Don't depend on LiveIntervals::hasInterval() to determine if a physreg
is reserved and constant.

llvm-svn: 159013

Also make sure registers aren't erased twice if the dead def mentions
the register twice.

This fixes PR12911.

llvm-svn: 157254

Dead code elimination during coalescing could cause a virtual register
to be split into connected components. The following rewriting would be
confused about the already joined copies present in the code, but
without a corresponding value number in the live range.

Erase all joined copies instantly when joining intervals such that the
MI and LiveInterval representations are always in sync.

llvm-svn: 157135

The dead code elimination with callbacks is still useful.

llvm-svn: 157100

No functional change.

llvm-svn: 157079

llvm-svn: 153975

Fixes to r153903.  Added missing explanation of behaviour when the VirtRegMap is NULL.  Also changed it in this case to just avoid updating the map, but live ranges or intervals will still get updated and created

llvm-svn: 153914

llvm-svn: 153906

Refactored the LiveRangeEdit interface so that MachineFunction, TargetInstrInfo, MachineRegisterInfo, LiveIntervals, and VirtRegMap are all passed into the constructor and stored as members instead of passed in to each method.

llvm-svn: 153903

methods are no longer needed now that LinearScan has gone away.

(Contains tweaks trivialSpillEverywhere to enable the removal of getNewVRegs).

llvm-svn: 151658

llvm-svn: 150820

llvm-svn: 146960

If we create new intervals for a variable that is being spilled, then those new intervals are not guaranteed to also spill.  This means that anything reading from the original spilling value might not get the correct value if spills were missed.

Fixes <rdar://problem/10546864>

llvm-svn: 146428

generator to it. For non-bundle instructions, these behave exactly the same
as the MC layer API.

For properties like mayLoad / mayStore, look into the bundle and if any of the
bundled instructions has the property it would return true.
For properties like isPredicable, only return true if *all* of the bundled
instructions have the property.
For properties like canFoldAsLoad, isCompare, conservatively return false for
bundles.

llvm-svn: 146026

The old naming scheme (load/use/def/store) can be traced back to an old
linear scan article, but the names don't match how slots are actually
used.

The load and store slots are not needed after the deferred spill code
insertion framework was deleted.

The use and def slots don't make any sense because we are using
half-open intervals as is customary in C code, but the names suggest
closed intervals.  In reality, these slots were used to distinguish
early-clobber defs from normal defs.

The new naming scheme also has 4 slots, but the names match how the
slots are really used.  This is a purely mechanical renaming, but some
of the code makes a lot more sense now.

llvm-svn: 144503

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

Remat during spilling triggers dead code elimination. If a phi-def
becomes unused, that may also cause live ranges to split into separate
connected components.

This type of splitting is different from normal live range splitting. In
particular, there may not be a common original interval.

When the split range is its own original, make sure that the new
siblings are also their own originals. The range being split cannot be
used as an original since it doesn't cover the new siblings.

llvm-svn: 134413

llvm-svn: 130931

When an interfering live range ends at a dead slot index between two
instructions, make sure that the inserted copy instruction gets a slot index
after the dead ones. This makes it possible to avoid the interference.

Ideally, there shouldn't be interference ending at a deleted instruction, but
physical register coalescing can sometimes do that to sub-registers.

This fixes PR9823.

llvm-svn: 130687

llvm-svn: 129883

llvm-svn: 129579

In particular, don't repeatedly recompute the PIC base live range after rematerialization.

llvm-svn: 129275

When dead code elimination removes all but one use, try to fold the single def into the remaining use.

Rematerialization can leave single-use loads behind that we might as well fold whenever possible.

llvm-svn: 128918

When DCE clones a live range because it separates into connected components,
make sure that the clones enter the same register allocator stage as the
register they were cloned from.

For instance, clones may be split even when they where created during spilling.
Other registers created during spilling are not candidates for splitting or even
(re-)spilling.

llvm-svn: 128524

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

llvm-svn: 128490

llvm-svn: 128469

The instruction to be rematerialized may not be the one defining the register
that is being spilled. The traceSiblingValue() function sees through sibling
copies to find the remat candidate.

llvm-svn: 128449

The register allocator needs to know when the range shrinks.

llvm-svn: 128145

I have convinced myself that it can only happen when a phi value dies. When it
happens, allocate new virtual registers for the components.

llvm-svn: 127827

The register allocator needs to adjust its live interval unions when that happens.

llvm-svn: 127774

llvm-svn: 127773

llvm-svn: 127771

This allows the allocator to free any resources used by the virtual register,
including physical register assignments.

llvm-svn: 127560

This will we used for keeping register allocator data structures up to date
while LiveRangeEdit is trimming live intervals.

llvm-svn: 127300

LiveRangeEdit::eliminateDeadDefs() will eventually be used by coalescing,
splitting, and spilling for dead code elimination. It can delete chains of dead
instructions as long as there are no dependency loops.

llvm-svn: 127287

llvm-svn: 127181

llvm-svn: 126002

All new virtual registers created for spilling or splitting point back to their original.

llvm-svn: 125980

llvm-svn: 118661

give them individual stack slots once the are actually spilled.

llvm-svn: 117945