question: public static void allocateSpaceForSysCall ( IR ir ) { StackManager sm = ( StackManager ) ir . stackManager ; int nToSave = PhysicalRegisterSet . getNumberOfNonvolatileGPRs ( ) + 1 ; sm . allocateSpaceForSysCall ( nToSave ) ; }
target:  We have to save/restore the non-volatile registers around syscalls, to protect ourselves from malicious C compilers and Linux kernels.<p> Although the register allocator is not yet ready to insert these spills, allocate space on the stack in preparation.<p> For now, we naively save/restore all nonvolatiles.