[PATCH] D43256: [MBP] Move a latch block with conditional exit and multi predecessors to top of loop

[Guozhi Wei via Phabricator via llvm-commits]

Carrot added a comment.

ebrevnov, with following patch the test case can be layout correctly. Can you try it with your actual code?

Index: BranchProbabilityInfo.cpp
================================

- BranchProbabilityInfo.cpp	(revision 366821)

+++ BranchProbabilityInfo.cpp	(working copy)
@@ -118,6 +118,12 @@
 static const uint32_t FPH_TAKEN_WEIGHT = 20;
 static const uint32_t FPH_NONTAKEN_WEIGHT = 12;

+/// This is the probability for an ordered floating point comparison.
+static const uint32_t FPH_ORD_WEIGHT = 1024 * 1024 - 1;
+/// This is the probability for an unordered floating point comparison, it means
+/// one or two of the operands are NaN, it should be extremely rare.
+static const uint32_t FPH_UNO_WEIGHT = 1;
+
 /// Invoke-terminating normal branch taken weight
 ///
 /// This is the weight for branching to the normal destination of an invoke
@@ -778,6 +784,8 @@

  if (!FCmp)
    return false;
   

+  uint32_t TakenWeight = FPH_TAKEN_WEIGHT;
+  uint32_t NontakenWeight = FPH_NONTAKEN_WEIGHT;

  bool isProb;
  if (FCmp->isEquality()) {
    // f1 == f2 -> Unlikely

@@ -786,9 +794,13 @@

  } else if (FCmp->getPredicate() == FCmpInst::FCMP_ORD) {
    // !isnan -> Likely
    isProb = true;

+    TakenWeight = FPH_ORD_WEIGHT;
+    NontakenWeight = FPH_UNO_WEIGHT;

  } else if (FCmp->getPredicate() == FCmpInst::FCMP_UNO) {
    // isnan -> Unlikely
    isProb = false;

+    TakenWeight = FPH_ORD_WEIGHT;
+    NontakenWeight = FPH_UNO_WEIGHT;

  } else {
    return false;
  }

@@ -798,8 +810,7 @@

  if (!isProb)
    std::swap(TakenIdx, NonTakenIdx);
   

- BranchProbability TakenProb(FPH_TAKEN_WEIGHT,
- FPH_TAKEN_WEIGHT + FPH_NONTAKEN_WEIGHT);

+  BranchProbability TakenProb(TakenWeight, TakenWeight + NontakenWeight);

  setEdgeProbability(BB, TakenIdx, TakenProb);
  setEdgeProbability(BB, NonTakenIdx, TakenProb.getCompl());
  return true;


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D43256/new/

https://reviews.llvm.org/D43256