[PR50763] Follow-up patch to fix i686 bootstrap failure

On 11/02/2011 07:02 PM, Tom de Vries wrote:
> On 10/26/2011 10:38 AM, Richard Guenther wrote:
>> 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.
>>
> 
> Committed additional testcase from duplicate PR50854.
> 

Committed 2 additional test-cases.

Thanks,
- Tom

2011-11-04  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/50763
	* g++.dg/pr50763-4.C: New test.
	* gcc.dg/pr50763-5.c: New test.