[SCEV] When printing via -analysis, dump loop disposition

There are currently some bugs in tree around SCEV caching an incorrect
loop disposition.  Printing out loop dispositions will let us write
whitebox tests as those are fixed.

The dispositions are printed as a list in "inside out" order,
i.e. innermost loop first.

llvm-svn: 268177

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index cfb9f5e24b2..99c6500e5fc 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -9565,6 +9565,17 @@ static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
   OS << "\n";
 }
 
+static StringRef loopDispositionToStr(ScalarEvolution::LoopDisposition LD) {
+  switch (LD) {
+  case ScalarEvolution::LoopVariant:
+    return "Variant";
+  case ScalarEvolution::LoopInvariant:
+    return "Invariant";
+  case ScalarEvolution::LoopComputable:
+    return "Computable";
+  }
+}
+
 void ScalarEvolution::print(raw_ostream &OS) const {
   // ScalarEvolution's implementation of the print method is to print
   // out SCEV values of all instructions that are interesting. Doing
@@ -9612,6 +9623,20 @@ void ScalarEvolution::print(raw_ostream &OS) const {
         } else {
           OS << *ExitValue;
         }
+
+        bool First = true;
+        for (auto *Iter = L; Iter; Iter = Iter->getParentLoop()) {
+          if (First) {
+            OS << "\t\t" "LoopDispositions: [ ";
+            First = false;
+          } else {
+            OS << ", ";
+          }
+
+          OS << loopDispositionToStr(SE.getLoopDisposition(SV, Iter));
+        }
+
+        OS << " ]";
       }
 
       OS << "\n";