shithub: mc

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Make blits take into account type alignment.

    Only use aligned values, conservatively.

--- a/6/isel.c

+++ b/6/isel.c

@@ -372,28 +372,32 @@

     return l;

 }

-static void blit(Isel *s, Loc *to, Loc *from, size_t dstoff, size_t srcoff, size_t sz)

+static void blit(Isel *s, Loc *to, Loc *from, size_t dstoff, size_t srcoff, size_t sz, size_t align)

 {

-    size_t i, m, modesz;

-    Mode modes[] = {ModeQ, ModeL, ModeW, ModeB, ModeNone};

+    static const Mode modes[] = {

+        [8] = ModeQ,

+        [4] = ModeL,

+        [2] = ModeW,

+        [1] = ModeB

+    };

+    size_t i, modesz;

     Loc *sp, *dp; /* pointers to src, dst */

     Loc *tmp, *src, *dst; /* source memory, dst memory */

+    assert(modes[align] != ModeNone);   /* make sure we have a valid alignment */

     sp = inr(s, from);

     dp = inr(s, to);

-    modesz = 8;

     i = 0;

-    for (m = 0; modes[m] != ModeNone; m++) {

-        tmp = locreg(modes[m]);

+    for (modesz = align; modes[modesz] != ModeNone; modesz /= 2) {

+        tmp = locreg(modes[modesz]);

         while (i + modesz <= sz) {

-            src = locmem(i + srcoff, sp, NULL, modes[m]);

-            dst = locmem(i + dstoff, dp, NULL, modes[m]);

+            src = locmem(i + srcoff, sp, NULL, modes[modesz]);

+            dst = locmem(i + dstoff, dp, NULL, modes[modesz]);

             g(s, Imov, src, tmp, NULL);

             g(s, Imov, tmp, dst, NULL);

             i += modesz;

         }

-        modesz /= 2;

     }

 }

@@ -432,7 +436,7 @@

     Loc *retloc, *rsp, *ret;       /* hard-coded registers */

     Loc *stkbump;        /* calculated stack offset */

     int argsz, argoff;

-    size_t i;

+    size_t i, a;

     rsp = locphysreg(Rrsp);

     if (tybase(exprtype(n))->type == Tyvoid) {

@@ -472,7 +476,8 @@

         if (stacknode(n->expr.args[i])) {

             src = locreg(ModeQ);

             g(s, Ilea, arg, src, NULL);

-            blit(s, rsp, src, argoff, 0, size(n->expr.args[i]));

+            a = alignto(1, n->expr.args[i]->expr.type);

+            blit(s, rsp, src, argoff, 0, size(n->expr.args[i]), a);

         } else {

             dst = locmem(argoff, rsp, NULL, arg->mode);

             arg = inri(s, arg);

@@ -497,6 +502,7 @@

     Loc *a, *b, *c, *d, *r;

     Loc *eax, *edx, *cl; /* x86 wants some hard-coded regs */

     Node **args;

+    size_t al;

     args = n->expr.args;

     eax = locphysreg(Reax);

@@ -683,7 +689,8 @@

         case Oblit:

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

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

-            blit(s, a, r, 0, 0, args[2]->expr.args[0]->lit.intval);

+            al = alignto(1, args[0]->expr.type->sub[0]);

+            blit(s, a, r, 0, 0, args[2]->expr.args[0]->lit.intval, al);

             break;

         case Otrunc:

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