If deleting a reload instruction due to reuse (value is available in register R and reload is targeting R), make sure to invalidate the kill information of the last kill.

llvm-svn: 44894

llvm-svn: 44612

llvm-svn: 44611

llvm-svn: 44609

  This allows an important optimization to be re-enabled.
- If all uses / defs of a split interval can be folded, give the interval a
  low spill weight so it would not be picked in case spilling is needed (avoid
  pushing other intervals in the same BB to be spilled).

llvm-svn: 44601

the stored register is killed.

llvm-svn: 44600

llvm-svn: 44587

Spiller unfold optimization bug: do not clobber a reusable stack slot value unless it can be modified.

llvm-svn: 44575

llvm-svn: 44549

llvm-svn: 44531

llvm-svn: 44517

llvm-svn: 44428

llvm-svn: 44386

When a live interval is being spilled, rather than creating short, non-spillable
intervals for every def / use, split the interval at BB boundaries. That is, for
every BB where the live interval is defined or used, create a new interval that
covers all the defs and uses in the BB.

This is designed to eliminate one common problem: multiple reloads of the same
value in a single basic block. Note, it does *not* decrease the number of spills
since no copies are inserted so the split intervals are *connected* through
spill and reloads (or rematerialization). The newly created intervals can be
spilled again, in that case, since it does not span multiple basic blocks, it's
spilled in the usual manner. However, it can reuse the same stack slot as the
previously split interval.

This is currently controlled by -split-intervals-at-bb.

llvm-svn: 44198

MachineOperand auxInfo. Previous clunky implementation uses an external map
to track sub-register uses. That works because register allocator uses
a new virtual register for each spilled use. With interval splitting (coming
soon), we may have multiple uses of the same register some of which are
of using different sub-registers from others. It's too fragile to constantly
update the information.

llvm-svn: 44104

llvm-svn: 43644

- Remove a bogus assertion.

llvm-svn: 43211

Turn a store folding instruction into a load folding instruction. e.g.
     xorl  %edi, %eax
     movl  %eax, -32(%ebp)
     movl  -36(%ebp), %eax
     orl   %eax, -32(%ebp)
=>
     xorl  %edi, %eax
     orl   -36(%ebp), %eax
     mov   %eax, -32(%ebp)
This enables the unfolding optimization for a subsequent instruction which will
also eliminate the newly introduced store instruction.

llvm-svn: 43192

Turn this:
movswl  %ax, %eax
movl    %eax, -36(%ebp)
xorl    %edi, -36(%ebp)
into
movswl  %ax, %eax
xorl    %edi, %eax
movl    %eax, -36(%ebp)
by unfolding the load / store xorl into an xorl and a store when we know the
value in the spill slot is available in a register. This doesn't change the
number of instructions but reduce the number of times memory is accessed.

Also unfold some load folding instructions and reuse the value when similar
situation presents itself.

llvm-svn: 42947

(almost) a register copy. However, it always coalesced to the register of the
RHS (the super-register). All uses of the result of a EXTRACT_SUBREG are sub-
register uses which adds subtle complications to load folding, spiller rewrite,
etc.

llvm-svn: 42899

Tested with "make check"!

llvm-svn: 42346

isRegister, isImmediate, and isMachineBasicBlock, which are equivalent,
and more popular.

llvm-svn: 41958

Add instruction dump output.  This helps find bugs.

llvm-svn: 41744

If the source of a move is in spill slot, the reload may be folded to essentially a load from stack slot. It's ok to mark the stack slot value as available for reuse. But it should not be clobbered since the destination of the move is live.

llvm-svn: 41109

- If the defs of a spilled rematerializable MI are dead after the spill store is deleted, delete
  the def MI as well.

llvm-svn: 41086

If a MI's def is remat as well as spilled, and the store is later deemed dead, mark the def operand as isDead.

llvm-svn: 41083

no more uses within the MBB and the spilled value isn't live out of the MBB.
Then it's safe to delete the spill store.

llvm-svn: 41069

spilled value is available for reuse.

llvm-svn: 41067

Re-implement trivial rematerialization. This allows def MIs whose live intervals that are coalesced to be rematerialized.

llvm-svn: 41060

llvm-svn: 39748

llvm-svn: 38534

llvm-svn: 38525

with a general target hook to identify rematerializable instructions. Some
instructions are only rematerializable with specific operands, such as loads
from constant pools, while others are always rematerializable. This hook
allows both to be identified as being rematerializable with the same
mechanism.

llvm-svn: 37644

implementation for x86.

llvm-svn: 37576

llvm-svn: 36483

llvm-svn: 36452

llvm-svn: 35660

register more than once.

llvm-svn: 35513

TID->numOperands.

llvm-svn: 35375

llvm-svn: 35365