Implicitly defined virtual registers can simply have the <undef> bit set
on all uses, and copies can be turned into implicit defs recursively.

Physical registers are a bit trickier. We handle the common case where a
physreg def is used by a nearby instruction in the same basic block. For
more complicated cases, just leave the IMPLICIT_DEF instruction in.

llvm-svn: 159149

The ProcessImplicitDefs class can be local to its implementation file.

llvm-svn: 159041

No functional change intended.

Sorry for the churn. The iterator classes are supposed to help avoid
giant commits like this one in the future. The TableGen-produced
register lists are getting quite large, and it may be necessary to
change the table representation.

This makes it possible to do so without changing all clients (again).

llvm-svn: 157854

llvm-svn: 152016

Creates a configurable regalloc pipeline.

Ensure specific llc options do what they say and nothing more: -reglloc=... has no effect other than selecting the allocator pass itself. This patch introduces a new umbrella flag, "-optimize-regalloc", to enable/disable the optimizing regalloc "superpass". This allows for example testing coalscing and scheduling under -O0 or vice-versa.

When a CodeGen pass requires the MachineFunction to have a particular property, we need to explicitly define that property so it can be directly queried rather than naming a specific Pass. For example, to check for SSA, use MRI->isSSA, not addRequired<PHIElimination>.

CodeGen transformation passes are never "required" as an analysis

ProcessImplicitDefs does not require LiveVariables.

We have a plan to massively simplify some of the early passes within the regalloc superpass.

llvm-svn: 150226

This boils down to using MachineOperand::readsReg() more.

This fixes PR11829 where a use ended up after the first def when
lowering REG_SEQUENCE instructions involving IMPLICIT_DEFs.

llvm-svn: 148996

Code like that would only be produced by bugpoint, but we should still
handle it correctly.

When a register is defined by a REG_SEQUENCE of undefs, the register
itself is undef. Previously, we would create a register with uses but no
defs.

Fixes part of PR10520.

llvm-svn: 136401

Use the opportunity to get rid of the trailing underscore variable names.

llvm-svn: 127618

llvm-svn: 122628

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: 109045

TII::isMoveInstr is going tobe completely removed.

llvm-svn: 108507

Teach ProcessImplicitDefs to transform more COPY instructions into IMPLICIT_DEF (and subsequently eliminate them). This allows machine LICM to hoist IMPLICIT_DEF's. PR7620.

llvm-svn: 108304

EXTRACT_SUBREG no longer appears as a machine instruction. Use COPY instead.

Add isCopy() checks in many places using isMoveInstr() and isExtractSubreg().
The isMoveInstr hook will be removed later.

llvm-svn: 107879

Fix X86InstrInfo::convertToThreeAddressWithLEA to generate COPY instead of
INSERT_SUBREG.

llvm-svn: 107878

Buildbot breakage.

llvm-svn: 107744

llvm-svn: 107732

INSERT_SUBREG will now only appear in SSA machine instructions.

Fix the handling of partial redefs in ProcessImplicitDefs. This is now relevant
since partial redef COPY instructions appear.

llvm-svn: 107726

This code is transitional, it will soon be possible to eliminate
isExtractSubreg, isInsertSubreg, and isMoveInstr in most places.

llvm-svn: 107547

llvm-svn: 103450

llvm-svn: 103436

A virtual register can be used before it is defined in the same MBB if the MBB
is part of a loop. Teach the implicit-def pass about this case.

llvm-svn: 96279

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

ProcessImplicitDefs would only mark one operand per instruction with <undef>.
This fixed PR6086.

llvm-svn: 95319

llvm-svn: 92567

llvm-svn: 89905

ProcessImplicitDefs should watch out for invalidated iterator and extra implicit operands on copies.

llvm-svn: 89880

llvm-svn: 88895

Make sure when ProcessImplicitDefs removes a copy which kills its source reg that it
removes the copy from said reg's Kills list.

llvm-svn: 88881

This introduces a new pass, SlotIndexes, which is responsible for numbering
instructions for register allocation (and other clients). SlotIndexes numbering
is designed to match the existing scheme, so this patch should not cause any
changes in the generated code.

For consistency, and to avoid naming confusion, LiveIndex has been renamed
SlotIndex.

The processImplicitDefs method of the LiveIntervals analysis has been moved
into its own pass so that it can be run prior to SlotIndexes. This was
necessary to match the existing numbering scheme.

llvm-svn: 85979