RegionInfo: Correctly expand regions

Instead of playing around with dominance to verify if the possible expansion of
a scop region is indeed a single entry single exit region, we now distinguish
two cases. In case we only append a basic block, all edges entering this basic
block need to have come from within the region that is expanded. In case we join
two regions, the source basic blocks of the edges that end at the entry node of
the region that is appended most be part of either the original region or the
region that is appended.

This change will be tested through Polly.

This fixes llvm.org/PR25242

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@251267 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/RegionInfoImpl.h b/include/llvm/Analysis/RegionInfoImpl.h
index 0598068d69d340b4d9c75ce7b47a97d73a74fb3b..134cd8f96fbeabc72bc00bbd346d46bc90180c2a 100644 (file)
--- a/include/llvm/Analysis/RegionInfoImpl.h
+++ b/include/llvm/Analysis/RegionInfoImpl.h
@@ -444,16 +444,14 @@ typename Tr::RegionT *RegionBase<Tr>::getExpandedRegion() const {
   if (NumSuccessors == 0)
     return nullptr;
 
-  for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
-                  PE = InvBlockTraits::child_end(getExit());
-       PI != PE; ++PI) {
-    if (!DT->dominates(getEntry(), *PI))
-      return nullptr;
-  }
-
   RegionT *R = RI->getRegionFor(exit);
 
   if (R->getEntry() != exit) {
+    for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
+                    PE = InvBlockTraits::child_end(getExit());
+         PI != PE; ++PI)
+      if (!contains(*PI))
+        return nullptr;
     if (Tr::getNumSuccessors(exit) == 1)
       return new RegionT(getEntry(), *BlockTraits::child_begin(exit), RI, DT);
     return nullptr;
@@ -462,13 +460,11 @@ typename Tr::RegionT *RegionBase<Tr>::getExpandedRegion() const {
   while (R->getParent() && R->getParent()->getEntry() == exit)
     R = R->getParent();
 
-  if (!DT->dominates(getEntry(), R->getExit())) {
-    for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
-                    PE = InvBlockTraits::child_end(getExit());
-         PI != PE; ++PI) {
-      if (!DT->dominates(R->getExit(), *PI))
-        return nullptr;
-    }
+  for (PredIterTy PI = InvBlockTraits::child_begin(getExit()),
+                  PE = InvBlockTraits::child_end(getExit());
+       PI != PE; ++PI) {
+    if (!(contains(*PI) || R->contains(*PI)))
+      return nullptr;
   }
 
   return new RegionT(getEntry(), R->getExit(), RI, DT);