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Add a new llcbeta option. This speeds up viterbi from 12.34 to 8.76s on

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X86.  If happy, I'll enable this by default.

llvm-svn: 31493
This commit is contained in:
Chris Lattner 2006-11-07 07:18:40 +00:00
parent 78c84a0328
commit 01d039cc44
1 changed files with 19 additions and 4 deletions
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23
llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -59,6 +59,9 @@ namespace {
EnableJoining("join-liveintervals",
cl::desc("Coallesce copies (default=true)"),
cl::init(true));
static cl::opt<bool>
EnableReweight("enable-majik-f00");
}
void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const {
@ -208,14 +211,26 @@ bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
}
}
for (iterator I = begin(), E = end(); I != E; ++I) {
LiveInterval &li = I->second;
if (MRegisterInfo::isVirtualRegister(li.reg)) {
LiveInterval &LI = I->second;
if (MRegisterInfo::isVirtualRegister(LI.reg)) {
// If the live interval length is essentially zero, i.e. in every live
// range the use follows def immediately, it doesn't make sense to spill
// it and hope it will be easier to allocate for this li.
if (isZeroLengthInterval(&li))
li.weight = float(HUGE_VAL);
if (isZeroLengthInterval(&LI))
LI.weight = float(HUGE_VAL);
if (EnableReweight) {
// Divide the weight of the interval by its size. This encourages
// spilling of intervals that are large and have few uses, and
// discourages spilling of small intervals with many uses.
unsigned Size = 0;
for (LiveInterval::iterator II = LI.begin(), E = LI.end(); II != E;++II)
Size += II->end - II->start;
LI.weight /= Size;
}
}
}