[WebAssembly] Fix bugs in rethrow depth counting and InstPrinter
Summary:
EH stack depth is incremented at `try` and decremented at `catch`. When
there are more than two catch instructions for a try instruction, we
shouldn't count non-first catches when calculating EH stack depths.
This patch fixes two bugs:
- CFGStackify: Exclude `catch_all` in the terminate catch pad when
calculating EH pad stack, because when we have multiple catches for a
try we should count only the first catch instruction when calculating
EH pad stack.
- InstPrinter: The initial intention was also to exclude non-first
catches, but it didn't account nested try-catches, so it failed on
this case:
```
try
try
catch
end
catch <-- (1)
end
```
In the example, when we are at the catch (1), the last seen EH
instruction is not `try` but `end_try`, violating the wrong assumption.
We don't need these after we switch to the second proposal because there
is gonna be only one `catch` instruction. But anyway before then these
bugfixes are necessary for keep trunk in working state.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits
Differential Revision: https://reviews.llvm.org/D53819
llvm-svn: 346029
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
index a3b3901..b195501 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyCFGStackify.cpp
@@ -739,7 +739,20 @@
case WebAssembly::CATCH_I32:
case WebAssembly::CATCH_I64:
case WebAssembly::CATCH_ALL:
- EHPadStack.push_back(&MBB);
+ // Currently the only case there are more than one catch for a try is
+ // for catch terminate pad, in the form of
+ // try
+ // catch
+ // call @__clang_call_terminate
+ // unreachable
+ // catch_all
+ // call @std::terminate
+ // unreachable
+ // end
+ // So we shouldn't push the current BB for the second catch_all block
+ // here.
+ if (!WebAssembly::isCatchAllTerminatePad(MBB))
+ EHPadStack.push_back(&MBB);
break;
case WebAssembly::LOOP: