[PATCH] D81909: [WebAssembly] Fix bug in FixBrTables and use branch analysis utils

[Heejin Ahn via Phabricator via llvm-commits]

aheejin added inline comments.


================
Comment at: llvm/lib/Target/WebAssembly/WebAssemblyFixBrTableDefaults.cpp:63
+           "Expected jump or fallthrough to br_table block");
+    MI.addOperand(MF, MachineOperand::CreateMBB(TBB));
   } else {
----------------
tlively wrote:
> aheejin wrote:
> > Is it possible that both `TBB` and `FBB` are true and `FBB == MBB`?
> Yes, here's what's possible.
> 
> '_' is nullptr, 'J' is the jump table block (aka MBB), 'D' is the default block
> 
> TBB | FBB | meaning
> _ | _ | No default block, header falls through to jump table
> J | _ | No default block, header jumps to jump table
> D | _ | There is a default block, header falls through to jump table
> D | J | There is a default block, header jumps to either default or jump table
> 
Yeah, I'm talking about the last case:
D | J | There is a default block, header jumps to either default or jump table

In this case, not `TBB`, but `FBB` should be the default target. I don't think this code does it.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81909/new/

https://reviews.llvm.org/D81909