When a live range is contained a single block, we can split it around
instruction clusters. The current approach is very primitive, splitting before
and after the largest gap between uses.

llvm-svn: 111043

llvm-svn: 111019

numbers match. The old check could accidentally leave holes in openli.

Also let useIntv add all ranges for the phi-def value inserted by
enterIntvAtEnd. This works as long at the value mapping is established in
enterIntvAtEnd.

llvm-svn: 110995

function to do it.

llvm-svn: 110994

This can happen if the original interval has been broken into two disconnected
parts. Ideally, we should be able to detect when the graph is disconnected and
create separate intervals, but that code is not implemented yet.

Example:

Two basic blocks are both branching to a loop header. Our interval is defined in
both basic blocks, and live into the loop along both edges.

We decide to split the interval around the loop. The interval is split into an
inside part and an outside part. The outside part now has two disconnected
segments, one in each basic block.

If we later decide to split the outside interval into single blocks, we get one
interval per basic block and an empty dupli for the remainder.

llvm-svn: 110976

split intervals. THis means the analysis can be used for multiple splits as long
as curli doesn't shrink.

llvm-svn: 110975

If a phi-def value were removed from the interval, the phi-kill flags are no
longer valid.

llvm-svn: 110949

llvm-svn: 110944

llvm-svn: 110940

Before spilling a live range, we split it into a separate range for each basic
block where it is used. That way we only get one reload per basic block if the
new smaller ranges can allocate to a register.

This type of splitting is already present in the standard spiller.

llvm-svn: 110934

llvm-svn: 110826

a register before checking if it was defined.

llvm-svn: 110733

operands. We don't currently have a hook to provide "the largest super class of
A where all registers' getSubReg(subidx) is valid and in B".

llvm-svn: 110730

llvm-svn: 110726

The live interval may be used for a spill slot as well, and that spill slot
could be shared by split registers. We cannot shrink it, even if we know the
current register won't need the spill slot in that range.

llvm-svn: 110721

llvm-svn: 110720

ARM testers.

llvm-svn: 110718

llvm-svn: 110712

When splitting a live range, the new registers have fewer uses and the
permissible register class may be less constrained. Recompute the register class
constraint from the uses of new registers created for a split. This may let them
be allocated from a larger set, possibly avoiding a spill.

llvm-svn: 110703

during live range splitting.

llvm-svn: 110686

llvm-svn: 110656

llvm-svn: 110654

llvm-svn: 110653

llvm-svn: 110652

llvm-svn: 110649

Refactor and simplify code to avoid redundant checks.

llvm-svn: 110642

register at a time. This turns out to be slightly faster than iterating over
instructions, but more importantly, it allows us to compute spill weights for
new registers created after the spill weight pass has run.

Also compute the allocation hint at the same time as the spill weight. This
allows us to use the spill weight as a cost metric for copies, and choose the
most profitable hint if there is more than one possibility.

The new hints provide a very small (< 0.1%) but universal code size improvement.

llvm-svn: 110631

pass. This pass should expand with all of the small, fine-grained optimization
passes to reduce compile time and increase happiment.

llvm-svn: 110627

llvm-svn: 110623

llvm-svn: 110621

llvm-svn: 110607

llvm-svn: 110600

llvm-svn: 110590

If we are emitting COPY instructions for the REG_SEQUENCE, make sure the kill
flag goes on the last COPY. Otherwise we may be using a killed register.

<rdar://problem/8287792>

llvm-svn: 110589

llvm-svn: 110586

relatively expensive comparison analyzer on each instruction. Also rename the
comparison analyzer method to something more in line with what it actually does.

This pass is will eventually be folded into the Machine CSE pass.

llvm-svn: 110539

out of PassManager.cpp and into Core.cpp with the rest of the C binding code.

llvm-svn: 110494

necessary.

Sometimes, live range splitting doesn't shrink the current interval, but simply
changes some instructions to use a new interval. That makes the original more
suitable for spilling. In this case, we don't need to duplicate the original.

llvm-svn: 110481

llvm-svn: 110466

llvm-svn: 110464