[WebAssembly] Add isEHScopeReturn instruction property

Summary:
So far, `isReturn` property is used to mean both a return instruction
from a functon and the end of an EH scope, a scope that starts with a EH
scope entry BB and ends with a catchret or a cleanupret instruction.
Because WinEH uses funclets, all EH-scope-ending instructions are also
real return instruction from a function. But for wasm, they only serve
as the end marker of an EH scope but not a return instruction that
exits a function. This mismatch caused incorrect prolog and epilog
generation in wasm EH scopes. This patch fixes this.

This patch is in the same vein with rL333045, which splits
`MachineBasicBlock::isEHFuncletEntry` into `isEHFuncletEntry` and
`isEHScopeEntry`.

Reviewers: dschuff

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

Differential Revision: https://reviews.llvm.org/D50653

llvm-svn: 340325

1 files changed, 1 insertions, 3 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
index cd2336393cc..a987906e087 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrControl.td
@@ -185,10 +185,8 @@ defm CATCH_ALL : NRI<(outs), (ins), [], "catch_all", 0x05>;
 }
 
 // Pseudo instructions: cleanupret / catchret
-// They are not return instructions in wasm, but setting 'isReturn' to true as
-// in X86 is necessary for computing EH scope membership.
 let isTerminator = 1, hasSideEffects = 1, isBarrier = 1, hasCtrlDep = 1,
-    isCodeGenOnly = 1, isReturn = 1 in {
+    isCodeGenOnly = 1, isEHScopeReturn = 1 in {
   defm CLEANUPRET : NRI<(outs), (ins), [(cleanupret)], "", 0>;
   defm CATCHRET : NRI<(outs), (ins bb_op:$dst, bb_op:$from),
                    [(catchret bb:$dst, bb:$from)], "", 0>;