[WebAssembly] Use Windows EH instructions for Wasm EH
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
diff --git a/clang/lib/CodeGen/CGCleanup.h b/clang/lib/CodeGen/CGCleanup.h
index 105c562..5530350 100644
--- a/clang/lib/CodeGen/CGCleanup.h
+++ b/clang/lib/CodeGen/CGCleanup.h
@@ -627,16 +627,21 @@
static const EHPersonality MSVC_except_handler;
static const EHPersonality MSVC_C_specific_handler;
static const EHPersonality MSVC_CxxFrameHandler3;
+ static const EHPersonality GNU_Wasm_CPlusPlus;
/// Does this personality use landingpads or the family of pad instructions
/// designed to form funclets?
- bool usesFuncletPads() const { return isMSVCPersonality(); }
+ bool usesFuncletPads() const {
+ return isMSVCPersonality() || isWasmPersonality();
+ }
bool isMSVCPersonality() const {
return this == &MSVC_except_handler || this == &MSVC_C_specific_handler ||
this == &MSVC_CxxFrameHandler3;
}
+ bool isWasmPersonality() const { return this == &GNU_Wasm_CPlusPlus; }
+
bool isMSVCXXPersonality() const { return this == &MSVC_CxxFrameHandler3; }
};
}