In `LateEHPrepare::addCatchAlls`, the current code tries to get the
iterator's debug info even when it is `MachineBasicBlock::end()`. This
fixes the bug by adding empty debug info instead in that case.
Reviewed By: tlively
Differential Revision: https://reviews.llvm.org/D97679
Currently exception.mir runs LateEHPrepare and CFGStackify, but some
tests I'm planning to add shouldn't be run with LateEHPrepare, because
it is convenient to only run CFGStackify when testing things like unwind
mismatches and it is easier to add tests that are in phase right before
CFGStackify. This splits existing exception.mir into two files;
cfg-stackify-eh.mir will only run CFGStackify. Note that
`eh_label_tests` tests both LateEHPrepare and CFGStackify, so it is
still in exception.mir. `rethrow_arg_tests` has been converted to the
post-LateEHPrepare form to be moved into cfg-stackify-eh.mir, like
removing `CATCHRET` and such, because it does not really test anything
in LateEHPrepare.
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D97175
Usually `EH_LABEL`s are placed in
- Before an `invoke` (which becomes calls in the backend)
- After an `invoke`
- At the start of an EH pad
I don't know exactly why, but I noticed there are cases of multiple, not
a single, `EH_LABEL` instructions in the beginning of an EH pad. In that
case `global.set` instruction placed to restore `__stack_pointer` ended
up between two `EH_LABEL` instructions before `CATCH`. It should follow
after the `EH_LABEL`s and `CATCH`. This CL fixes that case.
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D96970
Previously we assumed `rethrow`'s argument was always 0, but it turned
out `rethrow` follows the same rule with `br` or `delegate`:
https://github.com/WebAssembly/exception-handling/pull/137https://github.com/WebAssembly/exception-handling/issues/146#issuecomment-777349038
Currently `rethrow`s generated by our backend always rethrow the
exception caught by the innermost enclosing catch, so this adds a
function to compute that and replaces `rethrow`'s argument with its
computed result.
This also renames `EHPadStack` in `InstPrinter` to `TryStack`, because
in CFGStackify we use `EHPadStack` to mean the range between
`catch`~`end`, while in `InstPrinter` we used it to mean the range
between `try`~`catch`, so choosing different names would look clearer.
Doesn't contain any functional changes in `InstPrinter`.
Reviewed By: dschuff
Differential Revision: https://reviews.llvm.org/D96595
This removes unreachable EH pads in LateEHPrepare. This is not for
optimization but for preparation for CFGStackify. In CFGStackify, we
determine where to place `try` marker by computing the nearest common
dominator of all predecessors of an EH pad, but when an EH pad does not
have a predecessor, it becomes tricky. We can insert an empty dummy BB
before the EH pad and place the `try` there, but removing unreachable EH
pads is simpler.
This moves an existing exception label test from eh-label.mir to
exception.mir and adds a new test there.
This also adds some comments to existing methods.
Reviewed By: dschuff, tlively
Differential Revision: https://reviews.llvm.org/D94044
Heejin Ahn