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[PATCH v3] Fix -Os related build and test failures.
On 10/28/2016 10:16 AM, Joseph Myers wrote:
> On Fri, 28 Oct 2016, Carlos O'Donell wrote:
>
>> - Fix math/test-nan-overflow.c which uses malloc but doesn't include
>> stdlib.h.
>
> I don't know what's including <stdlib.h> but not for -Os, but this fix
> should be separate (and committed as obvious).
Checked in.
>> - Define DIAG_IGNORE_Ox_NEEDS_COMMENT and DIAG_IGNORE_Os_NEEDS_COMMENT
>> for use with diagnostics which should be ignored only when optimizing,
>> or when optimizing for size. If we need *Ox* to be finer grained, then
>> we'll have to setup something more complicated, but for now we don't
>> need it.
>
> I don't think we need the -Ox version. glibc is always built with
> optimization, and if we fix things (for better debugging) so that only a
> few bits need to be built with optimization and the rest is correct
> without, it's harmess for the pragmas to be in effect with -O0 even if not
> needed in that case.
v3
- Remove DIAG_IGNORE_Ox_NEEDS_COMMENT.
- Mark for BZ #20729.
- Fix remaining instances of '5.3', and use '5' as the latest version
the warning is seen in.
With Florian's fix for %ebp usage, and this fix for -Werror issues, the
-Os build for i486 is now working again, but still needs bug 19463 and
bug 15105 fixed before it's really working. However, I would consider
marking bug 20729 fixed once this goes in.
No regressions on x86.
OK?
2016-10-28 Carlos O'Donell <carlos@redhat.com>
[BZ #20729]
* include/libc-internal.h (DIAG_IGNORE_Os_NEEDS_COMMENT):
Define.
* iso-2022-cn-ext.c: Include libc-internal.h and ignore
-Wmaybe-uninitialized for BODY macro only for -Os compiles.
* locale/weight.h (findix): Ignore -Wmaybe-uninitialized error
for seq2.back_us and seq1.back_us only for -Os compiles.
* locale/weightwc.h (findix): Likewise.
* nptl_db/thread_dbP.h: Ignore -Wmaybe-uninitialized error for
DB_GET_FIELD_ADDRESS only for -Os compiles.
* resolv/res_send (reopen): Ignore -Wmaybe-uninitialized error
for slen only for -Os compiles.
* string/strcoll_l.c (get_next_seq): Ignore
-Wmaybe-uninitialized for seq2.save_idx and seq1.save_idx only
for -Os compiles.
diff --git a/iconvdata/iso-2022-cn-ext.c b/iconvdata/iso-2022-cn-ext.c
index df5b5df..92970a0 100644
--- a/iconvdata/iso-2022-cn-ext.c
+++ b/iconvdata/iso-2022-cn-ext.c
@@ -27,6 +27,7 @@
#include "cns11643.h"
#include "cns11643l1.h"
#include "cns11643l2.h"
+#include <libc-internal.h>
#include <assert.h>
@@ -394,6 +395,16 @@ enum
#define MIN_NEEDED_OUTPUT TO_LOOP_MIN_NEEDED_TO
#define MAX_NEEDED_OUTPUT TO_LOOP_MAX_NEEDED_TO
#define LOOPFCT TO_LOOP
+/* With GCC 5.3 when compiling with -Os the compiler emits a warning
+ that buf[0] and buf[1] may be used uninitialized. This can only
+ happen in the case where tmpbuf[3] is used, and in that case the
+ write to the tmpbuf[1] and tmpbuf[2] was assured because
+ ucs4_to_cns11643 would have filled in those entries. The difficulty
+ is in getting the compiler to see this logic because tmpbuf[0] is
+ involved in determining the code page and is the indicator that
+ tmpbuf[2] is initialized. */
+DIAG_PUSH_NEEDS_COMMENT;
+DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
#define BODY \
{ \
uint32_t ch; \
@@ -645,6 +656,7 @@ enum
/* Now that we wrote the output increment the input pointer. */ \
inptr += 4; \
}
+DIAG_POP_NEEDS_COMMENT;
#define EXTRA_LOOP_DECLS , int *setp
#define INIT_PARAMS int set = (*setp >> 3) & CURRENT_MASK; \
int ann = (*setp >> 3) & ~CURRENT_MASK
diff --git a/include/libc-internal.h b/include/libc-internal.h
index 7a185bb..2d9096a 100644
--- a/include/libc-internal.h
+++ b/include/libc-internal.h
@@ -111,4 +111,19 @@ extern __typeof (__profile_frequency) __profile_frequency attribute_hidden;
#define DIAG_IGNORE_NEEDS_COMMENT(version, option) \
_Pragma (_DIAG_STR (GCC diagnostic ignored option))
+/* Similar to DIAG_IGNORE_NEEDS_COMMENT the following macro ignores the
+ diagnostic OPTION but only if optimizations for size are enabled.
+ This is required because different warnings may be generated for
+ different optimization levels. For example a key piece of code may
+ only generate a warning when compiled at -Os, but at -O2 you could
+ still want the warning to be enabled to catch errors. In this case
+ you would use DIAG_IGNORE_Os_NEEDS_COMMENT to disable the warning
+ only for -Os. */
+#if __OPTIMIZE_SIZE__
+#define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option) \
+ _Pragma (_DIAG_STR (GCC diagnostic ignored option))
+#else
+#define DIAG_IGNORE_Os_NEEDS_COMMENT(version, option)
+#endif
+
#endif /* _LIBC_INTERNAL */
diff --git a/locale/weight.h b/locale/weight.h
index c99730c..1f61f01 100644
--- a/locale/weight.h
+++ b/locale/weight.h
@@ -61,9 +61,17 @@ findidx (const int32_t *table,
already. */
size_t cnt;
+ /* With GCC 5.3 when compiling with -Os the compiler warns
+ that seq2.back_us, which becomes usrc, might be used
+ uninitialized. This can't be true because we pass a length
+ of -1 for len at the same time which means that this loop
+ never executes. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
if (cp[cnt] != usrc[cnt])
break;
+ DIAG_POP_NEEDS_COMMENT;
if (cnt == nhere)
{
diff --git a/locale/weightwc.h b/locale/weightwc.h
index ab26482..e42ce13 100644
--- a/locale/weightwc.h
+++ b/locale/weightwc.h
@@ -59,9 +59,17 @@ findidx (const int32_t *table,
already. */
size_t cnt;
+ /* With GCC 5.3 when compiling with -Os the compiler warns
+ that seq2.back_us, which becomes usrc, might be used
+ uninitialized. This can't be true because we pass a length
+ of -1 for len at the same time which means that this loop
+ never executes. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
for (cnt = 0; cnt < nhere && cnt < len; ++cnt)
if (cp[cnt] != usrc[cnt])
break;
+ DIAG_POP_NEEDS_COMMENT;
if (cnt == nhere)
{
diff --git a/nptl_db/thread_dbP.h b/nptl_db/thread_dbP.h
index 39c3061..b53f1c1 100644
--- a/nptl_db/thread_dbP.h
+++ b/nptl_db/thread_dbP.h
@@ -160,10 +160,19 @@ extern ps_err_e td_mod_lookup (struct ps_prochandle *ps, const char *modname,
SYM_##type##_FIELD_##field, \
(psaddr_t) 0 + (idx), (ptr), &(var))
+/* With GCC 5.3 when compiling with -Os the compiler emits a warning
+ that slot may be used uninitialized. This is never the case since
+ the dynamic loader initializes the slotinfo list and
+ dtv_slotinfo_list will point slot at the first entry. Therefore
+ when DB_GET_FIELD_ADDRESS is called with a slot for ptr, the slot is
+ always initialized. */
+DIAG_PUSH_NEEDS_COMMENT;
+DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
#define DB_GET_FIELD_ADDRESS(var, ta, ptr, type, field, idx) \
((var) = (ptr), _td_locate_field ((ta), (ta)->ta_field_##type##_##field, \
SYM_##type##_FIELD_##field, \
(psaddr_t) 0 + (idx), &(var)))
+DIAG_POP_NEEDS_COMMENT;
extern td_err_e _td_locate_field (td_thragent_t *ta,
db_desc_t desc, int descriptor_name,
diff --git a/resolv/res_send.c b/resolv/res_send.c
index 6d46bb2..93efb7d 100644
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -664,7 +664,7 @@ send_vc(res_state statp,
a false-positive.
*/
DIAG_PUSH_NEEDS_COMMENT;
- DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
+ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
int resplen;
DIAG_POP_NEEDS_COMMENT;
struct iovec iov[4];
@@ -930,7 +930,16 @@ reopen (res_state statp, int *terrno, int ns)
* error message is received. We can thus detect
* the absence of a nameserver without timing out.
*/
+ /* With GCC 5.3 when compiling with -Os the compiler
+ emits a warning that slen may be used uninitialized,
+ but that is never true. Both slen and
+ EXT(statp).nssocks[ns] are initialized together or
+ the function return -1 before control flow reaches
+ the call to connect with slen. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
if (connect(EXT(statp).nssocks[ns], nsap, slen) < 0) {
+ DIAG_POP_NEEDS_COMMENT;
Aerror(statp, stderr, "connect(dg)", errno, nsap);
__res_iclose(statp, false);
return (0);
diff --git a/string/strcoll_l.c b/string/strcoll_l.c
index 4d1e3ab..065392e 100644
--- a/string/strcoll_l.c
+++ b/string/strcoll_l.c
@@ -24,6 +24,7 @@
#include <stdint.h>
#include <string.h>
#include <sys/param.h>
+#include <libc-internal.h>
#ifndef STRING_TYPE
# define STRING_TYPE char
@@ -170,7 +171,19 @@ get_next_seq (coll_seq *seq, int nrules, const unsigned char *rulesets,
}
}
+ /* With GCC 5.3 when compiling with -Os the compiler complains
+ that idx, taken from seq->idx (seq1 or seq2 from STRCOLL) may
+ be used uninitialized. In general this can't possibly be true
+ since seq1.idx and seq2.idx are initialized to zero in the
+ outer function. Only one case where seq->idx is restored from
+ seq->save_idx might result in an uninitialized idx value, but
+ it is guarded by a sequence of checks against backw_stop which
+ ensures that seq->save_idx was saved to first and contains a
+ valid value. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_Os_NEEDS_COMMENT (5, "-Wmaybe-uninitialized");
len = weights[idx++];
+ DIAG_POP_NEEDS_COMMENT;
/* Skip over indices of previous levels. */
for (int i = 0; i < pass; i++)
{
---
--
Cheers,
Carlos.