Merge pull request swiftlang#23118 from shajrawi/stack_promote_fix

Author: swift-ci

lib/SIL/BasicBlockUtils.cpp

@@ -50,8 +50,10 @@ void swift::changeBranchTarget(TermInst *T, unsigned edgeIdx,
   case TermKind::BranchInst: {
     auto *BI = cast<BranchInst>(T);
     SmallVector<SILValue, 8> args;
-    for (auto arg : BI->getArgs())
-      args.push_back(arg);
+    if (preserveArgs) {
+      for (auto arg : BI->getArgs())
+        args.push_back(arg);
+    }
     B.createBranch(T->getLoc(), newDest, args);
     BI->dropAllReferences();
     BI->eraseFromParent();

test/SILOptimizer/stack_promotion.sil

@@ -741,3 +741,82 @@ bb0(%0 : $Int, %another: $Array<Int>):
   %24 = tuple ()
   return %24 : $()
 }
+
+
+// CHECK-LABEL: sil @promote_with_unreachable_block_nest_bug
+// CHECK: bb3:
+// CHECK: dealloc_ref [stack] %{{.*}}
+// CHECK: bb4:
+// CHECK: br bb5
+// CHECK: bb5:
+// CHECK: dealloc_ref [stack] %{{.*}}
+// CHECK: bb6:
+// CHECK: dealloc_ref [stack] %{{.*}}
+// CHECK: bb11:
+// CHECK: alloc_ref [stack] $XX
+// CHECK: return
+sil @promote_with_unreachable_block_nest_bug : $@convention(thin) () -> Int32 {
+bb0:
+  %0 = alloc_stack $Builtin.Int32                 // user: %30
+  %1 = alloc_stack $Builtin.Int32                 // users: %29, %27
+  cond_br undef, bb1, bb7                         // id: %2
+
+bb1:                                              // Preds: bb0
+  br bb14                                         // id: %3
+
+bb2:                                              // Preds: bb10
+  cond_br undef, bb5, bb3                         // id: %4
+
+bb3:                                              // Preds: bb2
+  strong_release %20 : $XX                        // id: %5
+  br bb6                                          // id: %6
+
+bb4:                                              // Preds: bb10
+  %7 = integer_literal $Builtin.Int32, 0          // user: %8
+  %8 = struct $Int32 (%7 : $Builtin.Int32)        // user: %9
+  br bb13(%8 : $Int32)                            // id: %9
+
+bb5:                                              // Preds: bb2
+  strong_release %20 : $XX                        // id: %10
+  br bb6                                          // id: %11
+
+bb6:                                              // Preds: bb5 bb3
+  br bb12                                         // id: %12
+
+bb7:                                              // Preds: bb0
+  cond_br undef, bb8, bb9                         // id: %13
+
+bb8:                                              // Preds: bb7
+  cond_br undef, bb10, bb11                       // id: %14
+
+bb9:                                              // Preds: bb7
+  %15 = integer_literal $Builtin.Int32, 0         // user: %16
+  %16 = struct $Int32 (%15 : $Builtin.Int32)      // user: %17
+  br bb13(%16 : $Int32)                           // id: %17
+
+bb10:                                             // Preds: bb8
+  %18 = alloc_ref $XX                             // user: %20
+  // function_ref xx_init
+  %19 = function_ref @xx_init : $@convention(thin) (@guaranteed XX) -> XX // user: %20
+  %20 = apply %19(%18) : $@convention(thin) (@guaranteed XX) -> XX // users: %21, %5, %10
+  %21 = ref_element_addr %20 : $XX, #XX.x         // user: %22
+  %22 = load %21 : $*Int32
+  cond_br undef, bb2, bb4                         // id: %23
+
+bb11:                                             // Preds: bb8
+  unreachable                                     // id: %24
+
+bb12:                                             // Preds: bb6
+  br bb14                                         // id: %25
+
+bb13(%26 : $Int32):                               // Preds: bb9 bb4
+  dealloc_stack %1 : $*Builtin.Int32              // id: %27
+  unreachable                                     // id: %28
+
+bb14:                                             // Preds: bb12 bb1
+  dealloc_stack %1 : $*Builtin.Int32              // id: %29
+  dealloc_stack %0 : $*Builtin.Int32              // id: %30
+  %31 = integer_literal $Builtin.Int32, 0         // user: %32
+  %32 = struct $Int32 (%31 : $Builtin.Int32)      // user: %33
+  return %32 : $Int32                             // id: %33
+} // end sil function 'promote_with_unreachable_block_nest_bug'