bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
+ const MachineRegisterInfo *MRI = &MF.getRegInfo();
const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
// We can't realign the stack if:
// 1. Dynamic stack realignment is explicitly disabled,
// 2. This is a Thumb1 function (it's not useful, so we don't bother), or
// 3. There are VLAs in the function and the base pointer is disabled.
- return (MF.getTarget().Options.RealignStack && !AFI->isThumb1OnlyFunction() &&
- (!MFI->hasVarSizedObjects() || EnableBasePointer));
+ if (!MF.getTarget().Options.RealignStack)
+ return false;
+ if (AFI->isThumb1OnlyFunction())
+ return false;
+ // Stack realignment requires a frame pointer. If we already started
+ // register allocation with frame pointer elimination, it is too late now.
+ if (!MRI->canReserveReg(FramePtr))
+ return false;
+ // We may also need a base pointer if there are dynamic allocas.
+ if (!MFI->hasVarSizedObjects())
+ return true;
+ if (!EnableBasePointer)
+ return false;
+ // A base pointer is required and allowed. Check that it isn't too late to
+ // reserve it.
+ return MRI->canReserveReg(BasePtr);
}
bool ARMBaseRegisterInfo::