Update for current naming conventions.

[oota-llvm.git] / lib / Support / BlockFrequency.cpp

diff --git a/lib/Support/BlockFrequency.cpp b/lib/Support/BlockFrequency.cpp
index 0bc784081042cb908711027a0a62e7c41734e4cf..84a993e3e5b6fd6a54dad76dc982b2c7ced36cf1 100644 (file)
--- a/lib/Support/BlockFrequency.cpp
+++ b/lib/Support/BlockFrequency.cpp
@@ -46,8 +46,9 @@ void mult96bit(uint64_t freq, uint32_t N, uint64_t W[2]) {
 uint64_t div96bit(uint64_t W[2], uint32_t D) {
   uint64_t y = W[0];
   uint64_t x = W[1];
+  int i;
 
-  for (int i = 1; i <= 64; ++i) {
+  for (i = 1; i <= 64 && x; ++i) {
     uint32_t t = (int)x >> 31;
     x = (x << 1) | (y >> 63);
     y = y << 1;
@@ -57,7 +58,7 @@ uint64_t div96bit(uint64_t W[2], uint32_t D) {
     }
   }
 
-  return y;
+  return y << (64 - i + 1);
 }
 
 }
@@ -69,8 +70,13 @@ BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
 
   assert(n <= d && "Probability must be less or equal to 1.");
 
-  // If we can overflow use 96-bit operations.
-  if (n > 0 && Frequency > UINT64_MAX / n) {
+  // Calculate Frequency * n.
+  uint64_t mulLo = (Frequency & UINT32_MAX) * n;
+  uint64_t mulHi = (Frequency >> 32) * n;
+  uint64_t mulRes = (mulHi << 32) + mulLo;
+
+  // If there was overflow use 96-bit operations.
+  if (mulHi > UINT32_MAX || mulRes < mulLo) {
     // 96-bit value represented as W[1]:W[0].
     uint64_t W[2];
 
@@ -81,8 +87,7 @@ BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
     return *this;
   }
 
-  Frequency *= n;
-  Frequency /= d;
+  Frequency = mulRes / d;
   return *this;
 }