> Hooks for predication support.
yay!
> +bool ARMInstrInfo::isPredicatable(MachineInstr *MI) const {
> + const TargetInstrDescriptor *TID = MI->getInstrDescriptor();
> + if (TID->Flags & M_PREDICATED)
> + return true;
> +
> + unsigned Opc = MI->getOpcode();
> + return Opc == ARM::B || Opc == ARM::tB;
> +}
> +
> +void ARMInstrInfo::PredicateInstruction(MachineInstr *MI,
> + std::vector<MachineOperand>
> &Cond) const {
> + unsigned Opc = MI->getOpcode();
> + if (Opc == ARM::B || Opc == ARM::tB) {
> + MI->setInstrDescriptor(get(Opc == ARM::B ? ARM::Bcc :
> ARM::tBcc));
> + MI->addImmOperand(Cond[0].getImmedValue());
> + return;
> + }
> +
> + MachineOperand *PMO = MI->findFirstPredOperand();
> + PMO->setImm(Cond[0].getImmedValue());
> +}
I don't think there is any reason for this to be virtual and target-
specific. In particular, can you please model B/tB the same way PPC
handles branches (where an uncond branch is just a conditional branch
where the condition is set to 'always')? That way, you don't need a
special case, isPredicatable doesn't need to be virtual, and each
target doesn't need to implement PredicateInstruction.
-Chris
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