if (!Pred->empty()) {
MachineInstr *LastMI = &*Pred->rbegin();
if (LastMI->getOpcode() == ARM::t2Bcc) {
- MachineBasicBlock::iterator CmpMI = LastMI;
- if (CmpMI != Pred->begin()) {
- --CmpMI;
- if (CmpMI->getOpcode() == ARM::tCMPi8 ||
- CmpMI->getOpcode() == ARM::t2CMPri) {
- unsigned Reg = CmpMI->getOperand(0).getReg();
- unsigned PredReg = 0;
- ARMCC::CondCodes P = getInstrPredicate(*CmpMI, PredReg);
- if (P == ARMCC::AL && CmpMI->getOperand(1).getImm() == 0 &&
- isARMLowRegister(Reg))
- return false;
- }
- }
+ const TargetRegisterInfo *TRI = &getRegisterInfo();
+ MachineInstr *CmpMI = findCMPToFoldIntoCBZ(LastMI, TRI);
+ if (CmpMI)
+ return false;
}
}
}
{MO_NONLAZY, "arm-nonlazy"}};
return makeArrayRef(TargetFlags);
}
+
+bool llvm::registerDefinedBetween(unsigned Reg,
+ MachineBasicBlock::iterator From,
+ MachineBasicBlock::iterator To,
+ const TargetRegisterInfo *TRI) {
+ for (auto I = From; I != To; ++I)
+ if (I->modifiesRegister(Reg, TRI))
+ return true;
+ return false;
+}
+
+MachineInstr *llvm::findCMPToFoldIntoCBZ(MachineInstr *Br,
+ const TargetRegisterInfo *TRI) {
+ // Search backwards to the instruction that defines CSPR. This may or not
+ // be a CMP, we check that after this loop. If we find another instruction
+ // that reads cpsr, we return nullptr.
+ MachineBasicBlock::iterator CmpMI = Br;
+ while (CmpMI != Br->getParent()->begin()) {
+ --CmpMI;
+ if (CmpMI->modifiesRegister(ARM::CPSR, TRI))
+ break;
+ if (CmpMI->readsRegister(ARM::CPSR, TRI))
+ break;
+ }
+
+ // Check that this inst is a CMP r[0-7], #0 and that the register
+ // is not redefined between the cmp and the br.
+ if (CmpMI->getOpcode() != ARM::tCMPi8 && CmpMI->getOpcode() != ARM::t2CMPri)
+ return nullptr;
+ unsigned Reg = CmpMI->getOperand(0).getReg();
+ unsigned PredReg = 0;
+ ARMCC::CondCodes Pred = getInstrPredicate(*CmpMI, PredReg);
+ if (Pred != ARMCC::AL || CmpMI->getOperand(1).getImm() != 0)
+ return nullptr;
+ if (!isARMLowRegister(Reg))
+ return nullptr;
+ if (registerDefinedBetween(Reg, CmpMI->getNextNode(), Br, TRI))
+ return nullptr;
+
+ return &*CmpMI;
+}
--- /dev/null
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=thumbv7m-none-eabi -run-pass=if-converter -o - %s | FileCheck %s
+
+--- |
+ define i32 @f1(i32 %x) #0 { ret i32 %x }
+ define i32 @f2(i32 %x) #0 { ret i32 %x }
+ define i32 @f3(i32 %x) #0 { ret i32 %x }
+ declare i32 @fn(i32 %x) #0
+
+ attributes #0 = { minsize nounwind optsize }
+
+...
+---
+name: f1
+tracksRegLiveness: true
+liveins:
+ - { reg: '$r0', virtual-reg: '' }
+stack:
+ - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$lr', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$r7', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body: |
+ ; CHECK-LABEL: name: f1
+ ; CHECK: bb.0:
+ ; CHECK: liveins: $r0, $lr, $r7
+ ; CHECK: t2CMPri killed renamable $r0, 1, 14, $noreg, implicit-def $cpsr
+ ; CHECK: tBX_RET 1, killed $cpsr
+ ; CHECK: $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ ; CHECK: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $lr, -4
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $r7, -8
+ ; CHECK: $r0 = t2MOVi 0, 14, $noreg, $noreg
+ ; CHECK: tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ ; CHECK: $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ ; CHECK: tBX_RET 14, $noreg
+ bb.0:
+ successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ liveins: $r0, $lr, $r7
+
+ t2CMPri killed renamable $r0, 1, 14, $noreg, implicit-def $cpsr
+ t2Bcc %bb.2, 1, killed $cpsr
+
+ bb.1:
+ liveins: $r7, $lr
+
+ $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ frame-setup CFI_INSTRUCTION offset $lr, -4
+ frame-setup CFI_INSTRUCTION offset $r7, -8
+ $r0 = t2MOVi 0, 14, $noreg, $noreg
+ tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ tBX_RET 14, $noreg
+
+ bb.2:
+ liveins: $lr, $r7
+
+ tBX_RET 14, $noreg
+
+...
+---
+name: f2
+tracksRegLiveness: true
+liveins:
+ - { reg: '$r0', virtual-reg: '' }
+stack:
+ - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$lr', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$r7', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body: |
+ ; CHECK-LABEL: name: f2
+ ; CHECK: bb.0:
+ ; CHECK: successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ ; CHECK: liveins: $r0, $lr, $r7
+ ; CHECK: t2CMPri killed renamable $r0, 0, 14, $noreg, implicit-def $cpsr
+ ; CHECK: t2Bcc %bb.2, 1, killed $cpsr
+ ; CHECK: bb.1:
+ ; CHECK: liveins: $r7, $lr
+ ; CHECK: $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ ; CHECK: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $lr, -4
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $r7, -8
+ ; CHECK: $r0 = t2MOVi 0, 14, $noreg, $noreg
+ ; CHECK: tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ ; CHECK: $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ ; CHECK: tBX_RET 14, $noreg
+ ; CHECK: bb.2:
+ ; CHECK: liveins: $lr, $r7
+ ; CHECK: tBX_RET 14, $noreg
+ bb.0:
+ successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ liveins: $r0, $lr, $r7
+
+ t2CMPri killed renamable $r0, 0, 14, $noreg, implicit-def $cpsr
+ t2Bcc %bb.2, 1, killed $cpsr
+
+ bb.1:
+ liveins: $r7, $lr
+
+ $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ frame-setup CFI_INSTRUCTION offset $lr, -4
+ frame-setup CFI_INSTRUCTION offset $r7, -8
+ $r0 = t2MOVi 0, 14, $noreg, $noreg
+ tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ tBX_RET 14, $noreg
+
+ bb.2:
+ liveins: $lr, $r7
+
+ tBX_RET 14, $noreg
+
+...
+---
+name: f3
+tracksRegLiveness: true
+liveins:
+ - { reg: '$r0', virtual-reg: '' }
+stack:
+ - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$lr', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
+ stack-id: 0, callee-saved-register: '$r7', callee-saved-restored: true,
+ debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body: |
+ ; CHECK-LABEL: name: f3
+ ; CHECK: bb.0:
+ ; CHECK: successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ ; CHECK: liveins: $r0, $lr, $r7
+ ; CHECK: t2CMPri killed renamable $r0, 0, 14, $noreg, implicit-def $cpsr
+ ; CHECK: $r1 = t2MOVi 0, 14, $noreg, $noreg
+ ; CHECK: t2Bcc %bb.2, 1, killed $cpsr
+ ; CHECK: bb.1:
+ ; CHECK: liveins: $r7, $lr
+ ; CHECK: $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ ; CHECK: frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $lr, -4
+ ; CHECK: frame-setup CFI_INSTRUCTION offset $r7, -8
+ ; CHECK: $r0 = t2MOVi 0, 14, $noreg, $noreg
+ ; CHECK: tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ ; CHECK: $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ ; CHECK: tBX_RET 14, $noreg
+ ; CHECK: bb.2:
+ ; CHECK: liveins: $lr, $r7
+ ; CHECK: tBX_RET 14, $noreg
+ bb.0:
+ successors: %bb.1(0x40000000), %bb.2(0x40000000)
+ liveins: $r0, $lr, $r7
+
+ t2CMPri killed renamable $r0, 0, 14, $noreg, implicit-def $cpsr
+ $r1 = t2MOVi 0, 14, $noreg, $noreg
+ t2Bcc %bb.2, 1, killed $cpsr
+
+ bb.1:
+ liveins: $r7, $lr
+
+ $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r7, killed $lr
+ frame-setup CFI_INSTRUCTION def_cfa_offset 8
+ frame-setup CFI_INSTRUCTION offset $lr, -4
+ frame-setup CFI_INSTRUCTION offset $r7, -8
+ $r0 = t2MOVi 0, 14, $noreg, $noreg
+ tBL 14, $noreg, @fn, csr_aapcs, implicit-def dead $lr, implicit $sp, implicit $r0, implicit-def $sp, implicit-def dead $r0
+ $sp = t2LDMIA_UPD $sp, 14, $noreg, def $r7, def $lr
+ tBX_RET 14, $noreg
+
+ bb.2:
+ liveins: $lr, $r7
+
+ tBX_RET 14, $noreg
+
+...