Support: Add BranchProbability::scale() and ::scaleByInverse()

Add API to `BranchProbability` for scaling big integers.  Next job is to
rip the logic out of `BlockMass` and `BlockFrequency`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207544 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 24 insertions, 0 deletions

diff --git a/include/llvm/Support/BranchProbability.h b/include/llvm/Support/BranchProbability.h
index bf6b01defa..74d64194cf 100644
--- a/include/llvm/Support/BranchProbability.h
+++ b/include/llvm/Support/BranchProbability.h
@@ -50,6 +50,30 @@ public:
 
   void dump() const;
 
+  /// \brief Scale a large integer.
+  ///
+  /// Scales \c Num.  Guarantees full precision.  Returns the floor of the
+  /// result.
+  ///
+  /// \return \c Num times \c this.
+  ///
+  /// \note This code should be shared with (or replaced by) the implementation
+  /// of \a BlockFrequency::scale(), which seems to be calculating something
+  /// similar.
+  uint64_t scale(uint64_t Num) const;
+
+  /// \brief Scale a large integer by the inverse.
+  ///
+  /// Scales \c Num by the inverse of \c this.  Guarantees full precision.
+  /// Returns the floor of the result.
+  ///
+  /// \return \c Num divided by \c this.
+  ///
+  /// \note This code should be shared with (or replaced by) the implementation
+  /// of \a BlockFrequency::scale(), which seems to be calculating something
+  /// similar.
+  uint64_t scaleByInverse(uint64_t Num) const;
+
   bool operator==(BranchProbability RHS) const {
     return (uint64_t)N * RHS.D == (uint64_t)D * RHS.N;
   }