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string: Suppress -Wmaybe-unitialized for wordcopy [BZ #19444]

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When compiling with GCC 6+ the sparc build warns that some variables
might be used uninitialized.  However it does not seem the fact, since
the variables are really initialized (and also other targets that use the
same code, like powerpc, do not warn about it).

So suppress the warning for now.

Changes from v1:
* Update patch description and the explanation for the suppresion.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Adhemerval Zanella 2023-01-11 18:27:29 -03:00
parent 8b69e064d4
commit 402853be1d
1 changed files with 24 additions and 0 deletions
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24
string/wordcopy.c
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@ -19,7 +19,19 @@
/* BE VERY CAREFUL IF YOU CHANGE THIS CODE...! */
#include <stddef.h>
#include <libc-diag.h>
/* Compiling with -O1 might warn that 'a2' and 'a3' may be used
uninitialized. There are only two ways to arrive at labels 'do4', 'do3'
or 'do1', all of which use 'a2' or 'a3' in the MERGE macro: either from
the earlier switch case statement or via a loop iteration. In all cases
the switch statement or previous loop sets both 'a2' and 'a3'.
Since the usage is within the MERGE macro we disable the
warning in the definition, but only in this file. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (6, "-Wmaybe-uninitialized");
#include <memcopy.h>
DIAG_POP_NEEDS_COMMENT;
/* _wordcopy_fwd_aligned -- Copy block beginning at SRCP to
block beginning at DSTP with LEN `op_t' words (not LEN bytes!).
@ -94,7 +106,15 @@ WORDCOPY_FWD_ALIGNED (long int dstp, long int srcp, size_t len)
{
do8:
a0 = ((op_t *) srcp)[0];
/* Compiling with -O1 may warn that 'a1' may be used uninitialized.
There are only two ways to arrive at label 'do8' and they are via a
do-while loop iteration or directly via the earlier switch 'case 1:'
case. The switch case always sets 'a1' and all previous loop
iterations will also have set 'a1' before the use. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (6, "-Wmaybe-uninitialized");
((op_t *) dstp)[0] = a1;
DIAG_POP_NEEDS_COMMENT;
do7:
a1 = ((op_t *) srcp)[1];
((op_t *) dstp)[1] = a0;
@ -291,7 +311,11 @@ WORDCOPY_BWD_ALIGNED (long int dstp, long int srcp, size_t len)
{
do8:
a0 = ((op_t *) srcp)[7];
/* Check the comment on WORDCOPY_FWD_ALIGNED. */
DIAG_PUSH_NEEDS_COMMENT;
DIAG_IGNORE_NEEDS_COMMENT (6, "-Wmaybe-uninitialized");
((op_t *) dstp)[7] = a1;
DIAG_POP_NEEDS_COMMENT;
do7:
a1 = ((op_t *) srcp)[6];
((op_t *) dstp)[6] = a0;