[llvm] 0be9940 - [SCEV] Don't check if propagation safe if there are no flags (NFC)

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2021-10-05T22:25:41+02:00
New Revision: 0be9940ef240d04111c7ef7df360c3b4209dfdea

URL: https://github.com/llvm/llvm-project/commit/0be9940ef240d04111c7ef7df360c3b4209dfdea
DIFF: https://github.com/llvm/llvm-project/commit/0be9940ef240d04111c7ef7df360c3b4209dfdea.diff

LOG: [SCEV] Don't check if propagation safe if there are no flags (NFC)

If there are no nowrap flags, then we don't need to determine
whether propagating flags is safe -- it will make no difference.

Added: 
    

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp

Removed: 
    


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diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index c09180b2c197..6683b1a5205c 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -2802,11 +2802,13 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
       // Proving that entry to the outer scope neccesitates entry to the inner
       // scope, thus proves the program undefined if the flags would be violated
       // in the outer scope.
-      auto *DefI = getDefiningScopeBound(LIOps);
-      auto *ReachI = &*AddRecLoop->getHeader()->begin();
-      const bool CanPropagateFlags =
-        isGuaranteedToTransferExecutionTo(DefI, ReachI);
-      auto AddFlags = CanPropagateFlags ? Flags : SCEV::FlagAnyWrap;
+      SCEV::NoWrapFlags AddFlags = Flags;
+      if (AddFlags != SCEV::FlagAnyWrap) {
+        auto *DefI = getDefiningScopeBound(LIOps);
+        auto *ReachI = &*AddRecLoop->getHeader()->begin();
+        if (!isGuaranteedToTransferExecutionTo(DefI, ReachI))
+          AddFlags = SCEV::FlagAnyWrap;
+      }
       AddRecOps[0] = getAddExpr(LIOps, AddFlags, Depth + 1);
 
       // Build the new addrec. Propagate the NUW and NSW flags if both the