1. If we are two-addressing a commutable instruction and the LHS is not the
   last use of the variable, see if the instruction is the last use of the
   RHS.  If so, commute the instruction, allowing us to avoid a
   register-register copy in many cases for common instructions like ADD, OR,
   AND, etc on X86.
2. If #1 doesn't hold, and if this is an instruction that also existing in
   3-address form, promote the instruction to a 3-address instruction to
   avoid the register-register copy.  We can do this for several common
   instructions in X86, including ADDrr, INC, DEC, etc.

This patch implements test/Regression/CodeGen/X86/commute-two-addr.ll,
overlap-add.ll, and overlap-shift.ll when I check in the X86 support for it.

llvm-svn: 19245

Move include/Config and include/Support into include/llvm/Config,
include/llvm/ADT and include/llvm/Support. From here on out, all LLVM
public header files must be under include/llvm/.

llvm-svn: 16137

llvm-svn: 15779

llvm-svn: 15107

llvm-svn: 15098

llvm-svn: 15091

llvm-svn: 15089

llvm-svn: 14997

Made a fix so that you can print out MachineInstrs that belong to a MachineBasicBlock that is not yet attached to a MachineFunction. This change includes changing the third operand (TargetMachine) to a pointer for the MachineInstr::print function.

llvm-svn: 14389

llvm-svn: 13956

llvm-svn: 11573

analysis. It should only preserve them and update LiveVariables if it
already ran.

llvm-svn: 11479

llvm-svn: 11430

llvm-svn: 11393

ilist of MachineInstr objects. This allows constant time removal and
insertion of MachineInstr instances from anywhere in each
MachineBasicBlock. It also allows for constant time splicing of
MachineInstrs into or out of MachineBasicBlocks.

llvm-svn: 11340

llvm-svn: 11129

operand of the instruction and thus simplify the register allocation.

llvm-svn: 11124

llvm-svn: 11091

llvm-svn: 11087

Fix a spello
Tighten up the assertion checking

No functionality changes.

llvm-svn: 11036

* Turn a bunch of instance variables into automatic variables

llvm-svn: 11035

Move Passes.h (which defines the interface to this file) to the top.
Move statistics to the top of the file.
Add a comment

llvm-svn: 11034

LiveVariables::HandlePhysRegDef private they use information that is
not in memory when LiveVariables finishes the analysis.

Also update the TwoAddressInstructionPass to not use this interface.

llvm-svn: 10755

llvm-svn: 10692

A = B op C where A == C, but this cannot really occur in practice
because of SSA form. Add an assert to check that just to be safe.

llvm-svn: 10682

llvm-svn: 10681

instead, since this pass doesn't expose any state to its users.

llvm-svn: 10520

more operands and the two first operands are constrained to be the
same. The pass takes an instruction of the form:

        a = b op c

and transforms it into:

        a = b
        a = a op c

and also preserves live variables.

llvm-svn: 10512