[WebAssembly] Make rethrow take an except_ref type argument

Summary:
In the new wasm EH proposal, `rethrow` takes an `except_ref` argument.
This change was missing in r352598.

This patch adds `llvm.wasm.rethrow.in.catch` intrinsic. This is an
intrinsic that's gonna eventually be lowered to wasm `rethrow`
instruction, but this intrinsic can appear only within a catchpad or a
cleanuppad scope. Also this intrinsic needs to be invokable - otherwise
EH pad successor for it will not be correctly generated in clang.

This also adds lowering logic for this intrinsic in
`SelectionDAGBuilder::visitInvoke`. This routine is basically a
specialized and simplified version of
`SelectionDAGBuilder::visitTargetIntrinsic`, but we can't use it
because if is only for `CallInst`s.

This deletes the previous `llvm.wasm.rethrow` intrinsic and related
tests, which was meant to be used within a `__cxa_rethrow` library
function. Turned out this needs some more logic, so the intrinsic for
this purpose will be added later.

LateEHPrepare takes a result value of `catch` and inserts it into
matching `rethrow` as an argument.

`RETHROW_IN_CATCH` is a pseudo instruction that serves as a link between
`llvm.wasm.rethrow.in.catch` and the real wasm `rethrow` instruction. To
generate a `rethrow` instruction, we need an `except_ref` argument,
which is generated from `catch` instruction. But `catch` instrutions are
added in LateEHPrepare pass, so we use `RETHROW_IN_CATCH`, which takes
no argument, until we are able to correctly lower it to `rethrow` in
LateEHPrepare.

Reviewers: dschuff

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59352

llvm-svn: 356316

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 31768b2f9b2..6a88948ac6b 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2697,6 +2697,20 @@ void SelectionDAGBuilder::visitInvoke(const InvokeInst &I) {
     case Intrinsic::experimental_gc_statepoint:
       LowerStatepoint(ImmutableStatepoint(&I), EHPadBB);
       break;
+    case Intrinsic::wasm_rethrow_in_catch: {
+      // This is usually done in visitTargetIntrinsic, but this intrinsic is
+      // special because it can be invoked, so we manually lower it to a DAG
+      // node here.
+      SmallVector<SDValue, 8> Ops;
+      Ops.push_back(getRoot()); // inchain
+      const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+      Ops.push_back(
+          DAG.getTargetConstant(Intrinsic::wasm_rethrow_in_catch, getCurSDLoc(),
+                                TLI.getPointerTy(DAG.getDataLayout())));
+      SDVTList VTs = DAG.getVTList(ArrayRef<EVT>({MVT::Other})); // outchain
+      DAG.setRoot(DAG.getNode(ISD::INTRINSIC_VOID, getCurSDLoc(), VTs, Ops));
+      break;
+    }
     }
   } else if (I.countOperandBundlesOfType(LLVMContext::OB_deopt)) {
     // Currently we do not lower any intrinsic calls with deopt operand bundles.