when we fail to place all the blocks of a loop. Currently this is
happening for unnatural loops, and this logic helps more immediately
point to the problem.

llvm-svn: 144504

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

branches that also may involve fallthrough. In the case of blocks with
no fallthrough, we can still re-order the blocks profitably. For example
instruction decoding will in some cases continue past an indirect jump,
making laying out its most likely successor there profitable.

Note, no test case. I don't know how to write a test case that exercises
this logic, but it matches the described desired semantics in
discussions with Jakob and others. If anyone has a nice example of IR
that will trigger this, that would be lovely.

Also note, there are still assertion failures in real world code with
this. I'm digging into those next, now that I know this isn't the cause.

llvm-svn: 144499

llvm-svn: 144498

llvm-svn: 144497

llvm-svn: 144496

second algorithm, but only loosely. It is more heavily based on the last
discussion I had with Andy. It continues to walk from the inner-most
loop outward, but there is a key difference. With this algorithm we
ensure that as we visit each loop, the entire loop is merged into
a single chain. At the end, the entire function is treated as a "loop",
and merged into a single chain. This chain forms the desired sequence of
blocks within the function. Switching to a single algorithm removes my
biggest problem with the previous approaches -- they had different
behavior depending on which system triggered the layout. Now there is
exactly one algorithm and one basis for the decision making.

The other key difference is how the chain is formed. This is based
heavily on the idea Andy mentioned of keeping a worklist of blocks that
are viable layout successors based on the CFG. Having this set allows us
to consistently select the best layout successor for each block. It is
expensive though.

The code here remains very rough. There is a lot that needs to be done
to clean up the code, and to make the runtime cost of this pass much
lower. Very much WIP, but this was a giant chunk of code and I'd rather
folks see it sooner than later. Everything remains behind a flag of
course.

I've added a couple of tests to exercise the issues that this iteration
was motivated by: loop structure preservation. I've also fixed one test
that was exhibiting the broken behavior of the previous version.

llvm-svn: 144495

llvm-svn: 144487

This thing is looking a lot like a virtual register map now.

llvm-svn: 144486

Nobody cared, StackSlotColoring scans the instructions to find used stack
slots.

llvm-svn: 144485

Most of this stuff was supporting the old deferred spill code insertion
mechanism.  Modern spillers just edit machine code in place.

llvm-svn: 144484

The information was only used by the register allocator in
StackSlotColoring.

llvm-svn: 144482

It was off by default.

The new register allocators don't have the problems that made it
necessary to reallocate registers during stack slot coloring.

llvm-svn: 144481

And there was much rejoicing.

llvm-svn: 144480

The very complicated VirtRegRewriter is going away.

llvm-svn: 144479

This is dead code, all register allocators use InlineSpiller.

llvm-svn: 144478

The current register allocators all use the inline spiller.

llvm-svn: 144477

It is worth noting that the old spiller would split live ranges around
basic blocks. The new spiller doesn't do that.

PBQP should do its own live range splitting with
SplitEditor::splitSingleBlock() if desired.  See
RAGreedy::tryBlockSplit().

llvm-svn: 144476

RegAllocGreedy has been the default for six months now.

Deleting RegAllocLinearScan makes it possible to also delete
VirtRegRewriter and clean up the spiller code.

llvm-svn: 144475

instance and a concrete inlined instance are the use of DW_TAG_subprogram
instead of DW_TAG_inlined_subroutine and the who owns the tree.

We were also omitting DW_AT_inline from the abstract roots. To fix this,
make sure we mark abstract instance roots with DW_AT_inline even when
we have only out-of-line instances referring to them with DW_AT_abstract_origin.

FileCheck is not a very good tool for tests like this, maybe we should add
a -verify mode to llvm-dwarfdump.

llvm-svn: 144441

llvm-svn: 144438

Some cleanup and bulletproofing for node replacement in LegalizeDAG.  To maintain LegalizeDAG invariants, whenever we a node is replaced, we must attempt to delete it, and if it still
has uses after it is replaced (which can happen in rare cases due to CSE), we must revisit it.

llvm-svn: 144432

Add a custom safepoint method, in order for language implementers to decide which machine instruction gets to be a safepoint.

llvm-svn: 144399

llvm-svn: 144360

addr DIE when adding to the dwarf accelerator tables.

llvm-svn: 144354

it first.

This is a more general fix to pr11300.

llvm-svn: 144324

as well.

llvm-svn: 144319

forward decls and have names into the dwarf accelerator types table.

llvm-svn: 144306

multiple dies per function and support C++ basenames.

llvm-svn: 144304

instruction lower optimization" in the pre-RA scheduler.

The optimization, rather the hack, was done before MI use-list was available.
Now we should be able to implement it in a better way, perhaps in the
two-address pass until a MI scheduler is available.

Now that the scheduler has to backtrack to handle call sequences. Adding
artificial scheduling constraints is just not safe. Furthermore, the hack
is not taking all the other scheduling decisions into consideration so it's just
as likely to pessimize code. So I view disabling this optimization goodness
regardless of PR11314.

llvm-svn: 144267

The TII.foldMemoryOperand hook preserves implicit operands from the
original instruction.  This is not what we want when those implicit
operands refer to the register being spilled.

Implicit operands referring to other registers are preserved.

This fixes PR11347.

llvm-svn: 144247

llvm-svn: 144216

llvm-svn: 144194

dragonegg self-host buildbot will recover (it is complaining about object
files differing between different build stages).  Original commit message:

Add a hack to the scheduler to disable pseudo-two-address dependencies in
basic blocks containing calls. This works around a problem in which
these artificial dependencies can get tied up in calling seqeunce
scheduling in a way that makes the graph unschedulable with the current
approach of using artificial physical register dependencies for calling
sequences. This fixes PR11314.

llvm-svn: 144188

llvm-svn: 144184

llvm-svn: 144172

llvm-svn: 144169

During the initial RPO traversal of the basic blocks, remember the ones
that are incomplete because of back-edges from predecessors that haven't
been visited yet.

After the initial RPO, revisit all those loop headers so the incoming
DomainValues on the back-edges can be properly collapsed.

This will properly fix execution domains on software pipelined code,
like the included test case.

llvm-svn: 144151

When merging two uncollapsed DomainValues, place a link to the active
DomainValue from the passive DomainValue.  This allows old stale
references to the passive DomainValue to be updated to point to the
active DomainValue.

The new resolve() function finds the active DomainValue and updates the
pointer.

This change makes old live-out lists more useful since they may contain
uncollapsed DomainValues that have since been merged into other
DomainValues.

llvm-svn: 144149

This allows clear() to be called on a DomainValue with references.

llvm-svn: 144147