On 06/30/2015 03:06 AM, Eric Botcazou wrote:
I notice the way gcc_assert() is defined in system.h now, the test won't
disappear even when runtime checks are disabled, though you might still
adjust it to avoid any programmer confusion.
It will disappear at run time, see the definition:
/* Include EXPR, so that unused variable warnings do not occur. */
#define gcc_assert(EXPR) ((void)(0 && (EXPR)))
so you really need to use a separate variable.
Oh, yuck -- it never even occurred to me that gcc_assert could be
disabled. I'll bet there are other bugs in GCC due to this very same
problem of depending on its argument being executed for side-effect.
(E.g. take a look at add_stmt_to_eh_lp_fn in tree-eh.c.) Seems like
lousy design to me especially since proper usage doesn't seem to be
documented anywhere.
Anyway, I think the attached patch is what's required to fix the
instance that's my fault. OK? Bernd, if this needs testing, can you help?
-Sandra
2015-06-30 Sandra Loosemore <san...@codesourcery.com>
gcc/
* config/c6x/c6x.c (try_rename_operands): Do not depend on
gcc_assert evaluating its argument for side-effect.
Index: gcc/config/c6x/c6x.c
===================================================================
--- gcc/config/c6x/c6x.c (revision 225202)
+++ gcc/config/c6x/c6x.c (working copy)
@@ -3450,6 +3450,7 @@ try_rename_operands (rtx_insn *head, rtx
int best_reg, old_reg;
vec<du_head_p> involved_chains = vNULL;
unit_req_table new_reqs;
+ bool ok;
for (i = 0, tmp_mask = op_mask; tmp_mask; i++)
{
@@ -3516,7 +3517,8 @@ try_rename_operands (rtx_insn *head, rtx
best_reg =
find_rename_reg (this_head, super_class, &unavailable, old_reg, true);
- gcc_assert (regrename_do_replace (this_head, best_reg));
+ ok = regrename_do_replace (this_head, best_reg);
+ gcc_assert (ok);
count_unit_reqs (new_reqs, head, PREV_INSN (tail));
merge_unit_reqs (new_reqs);
@@ -3529,7 +3531,10 @@ try_rename_operands (rtx_insn *head, rtx
unit_req_imbalance (reqs), unit_req_imbalance (new_reqs));
}
if (unit_req_imbalance (new_reqs) > unit_req_imbalance (reqs))
- gcc_assert (regrename_do_replace (this_head, old_reg));
+ {
+ ok = regrename_do_replace (this_head, old_reg);
+ gcc_assert (ok);
+ }
else
memcpy (reqs, new_reqs, sizeof (unit_req_table));
