On Wed, 13 Sep 2017, Jakub Jelinek wrote:
> Hi!
>
> The testcase below (and others) still ICEs with my PR81766 fix.
> If there is a cfg cleanup in between ix86_init_pic_reg (during RA)
> and postreload, the label which my fix moved to the right spot is
> turned into NOTE_INSN_DELETED_LABEL note and moved back where it
> originally used to be emitted.
>
> The bug is actually in generic code.
> cselib.c has code to handle LABEL_REF properly during hashing, by not
> hashing the instructions/notes that are operand thereof, but just the
> label number. Postreload though calls cselib_lookup directly on the
> operands of an instruction, and it is very common in many backends to have
> (label_ref (match_operand ...)) in many patterns, and thus cselib
> doesn't use the LABEL_REF handling in that case.
> To avoid crashing postreload.c has:
> /* cselib blows up on CODE_LABELs. Trying to fix that doesn't seem
> right, so avoid the problem here. Likewise if we have a constant
> and the insn pattern doesn't tell us the mode we need. */
> if (LABEL_P (recog_data.operand[i])
> || (CONSTANT_P (recog_data.operand[i])
> && recog_data.operand_mode[i] == VOIDmode))
> continue;
> - we won't look up anything useful for those operands anyway.
> The problem is that a valid LABEL_REF operand doesn't have to be only
> a CODE_LABEL, it can be a NOTE with NOTE_INSN_DELETED_LABEL if all we need
> is the label's address and nothing else.
>
> So, the following patch handles NOTE_INSN_DELETED_LABEL like CODE_LABEL
> in postreload.c.
>
> Once that is done, my earlier PR81766 fix can be effectively reverted
> and instead the CODE_LABEL can be immediately turned into
> NOTE_INSN_DELETED_LABEL, something that a cfgcleanup would do.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
The postreload change is ok.
Thanks,
Richard.
> 2017-09-13 Jakub Jelinek <ja...@redhat.com>
>
> PR target/82145
> * postreload.c (reload_cse_simplify_operands): Skip
> NOTE_INSN_DELETED_LABEL similarly to skipping CODE_LABEL.
> * config/i386/i386.c (ix86_init_large_pic_reg): Revert 2017-09-01
> changes. Turn CODE_LABEL into NOTE_INSN_DELETED_LABEL immediately.
> (ix86_init_pic_reg): Revert 2017-09-01 changes.
>
> * gcc.target/i386/pr82145.c: New test.
>
> --- gcc/config/i386/i386.c.jj 2017-09-08 09:13:59.000000000 +0200
> +++ gcc/config/i386/i386.c 2017-09-11 14:48:50.532094255 +0200
> @@ -8885,7 +8885,7 @@ ix86_use_pseudo_pic_reg (void)
>
> /* Initialize large model PIC register. */
>
> -static rtx_code_label *
> +static void
> ix86_init_large_pic_reg (unsigned int tmp_regno)
> {
> rtx_code_label *label;
> @@ -8902,7 +8902,10 @@ ix86_init_large_pic_reg (unsigned int tm
> emit_insn (gen_set_got_offset_rex64 (tmp_reg, label));
> emit_insn (ix86_gen_add3 (pic_offset_table_rtx,
> pic_offset_table_rtx, tmp_reg));
> - return label;
> + const char *name = LABEL_NAME (label);
> + PUT_CODE (label, NOTE);
> + NOTE_KIND (label) = NOTE_INSN_DELETED_LABEL;
> + NOTE_DELETED_LABEL_NAME (label) = name;
> }
>
> /* Create and initialize PIC register if required. */
> @@ -8911,7 +8914,6 @@ ix86_init_pic_reg (void)
> {
> edge entry_edge;
> rtx_insn *seq;
> - rtx_code_label *label = NULL;
>
> if (!ix86_use_pseudo_pic_reg ())
> return;
> @@ -8921,7 +8923,7 @@ ix86_init_pic_reg (void)
> if (TARGET_64BIT)
> {
> if (ix86_cmodel == CM_LARGE_PIC)
> - label = ix86_init_large_pic_reg (R11_REG);
> + ix86_init_large_pic_reg (R11_REG);
> else
> emit_insn (gen_set_got_rex64 (pic_offset_table_rtx));
> }
> @@ -8945,22 +8947,6 @@ ix86_init_pic_reg (void)
> entry_edge = single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun));
> insert_insn_on_edge (seq, entry_edge);
> commit_one_edge_insertion (entry_edge);
> -
> - if (label)
> - {
> - basic_block bb = BLOCK_FOR_INSN (label);
> - rtx_insn *bb_note = PREV_INSN (label);
> - /* If the note preceding the label starts a basic block, and the
> - label is a member of the same basic block, interchange the two. */
> - if (bb_note != NULL_RTX
> - && NOTE_INSN_BASIC_BLOCK_P (bb_note)
> - && bb != NULL
> - && bb == BLOCK_FOR_INSN (bb_note))
> - {
> - reorder_insns_nobb (bb_note, bb_note, label);
> - BB_HEAD (bb) = label;
> - }
> - }
> }
>
> /* Initialize a variable CUM of type CUMULATIVE_ARGS
> --- gcc/postreload.c.jj 2017-09-08 09:13:54.000000000 +0200
> +++ gcc/postreload.c 2017-09-11 14:49:04.977945563 +0200
> @@ -409,9 +409,12 @@ reload_cse_simplify_operands (rtx_insn *
> CLEAR_HARD_REG_SET (equiv_regs[i]);
>
> /* cselib blows up on CODE_LABELs. Trying to fix that doesn't seem
> - right, so avoid the problem here. Likewise if we have a constant
> - and the insn pattern doesn't tell us the mode we need. */
> + right, so avoid the problem here. Similarly NOTE_INSN_DELETED_LABEL.
> + Likewise if we have a constant and the insn pattern doesn't tell us
> + the mode we need. */
> if (LABEL_P (recog_data.operand[i])
> + || (NOTE_P (recog_data.operand[i])
> + && NOTE_KIND (recog_data.operand[i]) == NOTE_INSN_DELETED_LABEL)
> || (CONSTANT_P (recog_data.operand[i])
> && recog_data.operand_mode[i] == VOIDmode))
> continue;
> --- gcc/testsuite/gcc.target/i386/pr82145.c.jj 2017-09-11
> 14:46:08.612760951 +0200
> +++ gcc/testsuite/gcc.target/i386/pr82145.c 2017-09-11 14:47:22.090004622
> +0200
> @@ -0,0 +1,12 @@
> +/* PR target/82145 */
> +/* { dg-do compile { target { pie && lp64 } } } */
> +/* { dg-options "-O2 -fpie -mcmodel=large -march=haswell" } */
> +
> +int l;
> +
> +int
> +main ()
> +{
> + l++;
> + return 0;
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
