Don't bail out on side-effects in assertionprop (dotnet#108418)

src/coreclr/jit/assertionprop.cpp

@@ -2657,21 +2657,18 @@ GenTree* Compiler::optVNBasedFoldExpr_Call(BasicBlock* block, GenTree* parent, G
  case CORINFO_HELP_ISINSTANCEOFANY:
  case CORINFO_HELP_ISINSTANCEOFINTERFACE:
  {
- GenTree* castClsArg = call->gtArgs.GetUserArgByIndex(0)->GetNode();
- GenTree* castObjArg = call->gtArgs.GetUserArgByIndex(1)->GetNode();
-
- if ((castObjArg->gtFlags & GTF_ALL_EFFECT) != 0)
- {
- // It won't be trivial to properly extract side-effects from the call node.
- // Ideally, we only need side effects from the castClsArg argument as the call itself
- // won't throw any exceptions. But we should not forget about the EarlyNode (setup args)
- return nullptr;
- }
+ CallArg* castClsCallArg = call->gtArgs.GetUserArgByIndex(0);
+ CallArg* castObjCallArg = call->gtArgs.GetUserArgByIndex(1);
+ GenTree* castClsArg = castClsCallArg->GetNode();
+ GenTree* castObjArg = castObjCallArg->GetNode();
 
  // If object has the same VN as the cast, then the cast is effectively a no-op.
  //
  if (castObjArg->gtVNPair == call->gtVNPair)
  {
+ // if castObjArg is not simple, we replace the arg with a temp assignment and
+ // continue using that temp - it allows us reliably extract all side effects
+ castObjArg = fgMakeMultiUse(&castObjCallArg->LateNodeRef());
  return gtWrapWithSideEffects(castObjArg, call, GTF_ALL_EFFECT, true);
  }
 
@@ -2686,6 +2683,9 @@ GenTree* Compiler::optVNBasedFoldExpr_Call(BasicBlock* block, GenTree* parent, G
  CORINFO_CLASS_HANDLE castTo = gtGetHelperArgClassHandle(castClsArg);
  if (info.compCompHnd->compareTypesForCast(castFrom, castTo) == TypeCompareState::Must)
  {
+ // if castObjArg is not simple, we replace the arg with a temp assignment and
+ // continue using that temp - it allows us reliably extract all side effects
+ castObjArg = fgMakeMultiUse(&castObjCallArg->LateNodeRef());
  return gtWrapWithSideEffects(castObjArg, call, GTF_ALL_EFFECT, true);
  }
  }
@@ -5162,21 +5162,22 @@ GenTree* Compiler::optAssertionProp_Call(ASSERT_VALARG_TP assertions, GenTreeCal
  (helper == CORINFO_HELP_CHKCASTCLASS) || (helper == CORINFO_HELP_CHKCASTANY) ||
  (helper == CORINFO_HELP_CHKCASTCLASS_SPECIAL))
  {
- GenTree* castToArg = call->gtArgs.GetArgByIndex(0)->GetNode();
- GenTree* objArg = call->gtArgs.GetArgByIndex(1)->GetNode();
+ CallArg* castToCallArg = call->gtArgs.GetArgByIndex(0);
+ CallArg* objCallArg = call->gtArgs.GetArgByIndex(1);
+ GenTree* castToArg = castToCallArg->GetNode();
+ GenTree* objArg = objCallArg->GetNode();
 
- // We require objArg to be side effect free due to limitations in gtWrapWithSideEffects
- if ((objArg->gtFlags & GTF_ALL_EFFECT) == 0)
+ const unsigned index = optAssertionIsSubtype(objArg, castToArg, assertions);
+ if (index != NO_ASSERTION_INDEX)
  {
- const unsigned index = optAssertionIsSubtype(objArg, castToArg, assertions);
- if (index != NO_ASSERTION_INDEX)
- {
- JITDUMP("\nDid VN based subtype prop for index #%02u in " FMT_BB ":\n", index, compCurBB->bbNum);
- DISPTREE(call);
-
- objArg = gtWrapWithSideEffects(objArg, call, GTF_SIDE_EFFECT, true);
- return optAssertionProp_Update(objArg, call, stmt);
- }
+ JITDUMP("\nDid VN based subtype prop for index #%02u in " FMT_BB ":\n", index, compCurBB->bbNum);
+ DISPTREE(call);
+
+ // if castObjArg is not simple, we replace the arg with a temp assignment and
+ // continue using that temp - it allows us reliably extract all side effects
+ objArg = fgMakeMultiUse(&objCallArg->LateNodeRef());
+ objArg = gtWrapWithSideEffects(objArg, call, GTF_SIDE_EFFECT, true);
+ return optAssertionProp_Update(objArg, call, stmt);
  }
 
  // Leave a hint for fgLateCastExpansion that obj is never null.