[PATCH] D26784: [LoopUnroll] Move code to exit early. NFC.

[Haicheng Wu via llvm-commits]

haicheng created this revision.
haicheng added a reviewer: mzolotukhin.
haicheng added a subscriber: llvm-commits.
haicheng set the repository for this revision to rL LLVM.
Herald added a subscriber: mcrosier.

Just to save some compilation time if possible.


Repository:
  rL LLVM

https://reviews.llvm.org/D26784

Files:
  lib/Transforms/Scalar/LoopUnrollPass.cpp


Index: lib/Transforms/Scalar/LoopUnrollPass.cpp
===================================================================
--- lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -932,7 +932,11 @@
                             Optional<bool> ProvidedUpperBound) {
   DEBUG(dbgs() << "Loop Unroll: F[" << L->getHeader()->getParent()->getName()
                << "] Loop %" << L->getHeader()->getName() << "\n");
-  if (HasUnrollDisablePragma(L)) {
+  if (HasUnrollDisablePragma(L)) 
+    return false;
+  if (!L->isLoopSimplifyForm()) { 
+    DEBUG(
+        dbgs() << "  Not unrolling loop which is not in loop-simplify form.\n");
     return false;
   }
 
@@ -942,6 +946,9 @@
   TargetTransformInfo::UnrollingPreferences UP = gatherUnrollingPreferences(
       L, TTI, ProvidedThreshold, ProvidedCount, ProvidedAllowPartial,
       ProvidedRuntime, ProvidedUpperBound);
+  // Exit early if unrolling is disabled.
+  if (UP.Threshold == 0 && (!UP.Partial || UP.PartialThreshold == 0))
+    return false;
   unsigned LoopSize = ApproximateLoopSize(
       L, NumInlineCandidates, NotDuplicatable, Convergent, TTI, &AC, UP.BEInsns);
   DEBUG(dbgs() << "  Loop Size = " << LoopSize << "\n");
@@ -954,11 +961,6 @@
     DEBUG(dbgs() << "  Not unrolling loop with inlinable calls.\n");
     return false;
   }
-  if (!L->isLoopSimplifyForm()) {
-    DEBUG(
-        dbgs() << "  Not unrolling loop which is not in loop-simplify form.\n");
-    return false;
-  }
 
   // Find trip count and trip multiple if count is not available
   unsigned TripCount = 0;
@@ -975,10 +977,6 @@
     TripMultiple = SE->getSmallConstantTripMultiple(L, ExitingBlock);
   }
 
-  // Exit early if unrolling is disabled.
-  if (UP.Threshold == 0 && (!UP.Partial || UP.PartialThreshold == 0))
-    return false;
-
   // If the loop contains a convergent operation, the prelude we'd add
   // to do the first few instructions before we hit the unrolled loop
   // is unsafe -- it adds a control-flow dependency to the convergent


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