[PM] Teach LoopUnroll to update the LPM infrastructure as it unrolls

loops.

We do this by reconstructing the newly added loops after the unroll
completes to avoid threading pass manager details through all the mess
of the unrolling infrastructure.

I've enabled some extra assertions in the LPM to try and catch issues
here and enabled a bunch of unroller tests to try and make sure this is
sane.

Currently, I'm manually running loop-simplify when needed. That should
go away once it is folded into the LPM infrastructure.

Differential Revision: https://reviews.llvm.org/D28848

llvm-svn: 293011

1 files changed, 7 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopPassManager.cpp b/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
index 028f4bba8b1..10f6fcdcfdb 100644
--- a/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopPassManager.cpp
@@ -42,6 +42,13 @@ PassManager<Loop, LoopAnalysisManager, LoopStandardAnalysisResults &,
       break;
     }
 
+#ifndef NDEBUG
+    // Verify the loop structure and LCSSA form before visiting the loop.
+    L.verifyLoop();
+    assert(L.isRecursivelyLCSSAForm(AR.DT, AR.LI) &&
+           "Loops must remain in LCSSA form!");
+#endif
+
     // Update the analysis manager as each pass runs and potentially
     // invalidates analyses.
     AM.invalidate(L, PassPA);