From b75a663707e40a6b72bf404e7fbf08f7d9e1eb90 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Tue, 7 Nov 2006 07:18:40 +0000 Subject: [PATCH] Add a new llcbeta option. This speeds up viterbi from 12.34 to 8.76s on X86. If happy, I'll enable this by default. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31493 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/LiveIntervalAnalysis.cpp | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp index 118a2e0a6e2..ec2470a04a3 100644 --- a/lib/CodeGen/LiveIntervalAnalysis.cpp +++ b/lib/CodeGen/LiveIntervalAnalysis.cpp @@ -59,6 +59,9 @@ namespace { EnableJoining("join-liveintervals", cl::desc("Coallesce copies (default=true)"), cl::init(true)); + static cl::opt + 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; + } } }