1 files changed, 51 insertions, 5 deletions
diff --git a/llvm/lib/Support/BranchProbability.cpp b/llvm/lib/Support/BranchProbability.cpp
index 65878d6e3..47b06c2 100644
--- a/llvm/lib/Support/BranchProbability.cpp
+++ b/llvm/lib/Support/BranchProbability.cpp
@@ -15,17 +15,63 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/raw_ostream.h"
+#include <cassert>
 
 using namespace llvm;
 
 raw_ostream &BranchProbability::print(raw_ostream &OS) const {
-  return OS << N << " / " << D << " = "
-            << format("%g%%", ((double)N / D) * 100.0);
+  auto GetHexDigit = [](int Val) -> char {
+    assert(Val < 16);
+    if (Val < 10)
+      return '0' + Val;
+    return 'a' + Val - 10;
+  };
+  OS << "0x";
+  for (int Digits = 0; Digits < 8; ++Digits)
+    OS << GetHexDigit(N >> (28 - Digits * 4) & 0xf);
+  OS << " / 0x";
+  for (int Digits = 0; Digits < 8; ++Digits)
+    OS << GetHexDigit(D >> (28 - Digits * 4) & 0xf);
+  OS << " = " << format("%.2f%%", ((double)N / D) * 100.0);
+  return OS;
 }
 
 void BranchProbability::dump() const { print(dbgs()) << '\n'; }
 
-static uint64_t scale(uint64_t Num, uint32_t N, uint32_t D) {
+BranchProbability::BranchProbability(uint32_t Numerator, uint32_t Denominator) {
+  assert(Denominator > 0 && "Denominator cannot be 0!");
+  assert(Numerator <= Denominator && "Probability cannot be bigger than 1!");
+  if (Denominator == D)
+    N = Numerator;
+  else {
+    uint64_t Prob64 =
+        (Numerator * static_cast<uint64_t>(D) + Denominator / 2) / Denominator;
+    N = static_cast<uint32_t>(Prob64);
+  }
+}
+
+BranchProbability &BranchProbability::operator+=(BranchProbability RHS) {
+  assert(N <= D - RHS.N &&
+         "The sum of branch probabilities should not exceed one!");
+  N += RHS.N;
+  return *this;
+}
+
+BranchProbability &BranchProbability::operator-=(BranchProbability RHS) {
+  assert(N >= RHS.N &&
+         "Can only subtract a smaller probability from a larger one!");
+  N -= RHS.N;
+  return *this;
+}
+
+// If ConstD is not zero, then replace D by ConstD so that division and modulo
+// operations by D can be optimized, in case this function is not inlined by the
+// compiler.
+template <uint32_t ConstD>
+inline uint64_t scale(uint64_t Num, uint32_t N, uint32_t D) {
+  if (ConstD > 0)
+    D = ConstD;
+
   assert(D && "divide by 0");
 
   // Fast path for multiplying by 1.0.
@@ -65,9 +111,9 @@ static uint64_t scale(uint64_t Num, uint32_t N, uint32_t D) {
 }
 
 uint64_t BranchProbability::scale(uint64_t Num) const {
-  return ::scale(Num, N, D);
+  return ::scale<D>(Num, N, D);
 }
 
 uint64_t BranchProbability::scaleByInverse(uint64_t Num) const {
-  return ::scale(Num, D, N);
+  return ::scale<0>(Num, D, N);
 }