Hello,
alpha-vms is the only target that does not define
ASM_OUTPUT_ADDR_DIFF_ELT. That makes the code in stmt.c to handle this
case alpha-vms specific. But there is a better way to handle this:
Just mimic -fno-jump-tables if flag_pic is nonzero.
Tested by building a cross-compiler for alpha-dec-vms and verifying
that flag_jump_tables==0 in expand_case.
OK for trunk?
Ciao!
Steven
* config/alpha/vms.h (SUBTARGET_OVERRIDE_OPTIONS): For pic code,
unset flag_jump_tables.
* stmt.c (expand_case): Remove special flag_pic case conditional
on ASM_OUTPUT_ADDR_DIFF_ELT not being defined.
Index: config/alpha/vms.h
===================================================================
--- config/alpha/vms.h (revision 187046)
+++ config/alpha/vms.h (working copy)
@@ -257,7 +257,15 @@ typedef struct {int num_args; enum avms_
#undef ASM_FINAL_SPEC
/* The VMS convention is to always provide minimal debug info
- for a traceback unless specifically overridden. */
+ for a traceback unless specifically overridden.
+
+ Because ASM_OUTPUT_ADDR_DIFF_ELT is not defined for alpha-vms,
+ jump tables cannot be output for PIC code, because you can't put
+ an absolute address in a readonly section. Putting the table in
+ a writable section is a security hole. Therefore, we unset the
+ flag_jump_tables flag, forcing switch statements to be expanded
+ using decision trees. There are probably other ways to address
+ this issue, but using a decision tree is clearly safe. */
#undef SUBTARGET_OVERRIDE_OPTIONS
#define SUBTARGET_OVERRIDE_OPTIONS \
@@ -268,6 +276,8 @@ do {
write_symbols = VMS_DEBUG; \
debug_info_level = DINFO_LEVEL_TERSE; \
} \
+ if (flag_pic == 1) \
+ flag_jump_tables = 0; \
} while (0)
#undef LINK_SPEC
Index: stmt.c
===================================================================
--- stmt.c (revision 187046)
+++ stmt.c (working copy)
@@ -2198,9 +2198,6 @@ expand_case (gimple stmt)
/* RANGE may be signed, and really large ranges will show up
as negative numbers. */
|| compare_tree_int (range, 0) < 0
-#ifndef ASM_OUTPUT_ADDR_DIFF_ELT
- || flag_pic
-#endif
|| !flag_jump_tables
|| TREE_CONSTANT (index_expr)
/* If neither casesi or tablejump is available, we can
