Generate PLT thumb stub only when necessary

Generate PLT thumb stub for an ARM PLT entry only when at least one
Thumb instruction branches to that entry.

Warning: To save space, this commit reuses the bit 0 of entries of
got_offsets array. The GOT offset is thus saved in a 31 bit value.
Make sure to divide by 2 (right shift by 1) an offset before storing it
there and conversely to multiply the value by 2 (left shift by 1) before
using it.

1 files changed, 8 insertions, 3 deletions

diff --git a/tcc.h b/tcc.h
index 4e88782..fd4e8da 100644
--- a/tcc.h
+++ b/tcc.h
@@ -33,6 +33,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <limits.h>
 #include <stdarg.h>
 #include <string.h>
 #include <errno.h>
@@ -524,11 +525,15 @@ struct TCCState {
     Section **priv_sections;
     int nb_priv_sections; /* number of private sections */
 
-    /* got handling */
+    /* got & plt handling */
     Section *got;
     Section *plt;
-    unsigned long *got_offsets;
-    int nb_got_offsets;
+    struct {
+        unsigned long plt_thumb_stub:1;
+        /* mult by 2 (or left shift by 1) before use */
+        unsigned long got_offset:(sizeof(long)*CHAR_BIT-1);
+    } *sym_infos;
+    int nb_sym_infos;
     /* give the correspondance from symtab indexes to dynsym indexes */
     int *symtab_to_dynsym;