Merge pull request #12085 from swiftix/open-archtypes-tracker-fixes

Fix the hang in the SILBuilder::addOpenedArchetypeOperands

Author: swiftix

lib/SIL/SILBuilder.cpp

@@ -410,10 +410,13 @@ void SILBuilder::addOpenedArchetypeOperands(SILInstruction *I) {
   if (I && I->getNumTypeDependentOperands() > 0)
     return;
 
+  // Keep track of already visited instructions to avoid infinite loops.
+  SmallPtrSet<SILInstruction *, 8> Visited;
+
   while (I && I->getNumOperands() == 1 &&
          I->getNumTypeDependentOperands() == 0) {
     I = dyn_cast<SILInstruction>(I->getOperand(0));
-    if (!I)
+    if (!I || !Visited.insert(I).second)
       return;
     // If it is a definition of an opened archetype,
     // register it and exit.

test/SILOptimizer/opened_archetype_operands_tracking.sil

@@ -1,4 +1,5 @@
 // RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -sil-inline-generics -enable-sil-verify-all %s -O | %FileCheck %s
+// RUN: %target-sil-opt -assume-parsing-unqualified-ownership-sil -simplify-cfg -enable-sil-verify-all %s -O | %FileCheck --check-prefix=CHECK-SIMPLIFY-CFG %s
 
 // Check some corner cases related to tracking of opened archetypes.
 // For example, the compiler used to crash compiling the "process" function (rdar://28024272)
@@ -262,3 +263,53 @@ bb0(%0 : $AnyObject):
   return %8 : $()
 } // end sil function 'check_removal_of_unregistered_archetype_def'
 
+// Check that even in case of unreacheable blocks the compiler does not hang
+// in SILBuilder::addOpenedArchetypeOperands. rdar://problem/34602036
+
+enum MyOptional<T> {
+  case none
+  case some(T)
+}
+
+class C {
+  var this : MyOptional<C>
+  init()
+}
+
+// CHECK-SIMPLIFY-CFG-LABEL: sil @test_infinite_loop_in_unreachable_block
+// CHECK-SIMPLIFY-CFG: bb0
+// CHECK-SIMPLIFY-CFG-NOT: bb1
+// CHECK-SIMPLIFY-CFG: end sil function 'test_infinite_loop_in_unreachable_block'
+sil @test_infinite_loop_in_unreachable_block : $@convention(method) (@guaranteed C) -> () {
+bb0(%0 : $C):
+  %1 = enum $MyOptional<C>, #MyOptional.some!enumelt.1, %0 : $C
+  %2 = integer_literal $Builtin.Int64, 0 
+  strong_retain %0 : $C
+  release_value %1 : $MyOptional<C>
+  %6 = integer_literal $Builtin.Int1, -1
+  cond_br %6, bb5, bb1
+
+bb1:
+  %8 = enum $MyOptional<C>, #MyOptional.some!enumelt.1, %0 : $C
+  strong_retain %0 : $C
+  br bb2(%8 : $MyOptional<C>)
+
+bb2(%11 : $MyOptional<C>):
+  %12 = unchecked_enum_data %11 : $MyOptional<C>, #MyOptional.some!enumelt.1
+  %13 = ref_element_addr %12 : $C, #C.this
+  %14 = load %13 : $*MyOptional<C>
+  switch_enum %14 : $MyOptional<C>, case #MyOptional.some!enumelt.1: bb3, case #MyOptional.none!enumelt: bb4
+
+bb3(%16 : $C):
+  retain_value %14 : $MyOptional<C>
+  release_value %11 : $MyOptional<C>
+  br bb2(%14 : $MyOptional<C>)
+
+bb4:
+  release_value %11 : $MyOptional<C>
+  br bb5
+
+bb5:
+  %22 = tuple ()
+  return %22 : $()
+} // end sil function 'test_infinite_loop_in_unreachable_block'