Commit Graph

4 Commits

Author SHA1 Message Date
Bill Wendling
d8ab9b415d - Fix description of SUBREG_TO_REG. It's not going to generate a zext. But it
is used to assert that an *implicit* zext is performed.

- Fix grammar-o in INSERT_SUBREG. (required reformatting)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105735 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-09 18:15:36 +00:00
Evan Cheng
b55c8bed9d Add a pseudo instruction REG_SEQUENCE that takes a list of registers and
sub-register indices and outputs a single super register which is formed from
a consecutive sequence of registers.

This is used as register allocation / coalescing aid and it is useful to
represent instructions that output register pairs / quads. For example,
v1024, v1025 = vload <address>
where v1024 and v1025 forms a register pair.

This really should be modelled as
v1024<3>, v1025<4> = vload <address>
but it would violate SSA property before register allocation is done.

Currently we use insert_subreg to form the super register:
v1026 = implicit_def
v1027 - insert_subreg v1026, v1024, 3
v1028 = insert_subreg v1027, v1025, 4
...
      = use v1024
      = use v1028

But this adds pseudo live interval overlap between v1024 and v1025.

We can now modeled it as
v1024, v1025 = vload <address>
v1026 = REG_SEQUENCE v1024, 3, v1025, 4
...
      = use v1024
      = use v1026

After coalescing, it will be
v1026<3>, v1025<4> = vload <address>
...
      = use v1026<3>
      = use v1026


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102815 91177308-0d34-0410-b5e6-96231b3b80d8
2010-05-01 00:28:44 +00:00
Dan Gohman
2516d0d7b1 Use Doxygen comment syntax.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97451 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-01 17:45:15 +00:00
Chris Lattner
518bb53485 move target-independent opcodes out of TargetInstrInfo
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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95687 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-09 19:54:29 +00:00