[PATCH] D19950: Use frequency info to guide Loop Invariant Code Motion.

[Jun Bum Lim via llvm-commits]

junbuml added inline comments.

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Comment at: include/llvm/Transforms/Utils/LoopUtils.h:354-360
@@ -352,8 +353,9 @@
 
 /// \brief Walk the specified region of the CFG (defined by all blocks
 /// dominated by the specified block, and that are in the current loop) in depth
 /// first order w.r.t the DominatorTree.  This allows us to visit definitions
 /// before uses, allowing us to hoist a loop body in one pass without iteration.
 /// Takes DomTreeNode, AliasAnalysis, LoopInfo, DominatorTree, DataLayout,
 /// TargetLibraryInfo, Loop, AliasSet information for all instructions of the
 /// loop and loop safety information as arguments. It returns changed status.
+bool hoistRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *,
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Please update the comment.

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Comment at: lib/Transforms/Scalar/LICM.cpp:353-355
@@ -346,3 +352,5 @@
   bool Changed = false;
-  if (!inSubLoop(BB, CurLoop, LI))
+  if (!inSubLoop(BB, CurLoop, LI)) {
+    bool ShouldHoist =
+        BFI->getBlockFreq(BB) >= BFI->getBlockFreq(CurLoop->getLoopPreheader());
     for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;) {
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I agree that we still need to perform constant folding even when ShouldHoist is false?


http://reviews.llvm.org/D19950