actually *removes* one of the operands, instead of just assigning both operands
the same register. This make reasoning about instructions unnecessarily complex,
because you need to know if you are before or after register allocation to match
up operand #'s with the target description file.
Changing this also gets rid of a bunch of hacky code in various places.
This patch also includes changes to fold loads into cmp/test instructions in
the X86 backend, along with a significant simplification to the X86 spill
folding code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30108 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19245 91177308-0d34-0410-b5e6-96231b3b80d8
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/.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16137 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11340 91177308-0d34-0410-b5e6-96231b3b80d8
Move Passes.h (which defines the interface to this file) to the top.
Move statistics to the top of the file.
Add a comment
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11034 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10755 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10682 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10512 91177308-0d34-0410-b5e6-96231b3b80d8
