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Re: [PATCH] Fix PR56131 - gcc.dg/pr56035.c ICEs gcc on sparc-linux
- From: Tom de Vries <Tom_deVries at mentor dot com>
- To: Eric Botcazou <ebotcazou at adacore dot com>
- Cc: <gcc-patches at gcc dot gnu dot org>, Mikael Pettersson <mikpe at it dot uu dot se>
- Date: Tue, 5 Feb 2013 10:41:51 +0100
- Subject: Re: [PATCH] Fix PR56131 - gcc.dg/pr56035.c ICEs gcc on sparc-linux
- References: <510FF01D.email@example.com> <1551618.pBYOJKzDYv@polaris>
thanks for the review.
On 05/02/13 10:02, Eric Botcazou wrote:
>> The problem is that in delete_insn, while deleting an undeletable label (in
>> other words, transforming a label into a INSN_NOTE_DELETED_LABEL):
>> - we try to find the bb of a NOTE_INSN_BASIC_BLOCK following the label using
>> BLOCK_FOR_INSN (which is NULL) instead of NOTE_BASIC_BLOCK (which is not
>> NULL), and
>> - we don't handle the case that we find a NULL pointer for that bb
> Can the NOTE_BASIC_BLOCK of a NOTE_INSN_BASIC_BLOCK really be NULL?
I don't know, I was just trying to do defensive programming.
>> This comment in insn-notes.def tells us that the bb info could be in either
>> of the two:
>> /* Record the struct for the following basic block. Uses
>> NOTE_BASIC_BLOCK. FIXME: Redundant with the basic block pointer
>> now included in every insn. */
>> INSN_NOTE (BASIC_BLOCK)
>> The patch fixes the problems by:
>> - using NOTE_BASIC_BLOCK to find the bb of NOTE_INSN_BASIC_BLOCK, and
>> - explicitly handling the cases that the bb of either the label or the note
>> is NULL.
> I don't think that we need to handle the very last case.
>> 2013-02-04 Tom de Vries <firstname.lastname@example.org>
>> PR rtl-optimization/56131
>> * cfgrtl.c (delete_insn): Use NOTE_BASIC_BLOCK instead of BLOCK_FOR_INSN
>> to get the bb of a NOTE_INSN_BASIC_BLOCK. Handle the case that the bb
>> of the label is NULL. Add comment.
> OK on principle, but remove the handling of the NULL NOTE_BASIC_BLOCK and keep
> everything in a single condition.
I've adopted the patch according to your comments, rebuild sparc-linux cc1 and
tested that the ICE does not occur.
I'll bootstrap and retest on x86_64 and check in attached patch.
--- gcc/cfgrtl.c (revision 195747)
+++ gcc/cfgrtl.c (working copy)
@@ -135,7 +135,7 @@ delete_insn (rtx insn)
if (! can_delete_label_p (insn))
const char *name = LABEL_NAME (insn);
- basic_block bb = BLOCK_FOR_INSN (insn);
+ basic_block bb, label_bb = BLOCK_FOR_INSN (insn);
rtx bb_note = NEXT_INSN (insn);
really_delete = false;
@@ -143,10 +143,16 @@ delete_insn (rtx insn)
NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL;
NOTE_DELETED_LABEL_NAME (insn) = name;
- if (bb_note != NULL_RTX && NOTE_INSN_BASIC_BLOCK_P (bb_note)
- && BLOCK_FOR_INSN (bb_note) == bb)
+ /* If the note following the label starts a basic block, and the
+ label is a member of the same basic block, interchange the two.
+ If the label is not marked with a bb, assume it's the same bb. */
+ if (bb_note != NULL_RTX
+ && NOTE_INSN_BASIC_BLOCK_P (bb_note)
+ && (label_bb == NOTE_BASIC_BLOCK (bb_note)
+ || label_bb == NULL))
reorder_insns_nobb (insn, insn, bb_note);
+ bb = NOTE_BASIC_BLOCK (bb_note);
BB_HEAD (bb) = bb_note;
if (BB_END (bb) == bb_note)
BB_END (bb) = insn;