[llvm] r278854 - [LoopUnroll] Don't clear out the AssumptionCache on each loop

[David Majnemer via llvm-commits]

Author: majnemer
Date: Tue Aug 16 16:09:46 2016
New Revision: 278854

URL: http://llvm.org/viewvc/llvm-project?rev=278854&view=rev
Log:
[LoopUnroll] Don't clear out the AssumptionCache on each loop

Clearing out the AssumptionCache can cause us to rescan the entire
function for assumes.  If there are many loops, then we are scanning
over the entire function many times.

Instead of clearing out the AssumptionCache, register all cloned
assumes.

Modified:
    llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp

Modified: llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp?rev=278854&r1=278853&r2=278854&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopUnroll.cpp Tue Aug 16 16:09:46 2016
@@ -28,6 +28,7 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Dominators.h"
+#include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
@@ -486,9 +487,14 @@ bool llvm::UnrollLoop(Loop *L, unsigned
     }
 
     // Remap all instructions in the most recent iteration
-    for (BasicBlock *NewBlock : NewBlocks)
-      for (Instruction &I : *NewBlock)
+    for (BasicBlock *NewBlock : NewBlocks) {
+      for (Instruction &I : *NewBlock) {
         ::remapInstruction(&I, LastValueMap);
+        if (auto *II = dyn_cast<IntrinsicInst>(&I))
+          if (II->getIntrinsicID() == Intrinsic::assume)
+            AC->registerAssumption(II);
+      }
+    }
   }
 
   // Loop over the PHI nodes in the original block, setting incoming values.
@@ -601,10 +607,6 @@ bool llvm::UnrollLoop(Loop *L, unsigned
     }
   }
 
-  // FIXME: We could register any cloned assumptions instead of clearing the
-  // whole function's cache.
-  AC->clear();
-
   // FIXME: We only preserve DT info for complete unrolling now. Incrementally
   // updating domtree after partial loop unrolling should also be easy.
   if (DT && !CompletelyUnroll)