Merge pull request #67391 from eeckstein/fix-stack-promotion-5.9

[5.9] StackPromotion: fix a crash due to a problem in liferange evaluation

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/StackPromotion.swift

@@ -268,14 +268,13 @@ private extension BasicBlockRange {
   /// Returns true if there is a direct edge connecting this range with the `otherRange`.
   func hasControlFlowEdge(to otherRange: BasicBlockRange) -> Bool {
     func isOnlyInOtherRange(_ block: BasicBlock) -> Bool {
-      return !inclusiveRangeContains(block) &&
-             otherRange.inclusiveRangeContains(block) && block != otherRange.begin
+      return !inclusiveRangeContains(block) && otherRange.inclusiveRangeContains(block)
     }
 
     for lifeBlock in inclusiveRange {
       assert(otherRange.inclusiveRangeContains(lifeBlock), "range must be a subset of other range")
       for succ in lifeBlock.successors {
-        if isOnlyInOtherRange(succ) {
+        if isOnlyInOtherRange(succ) && succ != otherRange.begin {
           return true
         }
         // The entry of the begin-block is conceptually not part of the range. We can check if

test/SILOptimizer/stack_promotion.sil

@@ -1156,3 +1156,28 @@ bb0(%0 : $UnownedLink):
   %r = tuple ()
   return %r : $()
 }
+
+// CHECK-LABEL: sil @inner_liferange_jumps_to_outer_in_header_block
+// CHECK:         alloc_ref $XX
+// CHECK-LABEL: } // end sil function 'inner_liferange_jumps_to_outer_in_header_block'
+sil @inner_liferange_jumps_to_outer_in_header_block : $@convention(thin) (@owned XX) -> () {
+bb0(%0 : $XX):
+  %1 = alloc_stack $XX
+  br bb1(%0 : $XX)
+
+bb1(%2 : $XX):
+  strong_release %2 : $XX
+  %4 = alloc_ref $XX
+  store %4 to %1 : $*XX
+  cond_br undef, bb2, bb3
+
+bb2:
+  br bb1(%4 : $XX)
+
+bb3:
+  strong_release %4 : $XX
+  dealloc_stack %1 : $*XX
+  %r = tuple ()
+  return %r : $()
+}
+