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Optimize 96-bit division a little bit.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136222 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakub Staszak 2011-07-27 16:00:40 +00:00
parent 636a02b57c
commit ffcc2a542c
1 changed files with 3 additions and 2 deletions

5
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);
}
}