tree 16a64afd13e03a5d1ff16ed1a582b60d11469215
parent a637f6c872b972eba9f53f75ccbd09a61d7f1e70
author Jakob Stoklund Olesen <stoklund@2pi.dk> 1357362009 +0000
committer Copybara-Service <copybara-worker@google.com> 1601300683 -0700

Use ArrayRecycler for MachineInstr operand lists.

Instead of an std::vector<MachineOperand>, use MachineOperand arrays
from an ArrayRecycler living in MachineFunction.

This has several advantages:

- MachineInstr now has a trivial destructor, making it possible to
  delete them in batches when destroying MachineFunction. This will be
  enabled in a later patch.

- Bypassing malloc() and free() can be faster, depending on the system
  library.

- MachineInstr objects and their operands are allocated from the same
  BumpPtrAllocator, so they will usually be next to each other in
  memory, providing better locality of reference.

- Reduce MachineInstr footprint. A std::vector is 24 bytes, the new
  operand array representation only uses 8+4+1 bytes in MachineInstr.

- Better control over operand array reallocations. In the old
  representation, the use-def chains would be reordered whenever a
  std::vector reached its capacity. The new implementation never changes
  the use-def chain order.

Note that some decisions in the code generator depend on the use-def
chain orders, so this patch may cause different assembly to be produced
in a few cases.

llvm-svn: 171598
GitOrigin-RevId: 1bfeecb491060af8fb0a69451f10cd535e2d2e1c