diff options
| author | Manman Ren <mren@apple.com> | 2012-06-15 21:32:12 +0000 |
|---|---|---|
| committer | Manman Ren <mren@apple.com> | 2012-06-15 21:32:12 +0000 |
| commit | 307473dec0e2fa966037d04725a40b33669dddc8 (patch) | |
| tree | bf59f915327ca87811406874fc88a9a46b692f9e /lib/Target | |
| parent | 695fd1a4555aae6cef9292d0d39967a949ea8782 (diff) | |
ARM: optimization for sub+abs.
This patch will optimize abs(x-y)
FROM
sub, movs, rsbmi
TO
subs, rsbmi
For abs, we will use cmp instead of movs. This is necessary because we already
have an existing peephole pass which optimizes away cmp following sub.
rdar: 11633193
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158551 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target')
| -rw-r--r-- | lib/Target/ARM/ARMISelLowering.cpp | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp index c48fa763b4..bf17f15caf 100644 --- a/lib/Target/ARM/ARMISelLowering.cpp +++ b/lib/Target/ARM/ARMISelLowering.cpp @@ -6808,9 +6808,6 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI, MachineRegisterInfo &MRI = Fn->getRegInfo(); // In Thumb mode S must not be specified if source register is the SP or // PC and if destination register is the SP, so restrict register class - unsigned NewMovDstReg = MRI.createVirtualRegister(isThumb2 ? - (const TargetRegisterClass*)&ARM::rGPRRegClass : - (const TargetRegisterClass*)&ARM::GPRRegClass); unsigned NewRsbDstReg = MRI.createVirtualRegister(isThumb2 ? (const TargetRegisterClass*)&ARM::rGPRRegClass : (const TargetRegisterClass*)&ARM::GPRRegClass); @@ -6827,12 +6824,10 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI, // fall through to SinkMBB RSBBB->addSuccessor(SinkBB); - // insert a movs at the end of BB - BuildMI(BB, dl, TII->get(isThumb2 ? ARM::t2MOVr : ARM::MOVr), - NewMovDstReg) - .addReg(ABSSrcReg, RegState::Kill) - .addImm((unsigned)ARMCC::AL).addReg(0) - .addReg(ARM::CPSR, RegState::Define); + // insert a cmp at the end of BB + AddDefaultPred(BuildMI(BB, dl, + TII->get(isThumb2 ? ARM::t2CMPri : ARM::CMPri)) + .addReg(ABSSrcReg).addImm(0)); // insert a bcc with opposite CC to ARMCC::MI at the end of BB BuildMI(BB, dl, @@ -6844,7 +6839,7 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI, // by if-conversion pass BuildMI(*RSBBB, RSBBB->begin(), dl, TII->get(isThumb2 ? ARM::t2RSBri : ARM::RSBri), NewRsbDstReg) - .addReg(NewMovDstReg, RegState::Kill) + .addReg(ABSSrcReg, RegState::Kill) .addImm(0).addImm((unsigned)ARMCC::AL).addReg(0).addReg(0); // insert PHI in SinkBB, @@ -6852,7 +6847,7 @@ ARMTargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI, BuildMI(*SinkBB, SinkBB->begin(), dl, TII->get(ARM::PHI), ABSDstReg) .addReg(NewRsbDstReg).addMBB(RSBBB) - .addReg(NewMovDstReg).addMBB(BB); + .addReg(ABSSrcReg).addMBB(BB); // remove ABS instruction MI->eraseFromParent(); |