When findReachingDefs() finds that only one value can reach the basic
block, just copy the work list of visited blocks directly into the live
interval.

Sort the block list and use a LiveRangeUpdater to make the bulk add
fast.

When multiple reaching defs are found, transfer the work list to the
updateSSA() work list as before. Also use LiveRangeUpdater in
updateLiveIns() following updateSSA().

This makes live interval analysis more than 3x faster on one huge test
case.

llvm-svn: 175685

Kill flags are difficult to maintain, and liveness queries are better
handled by live intervals.

Kill flags are reinserted after register allocation by addKillFlags().

llvm-svn: 163334

A value number is a PHI def if and only if it begins at a block
boundary. This can be derived from the def slot, a separate flag is not
necessary.

llvm-svn: 160893

Catch uses of undefined physregs that haven't been added to basic block
live-in lists. Run the verifier to pinpoint the problem.

Also run the verifier when a virtual register use is not jointly
dominated by defs.

llvm-svn: 160207

These LiveRangeCalc methods are to be used when computing a live range
from scratch.

llvm-svn: 158027

Remove the same pointers from all the other LiveRangeCalc functions,
simplifying the interface.

llvm-svn: 157941

If a value is defined by a COPY, that instuction can easily and cheaply
be found by getInstructionFromIndex(VNI->def).

This reduces the size of VNInfo from 24 to 16 bytes, and improves
llc compile time by 3%.

llvm-svn: 149763

llvm-svn: 146987

Three out of four clients prefer this interface which is consistent with
extendIntervalEndTo() and LiveRangeCalc::extend().

llvm-svn: 139604

llvm-svn: 139581

SplitKit will soon need two copies of these data structures, and the
algorithms will also be useful when LiveIntervalAnalysis becomes
independent of LiveVariables.

llvm-svn: 139572