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Add inri constraint (in register or immediate)

    Prevents an imm -> reg -> mem move in some cases.

--- a/8/isel.c

+++ b/8/isel.c

@@ -232,7 +232,8 @@

     g(s, Imov, a, b, NULL);

 }

-Loc inreg(Isel *s, Loc a)

+/* ensures that a location is within a reg */

+Loc inr(Isel *s, Loc a)

 {

     Loc r;

@@ -243,6 +244,14 @@

     return r;

 }

+/* ensures that a location is within a reg or an imm */

+Loc inri(Isel *s, Loc a)

+{

+    if (a.type == Locreg || a.type == Loclit)

+        return a;

+    else

+        return inr(s, a);

+}

 /* If we're testing equality, etc, it's a bit silly

  * to generate the test, store it to a bite, expand it

@@ -288,7 +297,7 @@

     a = selexpr(s, x);

     b = selexpr(s, y);

-    a = inreg(s, a);

+    a = inri(s, a);

     g(s, op, &b, &a, NULL);

     return a;

 }

@@ -339,9 +348,11 @@

             return r;

         case Oasn:  /* relabel */

+            die("Unimplemented op %s", opstr(exprop(n))); break;

         case Ostor: /* reg -> mem */

             a = selexpr(s, args[0]);

             b = selexpr(s, args[1]);

+            b = inri(s, b);

             stor(s, &b, &a);

             r = b;

             break;

@@ -514,6 +525,7 @@

       g(s, Imov, &ret, &eax, NULL);

     g(s, Imov, &ebp, &esp, NULL);

     g(s, Ipop, &ebp, NULL);

+    g(s, Iret, NULL);

 }

 /* genasm requires all nodes in 'nl' to map cleanly to operations that are