[WebAssembly] Split BBs after throw instructions

Summary:
`throw` instruction is a terminator in wasm, but BBs were not splitted
after `throw` instructions, causing machine instruction verifier to
fail.

This patch
- Splits BBs after `throw` instructions in WasmEHPrepare and adding an
  unreachable instruction after `throw`, which will be deleted in
  LateEHPrepare pass
- Refactors WasmEHPrepare into two member functions
- Changes the semantics of `eraseBBsAndChildren` in LateEHPrepare pass
  to match that of WasmEHPrepare pass, which is newly added. Now
  `eraseBBsAndChildren` does not delete BBs with remaining predecessors.
- Fixes style nits, making static function names conform to clang-tidy
- Re-enables the test temporarily disabled by rL346840 && rL346845

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D54571

llvm-svn: 347003

1 files changed, 5 insertions, 4 deletions

diff --git a/llvm/test/CodeGen/WebAssembly/exception.ll b/llvm/test/CodeGen/WebAssembly/exception.ll
index 0577cd43b97..b53cd0cb544 100644
--- a/llvm/test/CodeGen/WebAssembly/exception.ll
+++ b/llvm/test/CodeGen/WebAssembly/exception.ll
@@ -1,5 +1,5 @@
 ; RUN: not llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-keep-registers -exception-model=wasm
-; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-keep-registers -exception-model=wasm -mattr=+exception-handling | FileCheck -allow-deprecated-dag-overlap %s
+; RUN: llc < %s -asm-verbose=false -disable-wasm-fallthrough-return-opt -wasm-keep-registers -exception-model=wasm -mattr=+exception-handling -verify-machineinstrs | FileCheck -allow-deprecated-dag-overlap %s
 ; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-keep-registers -exception-model=wasm -mattr=+exception-handling
 
 target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
@@ -12,10 +12,11 @@ target triple = "wasm32-unknown-unknown"
 declare void @llvm.wasm.throw(i32, i8*)
 
 ; CHECK-LABEL: test_throw:
-; CHECK-NEXT: i32.const $push0=, 0
+; CHECK:      get_local $push0=, 0
 ; CHECK-NEXT: throw __cpp_exception@EVENT, $pop0
-define void @test_throw() {
-  call void @llvm.wasm.throw(i32 0, i8* null)
+; CHECK-NOT:  unreachable
+define void @test_throw(i8* %p) {
+  call void @llvm.wasm.throw(i32 0, i8* %p)
   ret void
 }