shithub: mc

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Start stubbing out changes to do spilling

    Our simple codegen currently fails if we need to spill. Fix
    this in a crufty, inelegant, inefficient, but simple way.

--- a/8/asm.h

+++ b/8/asm.h

@@ -89,8 +89,11 @@

     Htab *locs; /* decl id => int stkoff */

     Htab *globls; /* decl id => char *globlname */

-    /* 6 general purpose regs */

+    /* register and spill states */

+    size_t stksz;

     int rtaken[Nreg];

+    Node *rcontains[Nreg];

+    Loc *locmap;

 };

 /* entry points */

@@ -111,13 +114,17 @@

 /* register allocation */

 Loc getreg(Isel *s, Mode m);

-void freeloc(Isel *s, Loc l);

 Loc claimreg(Isel *s, Reg r);

+void freeloc(Isel *s, Loc l);

 void freereg(Isel *s, Reg r);

 extern const char *regnames[];

 extern const Mode regmodes[];

+/* code gen */

+void spill(Isel *s, Reg r);

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

 /* useful functions */

 size_t size(Node *n);

+size_t tysize(Type *t);

 void breakhere();

--- a/8/isel.c

+++ b/8/isel.c

@@ -132,7 +132,7 @@

     return i;

 }

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

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

 {

     va_list ap;

     Insn *i;

--- a/8/reduce.c

+++ b/8/reduce.c

@@ -84,7 +84,7 @@

     return s;

 }

-static size_t tysize(Type *t)

+size_t tysize(Type *t)

 {

     size_t sz;

     size_t i;

--- a/8/regalloc.c

+++ b/8/regalloc.c

@@ -119,6 +119,25 @@

     return l;

 }

+void spill(Isel *s, Reg r)

+{

+    size_t i;

+    Loc l;

+    Node *n;

+

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

+        if (!s->rcontains[i])

+            continue;

+        n = s->rcontains[i];

+        if (exprop(n) != Ovar) {

+            s->stksz += tysize(exprtype(n));

+            locmem(&s->locmap[n->nid], s->stksz, Rebp, Rnone, ModeL);

+            g(s, Imov, locreg(&l, r), &s->locmap[n->nid], NULL);

+        }

+        s->rcontains[i] = NULL;

+    }

+}

+

 Loc getreg(Isel *s, Mode m)

 {

@@ -147,7 +166,7 @@

     int i;

     if (s->rtaken[r])

-        die("Reg %s is already taken", regnames[r]);

+        spill(s, r);

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

         s->rtaken[reginterferes[r][i]] = 1;

     locreg(&l, r);

--- a/parse/parse.h

+++ b/parse/parse.h

@@ -124,6 +124,7 @@

 struct Node {

     int line;

     Ntype type;

+    int nid;

     union {

         struct {

             char  *name;