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Stub in callee save registers.

    Don't enable them since they're broken, but stub them in.

--- a/6/asm.h

+++ b/6/asm.h

@@ -4,7 +4,7 @@

 #define Wordsz 4                /* the size of a "natural int" */

 #define Ptrsz 8                 /* the size of a machine word (ie, pointer size) */

 #define K 14                    /* the number of allocatable registers */

-#define Nsaved 14               /* number of registers saved in the ABI */

+#define Nsaved 13               /* number of registers saved in the ABI */

 typedef size_t regid;

@@ -195,7 +195,6 @@

 void iprintf(FILE *fd, Insn *insn);

 /* emitting instructions */

-void g(Isel *s, AsmOp op, ...);

 Insn *mkinsn(AsmOp op, ...);

 /* register allocation */

--- a/6/isel.c

+++ b/6/isel.c

@@ -131,7 +131,7 @@

     return i;

 }

-static void g(Isel *s, AsmOp op, ...)

+Insn *mkinsn(AsmOp op, ...)

 {

     va_list ap;

     Insn *i;

@@ -139,6 +139,17 @@

     va_start(ap, op);

     i = mkinsnv(op, ap);

     va_end(ap);

+    return i;

+}

+

+void g(Isel *s, AsmOp op, ...)

+{

+    va_list ap;

+    Insn *i;

+

+    va_start(ap, op);

+    i = mkinsnv(op, ap);

+    va_end(ap);

     if (debugopt['i']) {

         printf("GEN ");

         iprintf(stdout, i);

@@ -749,18 +760,44 @@

     }

 }

+Reg savedregs[] = {

+    Rrcx,

+    Rrdx,

+    Rrbx,

+    Rrsi,

+    Rrdi,

+    Rr8,

+    Rr9,

+    Rr10,

+    Rr11,

+    Rr12,

+    Rr13,

+    Rr14,

+    Rr15

+};

+

 static void prologue(Isel *s, size_t sz)

 {

     Loc *rsp;

     Loc *rbp;

     Loc *stksz;

+    //size_t i;

     rsp = locphysreg(Rrsp);

     rbp = locphysreg(Rrbp);

     stksz = loclit(sz, ModeQ);

+    /* enter function */

     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 */

 }

@@ -768,6 +805,7 @@

 {

     Loc *rsp, *rbp;

     Loc *ret;

+    //size_t i;

     rsp = locphysreg(Rrsp);

     rbp = locphysreg(Rrbp);

@@ -775,6 +813,12 @@

         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

@@ -996,8 +996,10 @@

     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);