c: handle more static eval edgecases for int -> ptr

sqlite3 was falling back to `((void*)&((char*)0)[X])` for INT_TO_PTR,
which this handles now.

3 files changed, 29 insertions, 5 deletions

diff --git a/c/c.c b/c/c.c
index d79439a..5ff2041 100644
--- a/c/c.c
+++ b/c/c.c
@@ -788,7 +788,7 @@ ppostfixopers(struct comp *cm, struct expr *ex)
       rhs = commaexpr(cm);
       span = ex->span;
       if (!joinspan(&span.ex, tk.span.ex) || !joinspan(&span.ex, ex->span.ex)
-       || (peek(cm, &tk2), !joinspan(&span.ex, tk.span.ex)))
+       || (peek(cm, &tk), !joinspan(&span.ex, tk.span.ex)))
          span = tk.span;
       expect(cm, ']', NULL);
 
diff --git a/c/eval.c b/c/eval.c
index c9208b8..b6dad3a 100644
--- a/c/eval.c
+++ b/c/eval.c
@@ -177,12 +177,27 @@ isaddrconst(struct expr *ex)
       return 1;
    if (isglobsym(ex) && in_range(ex->ty.t, TYARRAY, TYFUNC))
       return 1;
-   if (ex->t == ESUB)
-      return isglobsym(&ex->sub[0]) && isint(ex->sub[1].ty) && eval(&ex->sub[1], EVSTATICINI);
-   if (ex->t == EADD) {
+   if (ex->t == ESUB) {
+      if (isaddrconst(&ex->sub[0]) && isint(ex->sub[1].ty) && eval(&ex->sub[1], EVSTATICINI)) {
+         assert(ex->sub[1].t == ENUMLIT);
+         if (eval(&ex->sub[0], EVSTATICINI) && ex->sub[0].t == ENUMLIT) {
+            /* handles (char *)10 - 5 */
+            ex->u = ex->sub[0].u - ex->sub[1].u * typesize(typechild(ex->sub[0].ty));
+            ex->t = ENUMLIT;
+         }
+         return 1;
+      }
+   } else if (ex->t == EADD) {
       for (int swp = 0; swp < 2; ++swp)
-         if (isglobsym(&ex->sub[swp]) && isint(ex->sub[swp^1].ty) && eval(&ex->sub[swp^1], EVSTATICINI))
+         if (isaddrconst(&ex->sub[swp]) && isint(ex->sub[swp^1].ty) && eval(&ex->sub[swp^1], EVSTATICINI)) {
+            assert(ex->sub[swp^1].t == ENUMLIT);
+            if (eval(&ex->sub[swp], EVSTATICINI) && ex->sub[swp].t == ENUMLIT) {
+               /* handles (char *)1234 + 5678 */
+               ex->u = ex->sub[swp].u + ex->sub[swp^1].u * typesize(typechild(ex->sub[swp].ty));
+               ex->t = ENUMLIT;
+            }
             return 1;
+         }
    }
    return 0;
 }
diff --git a/test/15-reloc.c b/test/15-reloc.c
index cd91fd0..713e98d 100644
--- a/test/15-reloc.c
+++ b/test/15-reloc.c
@@ -3,6 +3,7 @@
 1.3
 5
 ok
+0x55, 0x6, 5
 */
 
 const void *const relro = &relro;
@@ -22,9 +23,17 @@ int (*(getputs(void)))(const char *) {
    return t;
 }
 
+static char *int2ptr[] = {
+   (void *)&*((char*)0 + 0x55),
+   (void *)&((short*)0)[0x3],
+   (void *)&*((char*)7 - 2),
+};
+
 #include <stdio.h>
+#include <stdint.h>
 int main() {
    printf("%g\n", get_value(2));
    printf("%d\n", ou(2));
    getputs()("ok");
+   printf("%p, %p, %d\n", int2ptr[0], int2ptr[1], (int)(intptr_t)int2ptr[2]);
 }