[WebAssembly] Fix ScopeTops info in CFGStackify for EH pads
Summary:
When creating `ScopeTops` info for `try` ~ `catch` ~ `end_try`, we
should create not only `end_try` -> `try` mapping but also `catch` ->
`try` mapping as well. If this is not created, `block` and `end_block`
markers later added may span across an existing `catch`, resulting in
the incorrect code like:
```
try
block --| (X)
catch |
end_block --|
end_try
```
Reviewers: dschuff
Subscribers: sunfish, sbc100, jgravelle-google, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58605
llvm-svn: 354945
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
index 9001787..35ca7b9 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -594,11 +594,22 @@
TII.get(WebAssembly::END_TRY));
registerTryScope(Begin, End, &MBB);
- // Track the farthest-spanning scope that ends at this point.
- int Number = Cont->getNumber();
- if (!ScopeTops[Number] ||
- ScopeTops[Number]->getNumber() > Header->getNumber())
- ScopeTops[Number] = Header;
+ // Track the farthest-spanning scope that ends at this point. We create two
+ // mappings: (BB with 'end_try' -> BB with 'try') and (BB with 'catch' -> BB
+ // with 'try'). We need to create 'catch' -> 'try' mapping here too because
+ // markers should not span across 'catch'. For example, this should not
+ // happen:
+ //
+ // try
+ // block --| (X)
+ // catch |
+ // end_block --|
+ // end_try
+ for (int Number : {Cont->getNumber(), MBB.getNumber()}) {
+ if (!ScopeTops[Number] ||
+ ScopeTops[Number]->getNumber() > Header->getNumber())
+ ScopeTops[Number] = Header;
+ }
}
void WebAssemblyCFGStackify::removeUnnecessaryInstrs(MachineFunction &MF) {