Summary:
Because in wasm we merge all catch clauses into one big catchpad, in
case none of the types in catch handlers matches after we test against
each of them, we should unwind to the next EH enclosing scope. For this,
we should NOT use a call to `__cxa_rethrow` but rather a call to our own
rethrow intrinsic, because what we're trying to do here is just to
transfer the control flow into the next enclosing EH pad (or the
caller). Calls to `__cxa_rethrow` should only be used after a call to
`__cxa_begin_catch`.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, sunfish, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59353
llvm-svn: 356317
Summary:
clang's current wasm EH implementation is a non-MVP feature in progress.
We had a `-mexception-handling` wasm feature but were not using it. This
patch hides the non-MVP wasm EH behind a flag, so it does not affect
other code for now.
Reviewers: dschuff
Subscribers: sbc100, jgravelle-google, sunfish, cfe-commits
Differential Revision: https://reviews.llvm.org/D47614
llvm-svn: 333716
Summary:
Because wasm control flow needs to be structured, using WinEH
instructions to support wasm EH brings several benefits. This patch
makes wasm EH uses Windows EH instructions, with some changes:
1. Because wasm uses a single catch block to catch all C++ exceptions,
this merges all catch clauses into a single catchpad, within which we
test the EH selector as in Itanium EH.
2. Generates a call to `__clang_call_terminate` in case a cleanup
throws. Wasm does not have a runtime to handle this.
3. In case there is no catch-all clause, inserts a call to
`__cxa_rethrow` at the end of a catchpad in order to unwind to an
enclosing EH scope.
Reviewers: majnemer, dschuff
Subscribers: jfb, sbc100, jgravelle-google, sunfish, cfe-commits
Differential Revision: https://reviews.llvm.org/D44931
llvm-svn: 333703
Heejin Ahn