mescc: Tinycc support: ((unsigned char*)str)[0].

* module/language/c99/compiler.mes (expr->accu): Consider size of
  expr array deref.
* stage0/x86.M1 (movzbl_0x32(%ebp),%eax): New define.
* scaffold/tests/7d-cast-char.c: Test it.

make.scm

@@ -162,7 +162,8 @@ exec ${GUILE-guile} --no-auto-compile -L . -L guile -C . -C guile -s "$0" ${1+"$
    "79-int-array"
    "7a-struct-char-array"
    "7b-struct-int-array"
-   "7c-dynarray"))
+   "7c-dynarray"
+   "7d-cast-char"))
 
 (add-target (group "check-scaffold-tests/7" #:dependencies (filter (target-prefix? "check-scaffold/tests/7") %targets)))
 

module/language/c99/compiler.mes

@@ -592,8 +592,12 @@
 
         ;; <expr>[baz]
         ((array-ref ,index ,array)
-         (let ((info ((expr->accu* info) o)))
-           (append-text info (wrap-as (i386:mem->accu)))))
+         (let* ((info ((expr->accu* info) o))
+                (ptr (expr->pointer info array))
+                (size (if (= ptr 1) (expr->size info array)
+                          4)))
+           (append-text info (wrap-as (if (= size 1) (i386:byte-mem->accu)
+                                          (i386:mem->accu))))))
 
         ;; bar.f.i
         ((d-sel (ident ,field1) (d-sel (ident ,field0) (p-expr (ident ,struct0))))

scaffold/tests/7d-cast-char.c

@@ -0,0 +1,33 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * Mes --- Maxwell Equations of Software
+ * Copyright © 2017 Jan Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of Mes.
+ *
+ * Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "30-test.i"
+
+int
+test ()
+{
+  char *s = "int";
+  char c = s[0];
+  if (c != 'i') return 1;
+  int i = ((unsigned char *)s)[0];
+  if (i != 'i') return 2;
+
+  return 0;
+}

stage0/x86.M1

@@ -120,6 +120,7 @@ DEFINE movzbl_%dl,%edx 0fb6d2
 DEFINE movzbl_(%eax),%eax 0fb600
 DEFINE movzbl_(%eax),%edx 0fb610
 DEFINE movzbl_(%edx),%edx 0fb612
+DEFINE movzbl_0x32(%ebp),%eax 0fb685
 DEFINE movzbl_0x8(%ebp),%eax 0fb645
 DEFINE movzbl_0x8(%ebp),%edx 0fb655
 DEFINE mul____%edx f7e2