From: David Given <dg@cowlark.com>
Date: Thu, 25 Oct 2018 02:46:19 +0000 (+0200)
Subject: Neuter a ghastly O(n^2) algorithm.
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=0ee1bb575ec0926f3eca14edfcb76f10a35e3dae;p=ack.git

Neuter a ghastly O(n^2) algorithm.
---

diff --git a/mach/proto/mcg/pass_nonlocalphis.c b/mach/proto/mcg/pass_nonlocalphis.c
index 52387c76e..acc359201 100644
--- a/mach/proto/mcg/pass_nonlocalphis.c
+++ b/mach/proto/mcg/pass_nonlocalphis.c
@@ -156,33 +156,38 @@ static void import_ir(struct ir* phi)
 void pass_convert_nonlocal_phis(void)
 {
     int i, j, k;
+    bool need_restart;
 
     graph_reset(&added);
 
     /* If a phi refers to an IR defined in a node which isn't a direct parent,
      * insert phis upstream for it. */
 
-restart:
-    for (i=0; i<dominance.preorder.count; i++)
+    while (!need_restart)
     {
-        current_dest = dominance.preorder.item[i];
+        need_restart = false;
 
-        for (j=0; j<current_dest->irs.count; j++)
+        for (i=0; i<dominance.preorder.count; i++)
         {
-            struct ir* phi = current_dest->irs.item[j];
-            if (phi->opcode == IR_PHI)
+            current_dest = dominance.preorder.item[i];
+
+            for (j=0; j<current_dest->irs.count; j++)
             {
-                for (k=0; k<phi->u.phivalue.count; k++)
+                struct ir* phi = current_dest->irs.item[j];
+                if (phi->opcode == IR_PHI)
                 {
-                    current_ir = phi->u.phivalue.item[k].right;
-                    current_src = current_ir->bb;
-
-                    if (!array_contains(&current_dest->prevs, current_src))
+                    for (k=0; k<phi->u.phivalue.count; k++)
                     {
-                        tracef('I', "I: import of non-local IR $%d into %s from %s\n",
-                            current_ir->id, current_dest->name, current_src->name);
-                        import_ir(phi);
-                        goto restart;
+                        current_ir = phi->u.phivalue.item[k].right;
+                        current_src = current_ir->bb;
+
+                        if (!array_contains(&current_dest->prevs, current_src))
+                        {
+                            tracef('I', "I: import of non-local IR $%d into %s from %s\n",
+                                current_ir->id, current_dest->name, current_src->name);
+                            import_ir(phi);
+                            need_restart = true;
+                        }
                     }
                 }
             }