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Re: [PATCH,PR50763] Follow-up patch to fix i686 bootstrap failure
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Tom de Vries <Tom_deVries at mentor dot com>
- Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Wed, 26 Oct 2011 10:38:17 +0200
- Subject: Re: [PATCH,PR50763] Follow-up patch to fix i686 bootstrap failure
- References: <4EA6A861.9090107@mentor.com>
On Tue, Oct 25, 2011 at 2:15 PM, Tom de Vries <Tom_deVries@mentor.com> wrote:
> Richard,
>
> I have a patch for the i686 bootstrap problem reported in PR50763 comment 10.
>
> pr50763-2.c looks like this before tail_merge_optimize:
> ...
> std_canonical_va_list_type (union tree_node * typeD.1608)
> {
> ?_BoolD.1576 pretmp.6D.2739;
> ?union tree_node * pretmp.5D.2738;
> ?_BoolD.1576 pretmp.4D.2737;
> ?union tree_node * pretmp.3D.2736;
> ?intD.6 D.2734;
> ?_BoolD.1576 D.2733;
> ?union tree_node * D.2725;
> ?intD.6 D.2722;
> ?intD.6 D.2717;
>
> ?# BLOCK 2 freq:10000
> ?# PRED: ENTRY [100.0%] ?(fallthru,exec)
> ?# VUSE <.MEMD.2730_12(D)>
> ?D.2717_4 = typeD.1608_3(D)->baseD.1605.codeD.1597;
> ?if (D.2717_4 != 0)
> ? ?goto <bb 3>;
> ?else
> ? ?goto <bb 4>;
> ?# SUCC: 3 [50.0%] ?(true,exec) 4 [50.0%] ?(false,exec)
>
> ?# BLOCK 3 freq:5000
> ?# PRED: 2 [50.0%] ?(true,exec)
> ?# VUSE <.MEMD.2730_12(D)>
> ?# PT = anything
> ?typeD.1608_5 = typeD.1608_3(D)->typedD.1606.typeD.1600;
> ?goto <bb 6>;
> ?# SUCC: 6 [100.0%] ?(fallthru,exec)
>
> ?# BLOCK 4 freq:5000
> ?# PRED: 2 [50.0%] ?(false,exec)
> ?# VUSE <.MEMD.2730_12(D)>
> ?# PT = anything
> ?typeD.1608_6 = typeD.1608_3(D)->typedD.1606.typeD.1600;
> ?# VUSE <.MEMD.2730_12(D)>
> ?D.2722_7 = typeD.1608_6->baseD.1605.codeD.1597;
> ?if (D.2722_7 != 0)
> ? ?goto <bb 5>;
> ?else
> ? ?goto <bb 7>;
> ?# SUCC: 5 [50.0%] ?(true,exec) 7 [50.0%] ?(false,exec)
>
> ?# BLOCK 7 freq:2500
> ?# PRED: 4 [50.0%] ?(false,exec)
> ?goto <bb 6>;
> ?# SUCC: 6 [100.0%] ?(fallthru)
>
> ?# BLOCK 5 freq:2500
> ?# PRED: 4 [50.0%] ?(true,exec)
> ?# SUCC: 6 [100.0%] ?(fallthru,exec)
>
> ?# BLOCK 6 freq:10000
> ?# PRED: 3 [100.0%] ?(fallthru,exec) 7 [100.0%] ?(fallthru) 5 [100.0%]
> (fallthru,exec)
> ?# PT = anything
>
> ?# typeD.1608_1 = PHI <typeD.1608_5(3), typeD.1608_3(D)(7), typeD.1608_6(5)>
> ?# VUSE <.MEMD.2730_12(D)>
> ?# PT = anything
> ?D.2725_9 = typeD.1608_1->type_commonD.1607.main_variantD.1604;
> ?D.2733_15 = D.2725_9 != 0B;
> ?D.2734_14 = (intD.6) D.2733_15;
> ?# VUSE <.MEMD.2730_12(D)>
> ?return D.2734_14;
> ?# SUCC: EXIT [100.0%]
>
> }
> ...
>
> tail_merge_optimize discovers that block 3 and 5 are identical, and removes block 5.
> In replace_block_by, we end up with phi_vuse1 == NULL_TREE and
> phi_vuse2 == .MEMD.2730_12(D).
>
> After the original fix to PR50763, this forces us to update the vuses, while
> that is not necessary.
>
> Attached patch fixes this problem by determining more precisely when the vuses
> need to be updated.
>
> bootstrapped and reg-tested on x86_64 and i686.
>
> OK for trunk?
Ok.
Thanks,
Richard.
> Thanks,
> - Tom
>
> 2011-10-25 ?Tom de Vries ?<tom@codesourcery.com>
>
> ? ? ? ?PR tree-optimization/50763
> ? ? ? ?* tree-ssa-tail-merge.c (replace_block_by): Update vops if phi_vuse1 or
> ? ? ? ?phi_vuse2 is NULL_TREE only if bb1 dominates or is dominated by bb2.
>
> ? ? ? ?* gcc.dg/pr50763-2.c: New test.
>