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Work on moving to callee save convention.

    This breaks things badly; We have a register allocator bug.

--- a/6/isel.c

+++ b/6/isel.c

@@ -781,7 +781,7 @@

     Loc *rsp;

     Loc *rbp;

     Loc *stksz;

-    //size_t i;

+    size_t i;

     rsp = locphysreg(Rrsp);

     rbp = locphysreg(Rrbp);

@@ -790,13 +790,11 @@

     g(s, Ipush, rbp, NULL);

     g(s, Imov, rsp, rbp, NULL);

     g(s, Isub, stksz, rsp, NULL);

-#if 0

     /* save registers */

     for (i = 0; i < sizeof(savedregs)/sizeof(savedregs[0]); i++) {

         s->calleesave[i] = locreg(ModeQ);

         g(s, Imov, locphysreg(savedregs[i]), s->calleesave[i], NULL);

     }

-#endif

     s->stksz = stksz; /* need to update if we spill */

 }

@@ -805,7 +803,7 @@

 {

     Loc *rsp, *rbp;

     Loc *ret;

-    //size_t i;

+    size_t i;

     rsp = locphysreg(Rrsp);

     rbp = locphysreg(Rrbp);

@@ -813,12 +811,10 @@

         ret = loc(s, s->ret);

         g(s, Imov, ret, coreg(Rax, ret->mode), NULL);

     }

-#if 0

     /* restore registers */

     for (i = 0; i < Nsaved; i++)

         g(s, Imov, s->calleesave[i], locphysreg(savedregs[i]), NULL);

     /* leave function */

-#endif

     g(s, Imov, rbp, rsp, NULL);

     g(s, Ipop, rbp, NULL);

     g(s, Iret, NULL);

--- a/6/ra.c

+++ b/6/ra.c

@@ -18,6 +18,7 @@

     int r[Maxarg + 1]; /* list of registers used implicitly by instruction */

 };

+void wlprint(FILE *fd, char *name, Loc **wl, size_t nwl);

 static void printedge(FILE *fd, char *msg, size_t a, size_t b);

 /* tables of uses/defs by instruction */

@@ -329,6 +330,16 @@

     s->degree = zalloc(maxregid * sizeof(int));

     s->rmoves = zalloc(maxregid * sizeof(Loc **));

     s->nrmoves = zalloc(maxregid * sizeof(size_t));

+

+    /* Initialize the degrees of prepainted registers */

+    bsput(s->prepainted, 0);

+    s->degree[0] = 1<<16;

+    for (i = 0; i < maxregid; i++) {

+        if (locmap[i]->reg.colour) {

+            bsput(s->prepainted, i);

+            s->degree[i] = 1<<16;

+        }

+    }

 }

 static void build(Isel *s)

@@ -393,7 +404,6 @@

                 goto next;

         if (bshas(s->coalesced, r))

             goto next;

-        assert(r < maxregid);

         *m = r;

         return 1;

 next:

@@ -515,9 +525,12 @@

         return;

     if (s->degree[u] >= K)

         return;

-    for (i = 0; i < s->nwlfreeze; i++)

-        if (s->wlfreeze[i]->reg.id == u)

+    for (i = 0; i < s->nwlfreeze; i++) {

+        if (s->wlfreeze[i]->reg.id == u) {

             ldel(&s->wlfreeze, &s->nwlfreeze, i);

+            break;

+        }

+    }

     lappend(&s->wlsimp, &s->nwlsimp, locmap[u]);

 }

@@ -562,7 +575,7 @@

         return 1;

     /* if it is, are the adjacent nodes ok to combine with this? */

-    for (t = 0; adjiter(s, u, &t); t++)

+    for (t = 0; adjiter(s, v, &t); t++)

         if (!ok(s, t, u))

             return 0;

     return 1;

@@ -617,6 +630,9 @@

         addedge(s, t, u);

         decdegree(s, t);

     }

+    printf("Degree ");

+    locprint(stdout, locmap[u], 'x');

+    printf(" = %d\n", s->degree[u]);

     if (s->degree[u] >= K && wlhas(s->wlfreeze, s->nwlfreeze, u, &idx)) {

         ldel(&s->wlfreeze, &s->nwlfreeze, idx);

         lappend(&s->wlspill, &s->nwlspill, locmap[u]);

@@ -718,7 +734,6 @@

     /* FIXME: pick a better heuristic for spilling */

     m = NULL;

     for (i = 0; i < s->nwlspill; i++) {

-        printf("Trying to spill %zd\n", s->wlspill[i]->reg.id);

         if (!bshas(s->shouldspill, s->wlspill[i]->reg.id))

             continue;

         m = s->wlspill[i];

@@ -990,19 +1005,14 @@

 void regalloc(Isel *s)

 {

-    size_t i;

     int spilled;

+    size_t i;

     s->prepainted = mkbs();

     s->shouldspill = mkbs();

     s->neverspill = mkbs();

-#if 0

     for (i = 0; i < Nsaved; i++)

         bsput(s->shouldspill, s->calleesave[i]->reg.id);

-#endif

-    for (i = 0; i < maxregid; i++)

-        if (locmap[i]->reg.colour)

-            bsput(s->prepainted, i);

     do {

         setup(s);

         liveness(s);

@@ -1029,6 +1039,21 @@

     bsfree(s->neverspill);

 }

+void wlprint(FILE *fd, char *name, Loc **wl, size_t nwl)

+{

+    size_t i;

+    char *sep;

+

+    sep = "";

+    fprintf(fd, "%s = [", name);

+    for (i = 0; i < nwl; i++) {

+        fprintf(fd, "%s", sep);

+        locprint(fd, wl[i], 'x');

+        sep = ",";

+    }

+    fprintf(fd, "]\n");

+}

+

 static void setprint(FILE *fd, Bitset *s)

 {

     char *sep;

@@ -1087,11 +1112,18 @@

     char *sep;

     Asmbb *bb;

-    fprintf(fd, "IGRAPH ----- \n");

-    for (i = 0; i < maxregid; i++) {

-        for (j = i; j < maxregid; j++) {

-            if (gbhasedge(s, i, j))

-                printedge(stdout, "", i, j);

+    fprintf(fd, "WORKLISTS -- \n");

+    wlprint(stdout, "spill", s->wlspill, s->nwlspill);

+    wlprint(stdout, "simp", s->wlsimp, s->nwlsimp);

+    wlprint(stdout, "freeze", s->wlfreeze, s->nwlfreeze);

+    /* noisy to dump this all the time; only dump for higher debug levels */

+    if (debugopt['r'] > 2) {

+        fprintf(fd, "IGRAPH ----- \n");

+        for (i = 0; i < maxregid; i++) {

+            for (j = i; j < maxregid; j++) {

+                if (gbhasedge(s, i, j))

+                    printedge(stdout, "", i, j);

+            }

         }

     }

     fprintf(fd, "ASM -------- \n");