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Optimize liveAt() and overlaps(). We now use a binary search instead

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of a linear search to find the first range for comparisons. This cuts
down the linear scan register allocator running time by a factor of 3
in 254.perlbmk and by a factor of 2.2 in 176.gcc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11030 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alkis Evlogimenos 2004-01-31 16:54:54 +00:00
parent 4d46e1e521
commit 97017de187
1 changed files with 30 additions and 20 deletions
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50
lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -463,22 +463,43 @@ LiveIntervals::Interval::Interval(unsigned r)
bool LiveIntervals::Interval::liveAt(unsigned index) const
{
Ranges::const_iterator r = ranges.begin();
while (r != ranges.end() && index < (r->second - 1)) {
if (index >= r->first)
return true;
++r;
}
return false;
Range dummy(index, index+1);
Ranges::const_iterator r = std::upper_bound(ranges.begin(),
ranges.end(),
dummy);
if (r == ranges.begin())
return false;
--r;
return index >= r->first && index < (r->second - 1);
}
bool LiveIntervals::Interval::overlaps(const Interval& other) const
{
Ranges::const_iterator i = ranges.begin();
Ranges::const_iterator ie = ranges.end();
Ranges::const_iterator j = other.ranges.begin();
Ranges::const_iterator je = other.ranges.end();
if (i->first < j->first) {
i = std::upper_bound(i, ie, *j);
if (i != ranges.begin()) --i;
}
else if (j->first < i->first) {
j = std::upper_bound(j, je, *i);
if (j != other.ranges.begin()) --j;
}
while (i != ie && j != je) {
if (i->first == j->first) {
return true;
}
else {
if (i->first > j->first) {
swap(i, j);
swap(ie, je);
}
assert(i->first < j->first);
while (i != ranges.end() && j != other.ranges.end()) {
if (i->first < j->first) {
if ((i->second - 1) > j->first) {
return true;
}
@ -486,17 +507,6 @@ bool LiveIntervals::Interval::overlaps(const Interval& other) const
++i;
}
}
else if (j->first < i->first) {
if ((j->second - 1) > i->first) {
return true;
}
else {
++j;
}
}
else {
return true;
}
}
return false;