[sil-opaque-values] Fix UpdateSSA to handle checked_cast_value_br.

Author: atrick

lib/SILOptimizer/Utils/CFG.cpp

@@ -550,6 +550,14 @@ static void getEdgeArgs(TermInst *T, unsigned EdgeIdx, SILBasicBlock *NewEdgeBB,
         SuccBB->getArgument(0)->getType(), ValueOwnershipKind::Owned));
     return;
   }
+  if (auto CBI = dyn_cast<CheckedCastValueBranchInst>(T)) {
+    auto SuccBB = EdgeIdx == 0 ? CBI->getSuccessBB() : CBI->getFailureBB();
+    if (!SuccBB->getNumArguments())
+      return;
+    Args.push_back(NewEdgeBB->createPHIArgument(
+        SuccBB->getArgument(0)->getType(), ValueOwnershipKind::Owned));
+    return;
+  }
 
   if (auto *TAI = dyn_cast<TryApplyInst>(T)) {
     auto *SuccBB = EdgeIdx == 0 ? TAI->getNormalBB() : TAI->getErrorBB();

test/SILOptimizer/simplify_cfg_opaque.sil

@@ -0,0 +1,35 @@
+// RUN: %target-sil-opt -enable-sil-opaque-values -assume-parsing-unqualified-ownership-sil -enable-sil-verify-all %s -simplify-cfg | %FileCheck %s
+
+sil_stage canonical
+
+protocol P {}
+
+// Test jump threading into a destination block terminated by checked_cast_value_br.
+//
+// CHECK-LABEL: sil @testJumpThread : $@convention(thin) (Any, Any) -> () {
+// CHECK: bb0(%0 : $Any, %1 : $Any):
+// CHECK:   cond_br undef, bb1, bb4
+// CHECK: bb1:
+// CHECK:   retain_value %0 : $Any
+// CHECK:   release_value %0 : $Any
+// CHECK:   checked_cast_value_br %0 : $Any to $P, bb3, bb2
+// CHECK-LABEL: } // end sil function 'testJumpThread'
+sil @testJumpThread : $@convention(thin) (Any, Any) -> () {
+bb0(%0 : $Any, %1 : $Any):
+  cond_br undef, bb1, bb2
+bb1:
+  retain_value %0 : $Any // force jump-threading
+  br bb6(%0 : $Any)
+bb2:
+  br bb6(%1 : $Any)
+bb6(%any : $Any):
+  release_value %any : $Any // force jump-threading
+  checked_cast_value_br %any : $Any to $P, bb7, bb8
+bb7(%p : $P):
+  br bb9
+bb8:
+  br bb9
+bb9:
+  %999 = tuple ()
+  return %999 : $()
+}