From: Chandler Carruth <chandlerc@gmail.com>
Date: Fri, 13 Feb 2015 04:06:08 +0000 (+0000)
Subject: [unroll] Replace a linear time check for no uses with a constant time
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=2640fd5bae01dfdb7d07178c0a71cdbf8a519db6;hp=6a1227657333bf6a38924cda18d4b3bc677fc560;p=oota-llvm.git

[unroll] Replace a linear time check for no uses with a constant time
check.

Also hoist this into the enqueue process as it is faster even than
testing the worklist set, we should just directly filter these out much
like we filter out constants and such.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229056 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/LoopUnrollPass.cpp b/lib/Transforms/Scalar/LoopUnrollPass.cpp
index d1daaa684ad..37851ba87da 100644
--- a/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -519,7 +519,8 @@ public:
     auto EnqueueOperands = [&](Instruction &I) {
       for (auto *Op : I.operand_values())
         if (auto *OpI = dyn_cast<Instruction>(Op))
-          Worklist.insert(OpI);
+          if (!OpI->use_empty())
+            Worklist.insert(OpI);
     };
 
     // Start by initializing worklist with simplified instructions.
@@ -541,8 +542,6 @@ public:
         continue;
       if (DeadInstructions.count(I))
         continue;
-      if (I->getNumUses() == 0)
-        continue;
       bool AllUsersFolded = true;
       for (User *U : I->users()) {
         Instruction *UI = dyn_cast<Instruction>(U);