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Re: [PATCH] Avoid uninit warnings with PR79345 fix
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Richard Biener <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 21 Feb 2017 15:15:45 +0100
- Subject: Re: [PATCH] Avoid uninit warnings with PR79345 fix
- Authentication-results: sourceware.org; auth=none
- References: <alpine.LSU.2.20.1702211452140.8538@zhemvz.fhfr.qr>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Tue, Feb 21, 2017 at 02:53:32PM +0100, Richard Biener wrote:
>
> The following fixes a bit-load.c bug as well as avoids the warnings
> for two other cases.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu.
>
> Ok?
>
> Thanks,
> Richard.
>
> 2017-02-21 Richard Biener <rguenther@suse.de>
>
> * bt-load.c (compute_defs_uses_and_gen): Clear call_saved.
> * fixed-value.c (fixed_from_string): Use wi::ulow and wi::uhigh.
> (fixed_convert_from_real): Likewise.
> * ipa-cp.c (ipcp_store_vr_results): Do not uselessly initialize
> VR_VARYING min/max.
>
> Index: gcc/bt-load.c
> ===================================================================
> --- gcc/bt-load.c (revision 245620)
> +++ gcc/bt-load.c (working copy)
> @@ -543,6 +543,7 @@ compute_defs_uses_and_gen (btr_heap_t *a
> int i;
>
> /* Check for sibcall. */
> + CLEAR_HARD_REG_SET (call_saved);
> if (GET_CODE (pat) == PARALLEL)
> for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
> if (ANY_RETURN_P (XVECEXP (pat, 0, i)))
Why do we warn here?
HARD_REG_SET *clobbered = &call_used_reg_set;
HARD_REG_SET call_saved;
rtx pat = PATTERN (insn);
int i;
/* Check for sibcall. */
if (GET_CODE (pat) == PARALLEL)
for (i = XVECLEN (pat, 0) - 1; i >= 0; i--)
if (ANY_RETURN_P (XVECEXP (pat, 0, i)))
{
COMPL_HARD_REG_SET (call_saved,
call_used_reg_set);
clobbered = &call_saved;
}
for (regno = first_btr; regno <= last_btr; regno++)
if (TEST_HARD_REG_BIT (*clobbered, regno))
note_btr_set (regno_reg_rtx[regno], NULL_RTX, &info);
COMPL_HARD_REG_SET should always overwrite all of call_saved (it is
call_saved = ~call_used_reg_set).
> --- gcc/fixed-value.c (revision 245620)
> +++ gcc/fixed-value.c (working copy)
> @@ -130,8 +130,8 @@ fixed_from_string (FIXED_VALUE_TYPE *f,
> real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
> wide_int w = real_to_integer (&fixed_value, &fail,
> GET_MODE_PRECISION (mode));
> - f->data.low = w.elt (0);
> - f->data.high = w.elt (1);
> + f->data.low = w.ulow ();
> + f->data.high = w.uhigh ();
Is this for the case when the wide_int has only a single uhwi (or more than
two)?
> --- gcc/ipa-cp.c (revision 245620)
> +++ gcc/ipa-cp.c (working copy)
> @@ -4959,7 +4959,6 @@ ipcp_store_vr_results (void)
> {
> vr.known = false;
> vr.type = VR_VARYING;
> - vr.min = vr.max = wi::zero (INT_TYPE_SIZE);
> }
> ts->m_vr->quick_push (vr);
> }
It is strange to see removing initialization of something as a work-around
to uninitialized warning. Is that because of the vr.min = vr.max assignment
and that wi::zero doesn't initialize everything?
Jakub