add comments on callbr region handling and fix polly test

Author: ro-i

llvm/include/llvm/Analysis/RegionInfoImpl.h

@@ -553,6 +553,9 @@ bool RegionInfoBase<Tr>::isRegion(BlockT *entry, BlockT *exit) const {
 
   using DST = typename DomFrontierT::DomSetType;
 
+  // Make sure that a region involving a callbr contains every successor
+  // blocks up to the ones that postdominate the callbr block. Otherwise,
+  // StructurizeCFG will tear the callbr apart.
   // TODO? post domination frontier?
   if constexpr (std::is_same_v<BlockT, BasicBlock>) {
     if (DomTreeNodeT *PDTNode = PDT->getNode(exit); PDTNode) {

polly/test/ScopDetect/callbr.ll

@@ -1,10 +1,7 @@
-; RUN: opt %loadNPMPolly '-passes=print<polly-detect>' -polly-detect-track-failures -disable-output -pass-remarks-missed=polly-detect < %s 2>&1 | FileCheck %s --check-prefix=REMARK
-; RUN: opt %loadNPMPolly '-passes=print<polly-detect>' -polly-detect-track-failures -disable-output -stats                            < %s 2>&1 | FileCheck %s --check-prefix=STAT
-; REQUIRES: asserts
+; RUN: opt %loadNPMPolly '-passes=print<polly-detect>' -disable-output < %s 2>&1 | FileCheck %s
 
-; REMARK: Branch from indirect terminator.
-
-; STAT: 1 polly-detect - Number of rejected regions: Branch from indirect terminator
+; CHECK-LABEL: func
+; CHECK-NOT: Valid
 
 
 target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"