[WebAssembly] Treat __cxa_end_catch not longjmpable in Emscripten SjLj

In D117610 we treated `__cxa_end_catch` longjmpable even though it was
not to make unwind destination relationships correct. But we only need
to do this in Wasm SjLj, and doing this in Emscripten SjLj does not make
the code incorrect but add unnecessary invokes. This CL treats
`__cxa_end_catch` longjmpable only in Wasm SjLj.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D117943

llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp

@@ -630,9 +630,9 @@ static bool canLongjmp(const Value *Callee) {
 
   // Exception-catching related functions
   //
-  // We intentionally excluded __cxa_end_catch here even though it surely cannot
-  // longjmp, in order to maintain the unwind relationship from all existing
-  // catchpads (and calls within them) to catch.dispatch.longjmp.
+  // We intentionally treat __cxa_end_catch longjmpable in Wasm SjLj even though
+  // it surely cannot longjmp, in order to maintain the unwind relationship from
+  // all existing catchpads (and calls within them) to catch.dispatch.longjmp.
   //
   // In Wasm EH + Wasm SjLj, we
   // 1. Make all catchswitch and cleanuppad that unwind to caller unwind to
@@ -663,6 +663,8 @@ static bool canLongjmp(const Value *Callee) {
   //
   // The comment block in findWasmUnwindDestinations() in
   // SelectionDAGBuilder.cpp is addressing a similar problem.
+  if (CalleeName == "__cxa_end_catch")
+    return WebAssembly::WasmEnableSjLj;
   if (CalleeName == "__cxa_begin_catch" ||
       CalleeName == "__cxa_allocate_exception" || CalleeName == "__cxa_throw" ||
       CalleeName == "__clang_call_terminate")

llvm/test/CodeGen/WebAssembly/lower-em-ehsjlj.ll

@@ -33,21 +33,23 @@ entry:
 ; CHECK-NEXT: %[[CMP:.*]] = icmp eq i32 %__THREW__.val, 1
 ; CHECK-NEXT: br i1 %[[CMP]], label %lpad, label %try.cont
 
-; longjmp checking part
-; CHECK:    if.then1:
-; CHECK:      call i32 @testSetjmp
-
+; CHECK:    lpad:
 lpad:                                             ; preds = %entry
   %0 = landingpad { i8*, i32 }
           catch i8* null
   %1 = extractvalue { i8*, i32 } %0, 0
   %2 = extractvalue { i8*, i32 } %0, 1
+; CHECK-NOT:  call {{.*}} void @__invoke_void(void ()* @__cxa_end_catch)
   %3 = call i8* @__cxa_begin_catch(i8* %1) #2
   call void @__cxa_end_catch()
   br label %try.cont
 
 try.cont:                                         ; preds = %lpad, %entry
   ret void
+
+; longjmp checking part
+; CHECK:    if.then1:
+; CHECK:      call i32 @testSetjmp
 }
 
 ; @foo can either throw an exception or longjmp. Because this function doesn't