[PATCH] D79830: Add support of __builtin_expect_with_probability

David Li via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Tue Jun 9 09:52:34 PDT 2020


davidxl added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp:58
 
+std::pair<uint32_t, uint32_t> setBranchWeight(Intrinsic::ID IntrinsicID,
+                                              CallInst *CI, int BranchCount) {
----------------
nit: change name to  getBranchWeight or computeBranchWeight 


================
Comment at: llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp:69
+    double TrueProb = Confidence->getValueAPF().convertToDouble();
+    double FalseProb = (1.0 - TrueProb) / (BranchCount - 1);
+    uint32_t LikelyBW = ceil((TrueProb * (double)(INT32_MAX - 1)) + 1.0);
----------------
assert TrueProb is in [0,1]


================
Comment at: llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp:96
+  uint32_t LikelyBranchWeightVal = WeightNums.first;
+  uint32_t UnlikelyBranchWeightVal = WeightNums.second;
+
----------------
simpler to use tuple and tie here.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D79830/new/

https://reviews.llvm.org/D79830





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