[llvm-commits] [llvm] r142687 - /llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp

[Benjamin Kramer]

Author: d0k
Date: Fri Oct 21 16:13:47 2011
New Revision: 142687

URL: http://llvm.org/viewvc/llvm-project?rev=142687&view=rev
Log:
Extend the floating point heuristic to consider NaN checks unlikely.

Modified:
    llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp

Modified: llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp?rev=142687&r1=142686&r2=142687&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/BranchProbabilityInfo.cpp Fri Oct 21 16:13:47 2011
@@ -391,15 +391,28 @@
 
   Value *Cond = BI->getCondition();
   FCmpInst *FCmp = dyn_cast<FCmpInst>(Cond);
-  if (!FCmp || !FCmp->isEquality())
+  if (!FCmp)
     return false;
 
+  bool isProb;
+  if (FCmp->isEquality()) {
+    // f1 == f2 -> Unlikely
+    // f1 != f2 -> Likely
+    isProb = !FCmp->isTrueWhenEqual();
+  } else if (FCmp->getPredicate() == FCmpInst::FCMP_ORD) {
+    // !isnan -> Likely
+    isProb = true;
+  } else if (FCmp->getPredicate() == FCmpInst::FCMP_UNO) {
+    // isnan -> Unlikely
+    isProb = false;
+  } else {
+    return false;
+  }
+
   BasicBlock *Taken = BI->getSuccessor(0);
   BasicBlock *NonTaken = BI->getSuccessor(1);
 
-  // f1 == f2 -> Unlikely
-  // f1 != f2 -> Likely
-  if (FCmp->isTrueWhenEqual())
+  if (!isProb)
     std::swap(Taken, NonTaken);
 
   BP->setEdgeWeight(BB, Taken, FPH_TAKEN_WEIGHT);