diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/ARM/ARMConstantIslandPass.cpp | 64 | ||||
| -rw-r--r-- | lib/Target/ARM/ARMInstrThumb.td | 9 |
2 files changed, 62 insertions, 11 deletions
diff --git a/lib/Target/ARM/ARMConstantIslandPass.cpp b/lib/Target/ARM/ARMConstantIslandPass.cpp index 0a27d179e9..981962522d 100644 --- a/lib/Target/ARM/ARMConstantIslandPass.cpp +++ b/lib/Target/ARM/ARMConstantIslandPass.cpp @@ -41,6 +41,7 @@ STATISTIC(NumUBrFixed, "Number of uncond branches fixed"); STATISTIC(NumTBs, "Number of table branches generated"); STATISTIC(NumT2CPShrunk, "Number of Thumb2 constantpool instructions shrunk"); STATISTIC(NumT2BrShrunk, "Number of Thumb2 immediate branches shrunk"); +STATISTIC(NumCBZ, "Number of CBZ / CBNZ formed"); namespace { /// ARMConstantIslands - Due to limited PC-relative displacements, ARM @@ -1486,24 +1487,65 @@ bool ARMConstantIslands::OptimizeThumb2Branches(MachineFunction &MF) { Bits = 11; Scale = 2; break; - case ARM::t2Bcc: + case ARM::t2Bcc: { NewOpc = ARM::tBcc; Bits = 8; - Scale = 2; + Scale = 2; break; } - if (!NewOpc) + } + if (NewOpc) { + unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale; + MachineBasicBlock *DestBB = Br.MI->getOperand(0).getMBB(); + if (BBIsInRange(Br.MI, DestBB, MaxOffs)) { + Br.MI->setDesc(TII->get(NewOpc)); + MachineBasicBlock *MBB = Br.MI->getParent(); + BBSizes[MBB->getNumber()] -= 2; + AdjustBBOffsetsAfter(MBB, -2); + ++NumT2BrShrunk; + MadeChange = true; + } + } + + Opcode = Br.MI->getOpcode(); + if (Opcode != ARM::tBcc) continue; - unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale; + NewOpc = 0; + unsigned PredReg = 0; + ARMCC::CondCodes Pred = llvm::getInstrPredicate(Br.MI, PredReg); + if (Pred == ARMCC::EQ) + NewOpc = ARM::tCBZ; + else if (Pred == ARMCC::NE) + NewOpc = ARM::tCBNZ; + if (!NewOpc) + continue; MachineBasicBlock *DestBB = Br.MI->getOperand(0).getMBB(); - if (BBIsInRange(Br.MI, DestBB, MaxOffs)) { - Br.MI->setDesc(TII->get(NewOpc)); - MachineBasicBlock *MBB = Br.MI->getParent(); - BBSizes[MBB->getNumber()] -= 2; - AdjustBBOffsetsAfter(MBB, -2); - ++NumT2BrShrunk; - MadeChange = true; + // Check if the distance is within 126. Subtract starting offset by 2 + // because the cmp will be eliminated. + unsigned BrOffset = GetOffsetOf(Br.MI) + 4 - 2; + unsigned DestOffset = BBOffsets[DestBB->getNumber()]; + if (BrOffset < DestOffset && (DestOffset - BrOffset) <= 126) { + MachineBasicBlock::iterator CmpMI = Br.MI; --CmpMI; + if (CmpMI->getOpcode() == ARM::tCMPzi8) { + unsigned Reg = CmpMI->getOperand(0).getReg(); + Pred = llvm::getInstrPredicate(CmpMI, PredReg); + if (Pred == ARMCC::AL && + CmpMI->getOperand(1).getImm() == 0 && + isARMLowRegister(Reg)) { + MachineBasicBlock *MBB = Br.MI->getParent(); + MachineInstr *NewBR = + BuildMI(*MBB, CmpMI, Br.MI->getDebugLoc(), TII->get(NewOpc)) + .addReg(Reg).addMBB(DestBB, Br.MI->getOperand(0).getTargetFlags()); + CmpMI->eraseFromParent(); + Br.MI->eraseFromParent(); + Br.MI = NewBR; + BBSizes[MBB->getNumber()] -= 2; + AdjustBBOffsetsAfter(MBB, -2); + ++NumCBZ; + MadeChange = true; + } + } } } diff --git a/lib/Target/ARM/ARMInstrThumb.td b/lib/Target/ARM/ARMInstrThumb.td index 4ceb4eff9b..724366cce3 100644 --- a/lib/Target/ARM/ARMInstrThumb.td +++ b/lib/Target/ARM/ARMInstrThumb.td @@ -278,6 +278,15 @@ let isBranch = 1, isTerminator = 1 in "b$cc\t$target", [/*(ARMbrcond bb:$target, imm:$cc)*/]>; +// Compare and branch on zero / non-zero +let isBranch = 1, isTerminator = 1 in { + def tCBZ : T1I<(outs), (ins tGPR:$cmp, brtarget:$target), IIC_Br, + "cbz\t$cmp, $target", []>; + + def tCBNZ : T1I<(outs), (ins tGPR:$cmp, brtarget:$target), IIC_Br, + "cbnz\t$cmp, $target", []>; +} + //===----------------------------------------------------------------------===// // Load Store Instructions. // |