sym_push2 optimized for the local_stack case.

    A constant expression removed from the loop.
    If subroutine have 50000+ local variables, then currently
    compilation of such code takes obly 15 sec. Was 2 min.
    gcc-4.1.2 compiles such code in 7 sec. pcc -- 3.44 min.

    A test generator:
    #include <stdio.h>
    int main() {
        puts("#include <stdio.h>"); puts("int main()"); puts("{");
        for (int i = 0; i < 50000; ++i) printf("int X%d = 1;\n", i);
        for (int i = 0; i < 50000; ++i) puts("scanf(\"%d\", &X0);");
        puts("}");
        return 0;
    }

1 files changed, 3 insertions, 3 deletions

diff --git a/tccgen.c b/tccgen.c
index 898856c..48701f9 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -167,9 +167,9 @@ ST_FUNC Sym *sym_push2(Sym **ps, int v, int t, long c)
 {
     Sym *s;
     if (!tcc_state->no_type_redef_check) {
-        if (ps == &local_stack) {
-            for (s = *ps; s && s != scope_stack_bottom; s = s->prev)
-                if (!(v & SYM_FIELD) && (v & ~SYM_STRUCT) < SYM_FIRST_ANOM && s->v == v)
+        if ((ps == &local_stack) && !(v & SYM_FIELD) && (v & ~SYM_STRUCT) < SYM_FIRST_ANOM) {
+            for (s = *ps; s != scope_stack_bottom; s = s->prev)
+                if (s->v == v)
                     tcc_error("incompatible types for redefinition of '%s'",
                               get_tok_str(v, NULL));
         }