Compute the degrees while building the interference graph.

This speeds up the register allocator and allows for further optimizations.



git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@13142 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

asmcomp/coloring.ml

@@ -47,20 +47,10 @@ let find_degree reg =
   if reg.spill then () else begin
     let cl = Proc.register_class reg in
     let avail_regs = Proc.num_available_registers.(cl) in
-    if avail_regs = 0 then
-      (* Don't bother computing the degree if there are no regs
-         in this class *)
+    if reg.degree < avail_regs then
       unconstrained := Reg.Set.add reg !unconstrained
-    else begin
-      let deg = ref 0 in
-      List.iter
-        (fun r -> if not r.spill && Proc.register_class r = cl then incr deg)
-        reg.interf;
-      reg.degree <- !deg;
-      if !deg >= avail_regs
-      then constrained := Reg.Set.add reg !constrained
-      else unconstrained := Reg.Set.add reg !unconstrained
-    end
+    else
+      constrained := Reg.Set.add reg !constrained
   end
 
 (* Remove a register from the interference graph *)

asmcomp/interf.ml

@@ -29,13 +29,20 @@ let build_graph fundecl =
 
   (* Record an interference between two registers *)
   let add_interf ri rj =
+    let update rs rt =
+      if rs.loc = Unknown then begin
+        rs.interf <- rt :: rs.interf;
+        if not rt.spill
+        && Proc.register_class rs = Proc.register_class rt
+        then rs.degree <- rs.degree + 1
+      end in
     let i = ri.stamp and j = rj.stamp in
     if i <> j then begin
       let p = if i < j then (i, j) else (j, i) in
       if not(IntPairSet.mem p !mat) then begin
         mat := IntPairSet.add p !mat;
-        if ri.loc = Unknown then ri.interf <- rj :: ri.interf;
-        if rj.loc = Unknown then rj.interf <- ri :: rj.interf
+        update ri rj;
+        update rj ri
       end
     end in