[WebAssembly] Add support for exception handling instructions

Summary:
This adds backend support for throw, rethrow, try, and try_end instructions.
This needs the corresponding clang builtin support:
https://reviews.llvm.org/D34783
This follows the Wasm exception handling proposal in
https://github.com/WebAssembly/exception-handling/blob/master/proposals/Exceptions.md

Reviewers: sunfish, dschuff

Reviewed By: dschuff

Subscribers: jfb, sbc100, jgravelle-google

Differential Revision: https://reviews.llvm.org/D34826

llvm-svn: 306774

1 files changed, 22 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/WebAssembly/exception.ll b/llvm/test/CodeGen/WebAssembly/exception.ll
new file mode 100644
index 00000000000..eedb5c78b24
--- /dev/null
+++ b/llvm/test/CodeGen/WebAssembly/exception.ll
@@ -0,0 +1,22 @@
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -disable-wasm-explicit-locals | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown-wasm"
+
+declare void @llvm.wasm.throw(i32, i8*)
+declare void @llvm.wasm.rethrow()
+
+; CHECK-LABEL: throw:
+; CHECK-NEXT: i32.const $push0=, 0
+; CHECK-NEXT: throw 0, $pop0
+define void @throw() {
+  call void @llvm.wasm.throw(i32 0, i8* null)
+  ret void
+}
+
+; CHECK-LABEL: rethrow:
+; CHECK-NEXT: rethrow 0
+define void @rethrow() {
+  call void @llvm.wasm.rethrow()
+  ret void
+}