.1, %bb.2
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EH_LABEL <mcsymbol .Ltmp0>
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CALL @foo, implicit-def dead $arguments, implicit $sp32, implicit $sp64
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EH_LABEL <mcsymbol .Ltmp1>
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BR %bb.2, implicit-def dead $arguments
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bb.1 (landing-pad):
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; predecessors: %bb.0
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successors: %bb.2
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; CATCH_ALL_LEGACY should be after EH_LABELs in the beginning of an EH pad.
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; (Sometimes there are multiple EH_LABELs in an EH pad. This test tests
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; that.) GLOBAL_SET should follow right after that.
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; CHECK: bb.1
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; CHECK: EH_LABEL
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; CHECK: EH_LABEL
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; CHECK-NEXT: CATCH_ALL_LEGACY
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; CHECK-NEXT: GLOBAL_SET_I32
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EH_LABEL <mcsymbol .Ltmp2>
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EH_LABEL <mcsymbol .Ltmp2>
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CATCHRET %bb.2, %bb.1, implicit-def dead $arguments
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bb.2:
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; predecessors: %bb.0, %bb.1
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RETURN implicit-def dead $arguments
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...
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---
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# Unreachable EH pads should be removed by LateEHPrepare.
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# CHECK-LABEL: name: unreachable_ehpad_test
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name: unreachable_ehpad_test
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liveins:
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- { reg: '$arguments' }
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body: |
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; CHECK: bb.0
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bb.0:
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successors: %bb.2
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BR %bb.2, implicit-def dead $arguments
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; This EH pad is unreachable, so it should be removed by LateEHPrepare
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; CHECK-NOT: bb.1 (landing-pad)
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bb.1 (landing-pad):
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successors: %bb.2
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EH_LABEL <mcsymbol .Ltmp2>
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CATCHRET %bb.2, %bb.1, implicit-def dead $arguments
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; This BB should remain (it will be renumbered to bb.1)
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; CHECK: bb.1
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bb.2:
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; predecessors: %bb.0, %bb.1
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RETURN implicit-def dead $arguments
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...
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---
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# Regression test for a bug that LateEHPrepare::addCatchAll didn't handle empty
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# cleanup pads. (It tried to get debug info from end() iterator.)
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name: empty_cleanuppad_test
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liveins:
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- { reg: '$arguments' }
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body: |
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bb.0:
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successors: %bb.1, %bb.3
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EH_LABEL <mcsymbol .Ltmp0>
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CALL @foo, implicit-def dead $arguments, implicit $sp32, implicit $sp64
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EH_LABEL <mcsymbol .Ltmp1>
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BR %bb.3, implicit-def dead $arguments
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;; Empty cleanuppad
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bb.1 (landing-pad):
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successors: %bb.2
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EH_LABEL <mcsymbol .Ltmp2>
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bb.2:
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successors: %bb.3
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CLEANUPRET %bb.1, implicit-def dead $arguments
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bb.3:
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RETURN implicit-def dead $arguments
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...
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