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-rw-r--r--lib/Support/BlockFrequency.cpp95
1 files changed, 2 insertions, 93 deletions
diff --git a/lib/Support/BlockFrequency.cpp b/lib/Support/BlockFrequency.cpp
index 00cf75bd5c..6f7e341904 100644
--- a/lib/Support/BlockFrequency.cpp
+++ b/lib/Support/BlockFrequency.cpp
@@ -18,94 +18,8 @@
using namespace llvm;
-/// Multiply FREQ by N and store result in W array.
-static void mult96bit(uint64_t freq, uint32_t N, uint32_t W[3]) {
- uint64_t u0 = freq & UINT32_MAX;
- uint64_t u1 = freq >> 32;
-
- // Represent 96-bit value as W[2]:W[1]:W[0];
- uint64_t t = u0 * N;
- uint64_t k = t >> 32;
- W[0] = t;
- t = u1 * N + k;
- W[1] = t;
- W[2] = t >> 32;
-}
-
-/// Divide 96-bit value stored in W[2]:W[1]:W[0] by D. Since our word size is a
-/// 32 bit unsigned integer, we can use a short division algorithm.
-static uint64_t divrem96bit(uint32_t W[3], uint32_t D, uint32_t *Rout) {
- // We assume that W[2] is non-zero since if W[2] is not then the user should
- // just use hardware division.
- assert(W[2] && "This routine assumes that W[2] is non-zero since if W[2] is "
- "zero, the caller should just use 64/32 hardware.");
- uint32_t Q[3] = { 0, 0, 0 };
-
- // The generalized short division algorithm sets i to m + n - 1, where n is
- // the number of words in the divisior and m is the number of words by which
- // the divident exceeds the divisor (i.e. m + n == the length of the dividend
- // in words). Due to our assumption that W[2] is non-zero, we know that the
- // dividend is of length 3 implying since n is 1 that m = 2. Thus we set i to
- // m + n - 1 = 2 + 1 - 1 = 2.
- uint32_t R = 0;
- for (int i = 2; i >= 0; --i) {
- uint64_t PartialD = uint64_t(R) << 32 | W[i];
- if (PartialD == 0) {
- Q[i] = 0;
- R = 0;
- } else if (PartialD < D) {
- Q[i] = 0;
- R = uint32_t(PartialD);
- } else if (PartialD == D) {
- Q[i] = 1;
- R = 0;
- } else {
- Q[i] = uint32_t(PartialD / D);
- R = uint32_t(PartialD - (Q[i] * D));
- }
- }
-
- // If Q[2] is non-zero, then we overflowed.
- uint64_t Result;
- if (Q[2]) {
- Result = UINT64_MAX;
- R = D;
- } else {
- // Form the final uint64_t result, avoiding endianness issues.
- Result = uint64_t(Q[0]) | (uint64_t(Q[1]) << 32);
- }
-
- if (Rout)
- *Rout = R;
-
- return Result;
-}
-
-uint32_t BlockFrequency::scale(uint32_t N, uint32_t D) {
- assert(D != 0 && "Division by zero");
-
- // Calculate Frequency * N.
- uint64_t MulLo = (Frequency & UINT32_MAX) * N;
- uint64_t MulHi = (Frequency >> 32) * N;
- uint64_t MulRes = (MulHi << 32) + MulLo;
-
- // If the product fits in 64 bits, just use built-in division.
- if (MulHi <= UINT32_MAX && MulRes >= MulLo) {
- Frequency = MulRes / D;
- return MulRes % D;
- }
-
- // Product overflowed, use 96-bit operations.
- // 96-bit value represented as W[2]:W[1]:W[0].
- uint32_t W[3];
- uint32_t R;
- mult96bit(Frequency, N, W);
- Frequency = divrem96bit(W, D, &R);
- return R;
-}
-
BlockFrequency &BlockFrequency::operator*=(const BranchProbability &Prob) {
- scale(Prob.getNumerator(), Prob.getDenominator());
+ Frequency = Prob.scale(Frequency);
return *this;
}
@@ -117,7 +31,7 @@ BlockFrequency::operator*(const BranchProbability &Prob) const {
}
BlockFrequency &BlockFrequency::operator/=(const BranchProbability &Prob) {
- scale(Prob.getDenominator(), Prob.getNumerator());
+ Frequency = Prob.scaleByInverse(Frequency);
return *this;
}
@@ -156,8 +70,3 @@ BlockFrequency &BlockFrequency::operator>>=(const unsigned count) {
Frequency |= Frequency == 0;
return *this;
}
-
-uint32_t BlockFrequency::scale(const BranchProbability &Prob) {
- return scale(Prob.getNumerator(), Prob.getDenominator());
-}
-