Turn a 2-address instruction into a 3-address one when it's profitable even if the two-address operand is killed.
e.g.
%reg1024<def> = MOV r1
%reg1025<def> = ADD %reg1024, %reg1026
r0            = MOV %reg1025

If it's not possible / profitable to commute ADD, then turning ADD into a LEA saves a copy.

llvm-svn: 68065

Model inline asm constraint which ties an input to an output register as machine operand TIED_TO constraint. This eliminated the need to pre-allocate registers for these. This also allows register allocator can eliminate the unneeded copies.

llvm-svn: 67512

llvm-svn: 67335

Look for situations like this:                                                                                                                                                              
%reg1024<def> = MOV r1                                                                                                                                                                      
%reg1025<def> = MOV r0                                                                                                                                                                      
%reg1026<def> = ADD %reg1024, %reg1025                                                                                                                                                      
r0            = MOV %reg1026                                                                                                                                                                
Commute the ADD to hopefully eliminate an otherwise unavoidable copy.

llvm-svn: 65752

If two-address def is dead and the instruction does not define other registers, and it doesn't produce side effects, just delete the instruction.

llvm-svn: 65218

llvm-svn: 63198

Teach 2addr pass to be do more commuting. If both uses of a two-address instruction are killed, but the first operand has a use before and after the def, commute if the second operand does not suffer from the same issue.
%reg1028<def> = EXTRACT_SUBREG %reg1027<kill>, 1                                                                                                                                     
%reg1029<def> = MOV8rr %reg1028                                                                                                                                                      
%reg1029<def> = SHR8ri %reg1029, 7, %EFLAGS<imp-def,dead>                                                                                                                            
insert => %reg1030<def> = MOV8rr %reg1028                                                                                                                                            
%reg1030<def> = ADD8rr %reg1028<kill>, %reg1029<kill>, %EFLAGS<imp-def,dead>                                                                                                         

In this case, it might not be possible to coalesce the second MOV8rr                                                                                                                 
instruction if the first one is coalesced. So it would be profitable to                                                                                                              
commute it:                                                                                                                                                                          
%reg1028<def> = EXTRACT_SUBREG %reg1027<kill>, 1                                                                                                                                     
%reg1029<def> = MOV8rr %reg1028                                                                                                                                                      
%reg1029<def> = SHR8ri %reg1029, 7, %EFLAGS<imp-def,dead>                                                                                                                            
insert => %reg1030<def> = MOV8rr %reg1029                                                                                                                                            
%reg1030<def> = ADD8rr %reg1029<kill>, %reg1028<kill>, %EFLAGS<imp-def,dead>

llvm-svn: 62954

llvm-svn: 62893

llvm-svn: 61715

the debug output, so that the updated liveness flags are
reflected in the debug output.

llvm-svn: 59147

llvm-svn: 57259

isReg, etc., from isRegister, etc.

llvm-svn: 57006

llvm-svn: 55779

llvm-svn: 55434

llvm-svn: 55430

- Remove calls to copyKillDeadInfo which is an N^2 function. Instead, propagate kill / dead markers as new instructions are constructed in foldMemoryOperand, convertToThressAddress, etc.
- Also remove LiveVariables::instructionChanged, etc. Replace all calls with cheaper calls which update VarInfo kill list.

llvm-svn: 53097

- Add LiveVariables::replaceKillInstruction. This does a subset of instructionChanged. That is, it only update the VarInfo.kills if the new instruction is known to have the correct dead and kill markers.
- CommuteInstruction copies kill / dead markers over to new instruction. So use replaceKillInstruction instead.

llvm-svn: 53061

Make LiveVariables even more optional, by making it optional in the call to TargetInstrInfo::convertToThreeAddressInstruction
Also, if LV isn't around, then TwoAddr doesn't need to be updating flags, since they won't have been set in the first place.

llvm-svn: 53058

TwoAddressInstructionPass doesn't really require LiveVariables, it just needs to update it if it's already around.

llvm-svn: 53049

llvm-svn: 52920

llvm-svn: 52701

llvm-svn: 52487

llvm-svn: 52452

like.

llvm-svn: 51662

that it's safe to remat an instruction.

llvm-svn: 51659

before deleting the instruction.

llvm-svn: 51609

Running /Users/void/llvm/llvm.src/test/CodeGen/X86/dg.exp ...
FAIL: /Users/void/llvm/llvm.src/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
Failed with exit(1) at line 1
while running: llvm-as < /Users/void/llvm/llvm.src/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll | llc -march=x86 -mattr=+sse2 -stats |&  grep {1 .*folded into instructions}
child process exited abnormally

Make this conditional for now.

llvm-svn: 51563

LBB1_3:   # bb
...
        xorl    %ebp, %ebp
        subl    (%ebx), %ebp
...
        incl    %ecx
        cmpl    %edi, %ecx
        jl      LBB1_3  # bb

Whe using machine LICM, LLVM converts it into:

        xorl %esi, %esi
LBB1_3: # bb
...
        movl    %esi, %ebp
        subl    (%ebx), %ebp
...
        incl    %ecx
        cmpl    %edi, %ecx
        jl      LBB1_3  # bb

Two address conversion inserts the copy instruction. However, it's cheaper to
rematerialize it, and remat helps reduce register pressure.

llvm-svn: 51562

address of the PassInfo directly instead of calling getPassInfo.
This eliminates a bunch of dynamic initializations of static data.

Also, fold RegisterPassBase into PassInfo, make a bunch of its
data members const, and rearrange some code to initialize data
members in constructors instead of using setter member functions.

llvm-svn: 51022

several things that were neither in an anonymous namespace nor static
but not intended to be global.

llvm-svn: 51017

 - Comment fixes.
 - Moar whitespace.
 - Made ivars "private" by default.
No functionality change.

llvm-svn: 50926

llvm-svn: 48853

llvm-svn: 48337

Don't try to sink 3-address instruction if convertToThreeAddress created more than one instructions.

llvm-svn: 48336

llvm-svn: 48334

TwoAddressInstructionPass enhancement. After it converts a two address instruction into a 3-address one, sink it past the instruction that kills the read-mod-write register if its definition is used past the kill. This reduces the number of live register by one.

llvm-svn: 48333

findRegisterUseOperandIdx, findRegisterDefOperandIndx. Fix some naming inconsistencies.

llvm-svn: 47927

llvm-svn: 46930

llvm-svn: 46016

Make MachineInstr::getDesc return a reference instead
of a pointer, since it can never be null.

llvm-svn: 45695