TC-8 FAQ

Why do we have a TempMap, and not Appel?

$fp or fp, in TC-5 FAQ, for all the details. Pay special attention to converting the temporaries where needed:

  • the flow graph is independent of the temporaries

  • the liveness graph, when computing live-in and live-out sets, must of course convert the “def” and “use” sets

  • the interference graph, when attributing a node number for each temporary (InterferenceGraph::node_of), must allocate the same number to corresponding temporaries (e.g., $fp and fp must bear the same number).

There is another reason to use a TempMap here: to build the liveness graph after register allocation, to check the compiler.

and.tig
1 & 2
tc -sV and.tig
$ tc -sV and.tig

$ echo $?
0
/* Graph Visualization */ digraph "and.main._main.liveness.gv" { node [shape=box]; "0" [label="tc_main:"] "1" [label="# Allocate frame"] "2" [label="l3:"] "3" [label=" li $t0, 1"] "4" [label=" bne $t0, 0, l0"] "5" [label="l1:"] "6" [label="l2:"] "7" [label=" j l4"] "8" [label="l0:"] "9" [label=" j l2"] "10" [label="l4:"] "11" [label="# Deallocate frame"] "12" [label=" jr $ra"] "0" -> "1" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "1" -> "2" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "2" -> "3" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "3" -> "4" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $t0 $v0 $zero"] "5" -> "6" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "6" -> "7" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "8" -> "9" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "10" -> "11" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "11" -> "12" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "4" -> "8" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "4" -> "5" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "7" -> "10" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] "9" -> "6" [label="$fp $ra $s0 $s1 $s2 $s3 $s4 $s5 $s6 $s7 $sp $v0 $zero"] }

and.main._main.liveness.gv