On Tue, 7 Apr 2015, Jakub Jelinek wrote:
> Hi!
>
> gen_rtx_SUBREG/gen_lowpart_SUBREG ICE when trying to create a subreg
> the backend doesn't like, lowpart_subreg returns NULL. But, for debug info
> purposes, all lowpart subregs are valid, a subreg in the debug insns or
> var-tracking notes is simply a mode punning construct, and even when the
> backend doesn't have any instruction to perform such operation, the debugger
> can always do the punning.
>
> var-tracking.c already has code to emit gen_rtx_raw_SUBREG if everything
> else fails, the following patch adjusts valtrack.c to do the same thing.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2015-04-07 Jakub Jelinek <ja...@redhat.com>
>
> PR debug/65678
> * valtrack.c (debug_lowpart_subreg): New function.
> (dead_debug_insert_temp): Use it.
>
> * g++.dg/debug/pr65678.C: New test.
>
> --- gcc/valtrack.c.jj 2015-01-05 13:07:14.000000000 +0100
> +++ gcc/valtrack.c 2015-04-07 11:10:36.045912355 +0200
> @@ -534,6 +534,22 @@ dead_debug_add (struct dead_debug_local
> bitmap_set_bit (debug->used, uregno);
> }
>
> +/* Like lowpart_subreg, but if a subreg is not valid for machine, force
> + it anyway - for use in debug insns. */
> +
> +static rtx
> +debug_lowpart_subreg (machine_mode outer_mode, rtx expr,
> + machine_mode inner_mode)
> +{
> + if (inner_mode == VOIDmode)
> + inner_mode = GET_MODE (expr);
> + int offset = subreg_lowpart_offset (outer_mode, inner_mode);
> + rtx ret = simplify_gen_subreg (outer_mode, expr, inner_mode, offset);
> + if (ret)
> + return ret;
> + return gen_rtx_raw_SUBREG (outer_mode, expr, offset);
> +}
> +
> /* If UREGNO is referenced by any entry in DEBUG, emit a debug insn
> before or after INSN (depending on WHERE), that binds a (possibly
> global) debug temp to the widest-mode use of UREGNO, if WHERE is
> @@ -662,9 +678,9 @@ dead_debug_insert_temp (struct dead_debu
> /* Ok, it's the same (hardware) REG, but with a different
> mode, so SUBREG it. */
> else
> - breg = lowpart_subreg (GET_MODE (reg),
> - cleanup_auto_inc_dec (src, VOIDmode),
> - GET_MODE (dest));
> + breg = debug_lowpart_subreg (GET_MODE (reg),
> + cleanup_auto_inc_dec (src, VOIDmode),
> + GET_MODE (dest));
> }
> else if (GET_CODE (dest) == SUBREG)
> {
> @@ -684,9 +700,9 @@ dead_debug_insert_temp (struct dead_debu
> breg = NULL;
> /* Yay, we can use SRC, just adjust its mode. */
> else
> - breg = lowpart_subreg (GET_MODE (reg),
> - cleanup_auto_inc_dec (src, VOIDmode),
> - GET_MODE (dest));
> + breg = debug_lowpart_subreg (GET_MODE (reg),
> + cleanup_auto_inc_dec (src, VOIDmode),
> + GET_MODE (dest));
> }
> /* Oh well, we're out of luck. */
> else
> @@ -740,7 +756,8 @@ dead_debug_insert_temp (struct dead_debu
> *DF_REF_REAL_LOC (cur->use) = dval;
> else
> *DF_REF_REAL_LOC (cur->use)
> - = gen_lowpart_SUBREG (GET_MODE (*DF_REF_REAL_LOC (cur->use)), dval);
> + = debug_lowpart_subreg (GET_MODE (*DF_REF_REAL_LOC (cur->use)), dval,
> + GET_MODE (dval));
> /* ??? Should we simplify subreg of subreg? */
> bitmap_set_bit (debug->to_rescan, INSN_UID (DF_REF_INSN (cur->use)));
> uses = cur->next;
> --- gcc/testsuite/g++.dg/debug/pr65678.C.jj 2015-04-07 11:18:51.701891845
> +0200
> +++ gcc/testsuite/g++.dg/debug/pr65678.C 2015-04-07 11:19:50.285943861
> +0200
> @@ -0,0 +1,35 @@
> +// PR debug/65678
> +// { dg-do compile }
> +
> +long long v;
> +
> +static int
> +bar (double x)
> +{
> +#if __SIZEOF_DOUBLE__ == __SIZEOF_LONG_LONG__
> + __builtin_memmove (&v, &x, sizeof v);
> +#else
> + (void) x;
> + v = 0;
> +#endif
> + return v;
> +}
> +
> +struct A
> +{
> + A (double x) : a (bar (x)) {}
> + int m1 ();
> + int m2 () { int b = a; return b; }
> + int a;
> +};
> +
> +void foo ();
> +
> +void
> +baz (double x)
> +{
> + int c = A (x).m2 ();
> + int d = A (x).m1 ();
> + if (d)
> + foo ();
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Jennifer Guild,
Dilip Upmanyu, Graham Norton HRB 21284 (AG Nuernberg)
