[all-commits] [llvm/llvm-project] da01a9: [WebAssemblly] Fix EHPadStack update in fixCallUnw...

[Heejin Ahn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: da01a9db8bb4d0ba362e1956ef7fa9bdd5e3b464
      https://github.com/llvm/llvm-project/commit/da01a9db8bb4d0ba362e1956ef7fa9bdd5e3b464
  Author: Heejin Ahn <aheejin at gmail.com>
  Date:   2021-02-17 (Wed, 17 Feb 2021)

  Changed paths:
    M llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
    M llvm/test/CodeGen/WebAssembly/cfg-stackify-eh.ll

  Log Message:
  -----------
  [WebAssemblly] Fix EHPadStack update in fixCallUnwindMismatches

Updating `EHPadStack` with respect to `TRY` and `CATCH` instructions
have to be done after checking all other conditions, not before. Because
we did this before checking other conditions, when we encounter `TRY`
and we want to record the current mismatching range, we already have
popped up the entry from `EHPadStack`, which we need to access to record
the range.

The `baz` call in the added test needs try-delegate because the previous
TRY marker placement for `quux` was placed before `baz`, because `baz`'s
return value was stackified in RegStackify. If this wasn't stackified
this try-delegate is not strictly necessary, but at the moment it is not
easy to identify cases like this. I plan to transfer `nounwind`
attributes from the LLVM IR to prevent cases like this. The call in the
test does not have `unwind` attribute in order to test this bug, but in
many cases of this pattern the previous call has `nounwind` attribute.

Reviewed By: tlively

Differential Revision: https://reviews.llvm.org/D96711