The main advantages here are way better heuristics, taking into account not
just loop depth but also __builtin_expect and other static heuristics and will
eventually learn how to use profile info. Most of the work in this patch is
pushing the MachineBlockFrequencyInfo analysis into the right places.

This is good for a 5% speedup on zlib's deflate (x86_64), there were some very
unfortunate spilling decisions in its hottest loop in longest_match(). Other
benchmarks I tried were mostly neutral.

This changes register allocation in subtle ways, update the tests for it.
2012-02-20-MachineCPBug.ll was deleted as it's very fragile and the instruction
it looked for was gone already (but the FileCheck pattern picked up unrelated
stuff).

llvm-svn: 184105

llvm-svn: 178949

All callers can simply use the corresponding MRI functions.

llvm-svn: 165985

Based on CR feedback from r162301 and Craig Topper's refactoring in r162347
here are a few other places that could use the same API (& in one instance drop
a Function.h dependency).

llvm-svn: 162367

Add a getName function to MachineFunction. Use it in places that previously did getFunction()->getName(). Remove includes of Function.h that are no longer needed.

llvm-svn: 162347

That is a DenseMap iterator keyed by pointers, so the iteration order is
nondeterministic.

I would like to replace the DenseMap with an IndexedMap which doesn't
allow iteration.

llvm-svn: 158856

It is an old function that does a lot more than required by
CalcSpillWeights, which was the only remaining caller.

The isRematerializable() function never actually sets the isLoad
argument, so don't try to compute that.

llvm-svn: 157973

This function doesn't have anything to do with spill weights, and MRI
already has functions for manipulating the register class of a virtual
register.

llvm-svn: 137123

The constraints are represented by the register class of the original
virtual register created for the inline asm. If the register class were
included in the operand descriptor, we might be able to do this.

For now, just give up on regclass inflation when inline asm is involved.

No test case, this bug hasn't happened yet.

llvm-svn: 134226

llvm-svn: 133944

When instructions are deleted, they leave tombstone SlotIndex entries.
The isZeroLength method should ignore these null indexes.

This causes RABasic to sometimes spill a callee-saved register in the
abi-isel.ll test, so don't run that test with -regalloc=basic.  Prioritizing
register allocation according to spill weight can cause more registers to be
used.

llvm-svn: 131436

This has two effects: 1. We never inflate to a larger register class than what
the sub-target can handle. 2. Completely unconstrained virtual registers get the
largest possible register class.

llvm-svn: 130229

The spill weight is not recomputed for an unspillable register - it stays infinite.

llvm-svn: 128490

llvm-svn: 127388

Simplify the spill weight calculation a bit by bypassing
getApproximateInstructionCount() and using LiveInterval::getSize() directly.
This changes the computed spill weights, but only by a constant factor in each
function. It should not affect how spill weights compare against each other, and
so it shouldn't affect code generation.

llvm-svn: 125530

Print virtual registers numbered from 0 instead of the arbitrary
FirstVirtualRegister. The first virtual register is printed as %vreg0.
TRI::NoRegister is printed as %noreg.

llvm-svn: 123107

perform initialization without static constructors AND without explicit initialization
by the client.  For the moment, passes are required to initialize both their
(potential) dependencies and any passes they preserve.  I hope to be able to relax
the latter requirement in the future.

llvm-svn: 116334

llvm-svn: 115996

llvm-svn: 110940

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

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

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

llvm-svn: 109045

llvm-svn: 108556

llvm-svn: 107556

Moderate the weight given to very small intervals.

The spill weight given to new intervals created when spilling was not
normalized in the same way as the original spill weights calculated by
CalcSpillWeights. That meant that restored registers would tend to hang around
because they had a much higher spill weight that unspilled registers.

This improves the runtime of a few tests by up to 10%, and there are no
significant regressions.

llvm-svn: 96613

llvm-svn: 95747

llvm-svn: 95746

llvm-svn: 95745

into TargetOpcodes.h.  #include the new TargetOpcodes.h
into MachineInstr.  Add new inline accessors (like isPHI())
to MachineInstr, and start using them throughout the 
codebase.

llvm-svn: 95687

llvm-svn: 95647

Change errs() to dbgs().

llvm-svn: 92099

This fixes an in-place update bug where code inserted at the end of basic blocks may not be covered by existing intervals which were live across the entire block. It is also consistent with the way ranges are specified for live intervals.

llvm-svn: 91859

Moved spill weight calculation out of SimpleRegisterCoalescing and into its own pass: CalculateSpillWeights.

llvm-svn: 91273