{ $description "Uses the live intervals in the sequence to assign physical registers to all instructions in the cfg. The live intervals must first have had their physical registers assigned by " { $link allocate-registers } "." } ;
{ $description "Emits a " { $link call-gc## } " instruction and the " { $link reload## } " and " { $link spill## } " instructions it requires. call-gc## aren't counted as sync points, so the instruction requires special handling." } ;
{ $description "Expires all intervals older than the cutoff point. First they are removed from the 'pending-heap' and " { $link pending-interval-assoc } ". Then " { $link spill## } " instructions are inserted for each interval that was removed." } ;
{ $var-description "Mapping from basic blocks to values which are live at the start on all incoming CFG edges. Each value is a sequence of 2-tuples where the first element is the vreg and the second the register or " { $link spill-slot } " which contains its value. It's like " { $link live-ins } " except the registers are physical instead of virtual." } ;
{ $var-description "Mapping from " { $link basic-block } " to an " { $link assoc } " of pairs which are the values that are live at the end. The keys of the pairs are virtual registers and the values are either real registers or spill slots." } ;
{ $values { "vreg""virtual register" } { "reg/spill-slot""a register or a spill slot" } }
{ $description "Translates a virtual register to a physical one. If the vreg is not in the pending set, then it must have been spilled and its spill slot is returned." }
{ $errors "Can throw a " { $link bad-vreg } " error if the vreg is not in the " { $link pending-interval-assoc } " and also doesn't have a spill slot registered." }
"The " { $vocab-link "compiler.cfg.linear-scan.assignment" } " assigns registers to live intervals. Before this compiler pass, all values in the " { $link cfg } " were represented as simple integers called \"virtual registers\" or vregs. In this pass, using the live interval data computed in the register allocation pass (" { $vocab-link "compiler.cfg.linear-scan.allocation" } "), those vregs are translated into physical registers."
"Since there is an infinite number of vregs but the number of physical registers is limited, some values must be spilled. So this pass also handles spilling decisions and inserts " { $link spill## } " and " { $link reload## } " instructions where needed."
