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Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1
- 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, iant at google dot com
- Date: Mon, 4 Apr 2016 15:06:17 +0200
- Subject: Re: [PATCH][GCC 7] Remove broken path in extract_bit_field_1
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot LSU dot 2 dot 11 dot 1604041449590 dot 13384 at t29 dot fhfr dot qr>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Mon, Apr 04, 2016 at 02:56:51PM +0200, Richard Biener wrote:
> The testcase gcc.target/i386/pr37870.c will already ICE with that
> patch, so no additional testcase.
In theory you could validate_subreg first and use that code if validation
went ok, otherwise go through memory.
But I admit I don't have anything in particular in mind where it would
trigger this code and the subreg would successfully validate.
> 2016-04-04 Richard Biener <rguenther@suse.de>
>
> PR middle-end/37870
> * expmed.c (extract_bit_field_1): Remove broken case
> using a wider MODE_INT mode.
>
> Index: gcc/expmed.c
> ===================================================================
> --- gcc/expmed.c (revision 234708)
> +++ gcc/expmed.c (working copy)
> @@ -1647,17 +1647,6 @@ extract_bit_field_1 (rtx str_rtx, unsign
> if (GET_CODE (op0) == SUBREG)
> op0 = force_reg (imode, op0);
> }
> - else if (REG_P (op0))
> - {
> - rtx reg, subreg;
> - imode = smallest_mode_for_size (GET_MODE_BITSIZE (GET_MODE (op0)),
> - MODE_INT);
> - reg = gen_reg_rtx (imode);
> - subreg = gen_lowpart_SUBREG (GET_MODE (op0), reg);
> - emit_move_insn (subreg, op0);
> - op0 = reg;
> - bitnum += SUBREG_BYTE (subreg) * BITS_PER_UNIT;
> - }
> else
> {
> HOST_WIDE_INT size = GET_MODE_SIZE (GET_MODE (op0));
Jakub