llvm-svn: 157142

llvm-svn: 157137

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

Dead code and joined copies are now eliminated on the fly, and there is
no need for a post pass.

This makes the coalescer work like other modern register allocator
passes: Code is changed on the fly, there is no pending list of changes
to be committed.

llvm-svn: 157132

The late dead code elimination is no longer necessary.

The test changes are cause by a register hint that can be either %rdi or
%rax. The choice depends on the use list order, which this patch changes.

llvm-svn: 157131

Before rewriting uses of one value in A to register B, check that there
are no tied uses. That would require multiple A values to be rewritten.

This bug can't bite in the current version of the code for a fairly
subtle reason: A tied use would have caused 2-addr to insert a copy
before the use. If the copy has been coalesced, it will be found by the
same loop changed by this patch, and the optimization is aborted.

This was exposed by 400.perlbench and lua after applying a patch that
deletes joined copies aggressively.

llvm-svn: 157130

There is no reason to defer the collection of virtual registers whose
register class may be replaced with a larger class.

llvm-svn: 157125

This will remove the original def once it has no more uses.

llvm-svn: 157104

Remaining virtreg->physreg copies were rematerialized during
updateRegDefsUses(), but we already do the same thing in joinCopy() when
visiting the physreg copy instruction.

Eliminate the preserveSrcInt argument to reMaterializeTrivialDef(). It
is now always true.

llvm-svn: 157103

There is no need for these instructions to stick around since they are
known to be not dead.

llvm-svn: 157102

Dead copies cause problems because they are trivial to coalesce, but
removing them gived the live range a dangling end point. This patch
enables full dead code elimination which trims live ranges to their uses
so end points don't dangle.

DCE may erase multiple instructions. Put the pointers in an ErasedInstrs
set so we never risk visiting erased instructions in the work list.

There isn't supposed to be any dead copies entering RegisterCoalescer,
but they do slip by as evidenced by test/CodeGen/X86/coalescer-dce.ll.

llvm-svn: 157101

The dead code elimination with callbacks is still useful.

llvm-svn: 157100

No functional change.

llvm-svn: 157079

This will make it possible to filter out erased instructions later.

llvm-svn: 157073

Use a dedicated MachO load command to annotate data-in-code regions.
This is the same format the linker produces for final executable images,
allowing consistency of representation and use of introspection tools
for both object and executable files.

Data-in-code regions are annotated via ".data_region"/".end_data_region"
directive pairs, with an optional region type.

data_region_directive := ".data_region" { region_type }
region_type := "jt8" | "jt16" | "jt32" | "jta32"
end_data_region_directive := ".end_data_region"

The previous handling of ARM-style "$d.*" labels was broken and has
been removed. Specifically, it didn't handle ARM vs. Thumb mode when
marking the end of the section.

rdar://11459456

llvm-svn: 157062

llvm-svn: 157060

It is no longer necessary to separate VirtCopies, PhysCopies, and
ImpDefCopies. Implicitly defined copies are extremely rare after we
added the ProcessImplicitDefs pass, and physical register copies are not
joined any longer.

llvm-svn: 157059

This has been disabled for a while, and it is not a feature we want to
support. Copies between physical and virtual registers are eliminated by
good hinting support in the register allocator. Joining virtual and
physical registers is really a form of register allocation, and the
coalescer is not properly equipped to do that. In particular, it cannot
backtrack coalescing decisions, and sometimes that would cause it to
create programs that were impossible to register allocate, by exhausting
a small register class.

It was also very difficult to keep track of the live ranges of aliasing
registers when extending the live range of a physreg. By disabling
physreg joining, we can let fixed physreg live ranges remain constant
throughout the register allocator super-pass.

One type of physreg joining remains: A virtual register that has a
single value which is a copy of a reserved register can be merged into
the reserved physreg. This always lowers register pressure, and since we
don't compute live ranges for reserved registers, there are no problems
with aliases.

llvm-svn: 157055

SelectionDAGBuilder::Clusterify : main functinality was replaced with CRSBuilder::optimize, so big part of Clusterify's code was reduced.

llvm-svn: 157046

non-profitable commute using outdated info. The test case would still fail
because of poor pre-RA schedule. That will be fixed by MI scheduler.

rdar://11472010

llvm-svn: 157038

llvm-svn: 157020

llvm-svn: 157007

Introduce the basic strategy for register pressure scheduling.

1) Respect target limits at all times.

2) Indentify critical register classes (pressure sets).
   Track pressure within the scheduled region.
   Avoid increasing scheduled pressure for critical registers.

3) Avoid exceeding the max pressure of the region prior to scheduling.

Added logic for picking between the top and bottom ready Q's based on
regpressure heuristics.

Status: functional but needs to be asjusted to achieve good results.
llvm-svn: 157006

llvm-svn: 157005

llvm-svn: 157004

llvm-svn: 157003

llvm-svn: 157002

RegisterCoalescer set <undef> flags on all operands of copy instructions
that are scheduled to be removed. This is so they won't affect
shrinkToUses() by introducing false register reads.

Make sure those <undef> flags are never cleared, or shrinkToUses() could
cause live intervals to end at instructions about to be deleted.

This would be a lot simpler if RegisterCoalescer could just erase joined
copies immediately instead of keeping all the to-be-deleted instructions
around.

This fixes PR12862. Unfortunately, bugpoint can't create a sane test
case for this. Like many other coalescer problems, this failure depends
of a very fragile series of events.

<rdar://problem/11474428>

llvm-svn: 157001

Make sure useless (def-only) intervals also get verified.

llvm-svn: 157000

bugpoint-ing, it may turn into something else.

llvm-svn: 156998

SelectionDAGBuilder: CaseBlock, CaseRanges and CaseCmp changed representation of Low and High from signed to unsigned. Since unsigned ints usually simpler, faster and allows to reduce some extra signed bit checks needed before <,>,<=,>= comparisons.

llvm-svn: 156985

When widening an existing <def,reads-undef> operand to a super-register,
it may be necessary to clear the <undef> flag because the wider register
is now read-modify-write through the instruction.

Conversely, it may be necessary to add an <undef> flag when the
coalescer turns a full-register def into a sub-register def, but the
larger register wasn't live before the instruction.

This happens in test/CodeGen/ARM/coalesce-subregs.ll, but the test
is too small for the <undef> flags to affect the generated code.

llvm-svn: 156951

llvm-svn: 156909

It is now possible to coalesce weird skewed sub-register copies by
picking a super-register class larger than both original registers. The
included test case produces code like this:

  vld2.32 {d16, d17, d18, d19}, [r0]!
  vst2.32 {d18, d19, d20, d21}, [r0]

We still perform interference checking as if it were a normal full copy
join, so this is still quite conservative. In particular, the f1 and f2
functions in the included test case still have remaining copies because
of false interference.

llvm-svn: 156878

It is possible to coalesce two overlapping registers to a common
super-register that it larger than both of the original registers.

The important difference is that it may be necessary to rewrite DstReg
operands as well as SrcReg operands because the sub-register index has
changed.

This behavior is still disabled by CoalescerPair.

llvm-svn: 156869

This can happen when widening a virtual register to a super-register
class.

llvm-svn: 156867

There is no need to look at an always null SrcIdx.

llvm-svn: 156866

Now both SrcReg and DstReg can be sub-registers of the final coalesced
register.

CoalescerPair::setRegisters still rejects such copies because
RegisterCoalescer doesn't yet handle them.

llvm-svn: 156848

This feature avoids creating edges in the scheduler's dependence graph
for non-aliasing memory operations according to whichever alias
analysis is available. It has been fully tested in Hexagon. Before
making this default, it needs to be extended to handle multiple
MachineMemOperands, compile time needs more evaluation, and
benchmarking on X86 and ARM is needed.

Patch by Sergei Larin!

llvm-svn: 156842

Add the MCRegisterInfo to the factories and constructors.

Patch by Tom Stellard <Tom.Stellard@amd.com>.

llvm-svn: 156828