[Bug tree-optimization/105769] [11/12/13 Regression] program segmentation fault with -ftree-vectorize and nested lambdas

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105769

--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #9)
> And just statements that refer to those 3 variables that (incorrectly) share
> the stack slot + basic block boundaries.
> grep 'bias\|D.5698\|D.5681\|:' /tmp/00
>   struct struct void D.5698;
>   struct map_t D.5681;
>   struct vec bias;
>   <bb 2> [local count: 1073741829]:
>   _12 = (long unsigned int) &bias;
>   bias ={v} {CLOBBER};
>   __ct_comp  (&D.5698.__est, &D.5682);
>   <bb 3> [local count: 1073741824]:
>   MEM <vector(2) long unsigned int> [(void *)&D.5698 + 32B] = _21;
>   <bb 4> [local count: 1073741824]:
>   __ct_comp  (_14, &D.5698.__est);
>   <bb 5> [local count: 1073741824]:
>   vect__16.52_79 = MEM <vector(2) long unsigned int> [(void *)&D.5698 + 32B];
>   __dt_base  (&MEM[(struct function *)&D.5698].D.5235);
>   D.5698 ={v} {CLOBBER};
>   D.5698 ={v} {CLOBBER(eol)};
>   MEM <char[16]> [(struct _Function_base *)&D.5681] = {};
>   MEM <vector(2) long unsigned int> [(bool (*<T72d>) (union _Any_data &
> {ref-all}, const union _Any_data & {ref-all}, _Manager_operation) *)&D.5681
> + 16B] = _84;
>   <bb 6> [count: 0]:
> <L5>:
>   <bb 7> [count: 0]:
> <L4>:
>   __dt_base  (&MEM[(struct function *)&D.5698].D.5235);
>   D.5698 ={v} {CLOBBER};
>   <bb 8> [local count: 429496]:
>   <bb 9> [local count: 1073312328]:
>   _19 (&D.5683.D.5217._M_functor, &D.5681);
>   <bb 10> [local count: 1073312328]:
>   __dt_base  (&D.5681.D.5223);
>   D.5681 ={v} {CLOBBER};
>   D.5681 ={v} {CLOBBER(eol)};
>   bias ={v} {CLOBBER(eol)};
>   <bb 11> [count: 0]:
> <L0>:
>   __dt_base  (&D.5681.D.5223);
>   D.5681 ={v} {CLOBBER};
>   D.5681 ={v} {CLOBBER(eol)};
>   <bb 12> [count: 0]:
> <L2>:
>   D.5698 ={v} {CLOBBER};
> 
> Now, perhaps the sharing of stack slot between D.5681 and D.5698 is fine,
> seems
> D.5698 is destructed before D.5681 is constructed:
>   D.5698 ={v} {CLOBBER};
>   D.5698 ={v} {CLOBBER(eol)};
>   MEM <char[16]> [(struct _Function_base *)&D.5681] = {};
> and D.5698 is later used just in EH block reachable only from earlier basic
> blocks
> or just as
>   D.5698 ={v} {CLOBBER};
> in the last EH bb.  But the sharing of the stack slot in between bias and
> D.5698 looks wrong.  What can be seen in the IL is:
>   _12 = (long unsigned int) &bias;
> which has been hoisted before the
>   bias ={v} {CLOBBER};
> statement by the slp1 pass.
> From:
> ;;   basic block 2, loop depth 0
> ;;    pred:       ENTRY
>   _3 = operator<< (&cout, "will do (ab)");
>   endl (_3);
>   MEM[(struct vec *)&cov_jn] ={v} {CLOBBER};
>   bias ={v} {CLOBBER};
>   MEM[(struct function *)&D.5682] ={v} {CLOBBER};
>   MEM <char[16]> [(struct _Function_base *)&D.5682] = {};
>   MEM[(struct function *)&D.5682]._M_invoker = _M_invoke;
>   MEM[(struct function *)&D.5682].D.5235._M_manager = _M_manager;
>   __ct_comp  (&D.5698.__est, &D.5682);
> ;;    succ:       5
> ;;                18
> 
> ;;   basic block 5, loop depth 0
> ;;    pred:       2
>   D.5698.__cov = &cov_jn;
>   D.5698.__bias = &bias;
> in dse4 to:
> ;;   basic block 2, loop depth 0
> ;;    pred:       ENTRY
>   _12 = VIEW_CONVERT_EXPR<long unsigned int>(&bias);
>   _15 = VIEW_CONVERT_EXPR<long unsigned int>(&cov_jn);
>   _21 = {_15, _12};
>   _9 = VIEW_CONVERT_EXPR<long unsigned int>(_M_invoke);
>   _10 = VIEW_CONVERT_EXPR<long unsigned int>(_M_manager);
>   _8 = {_10, _9};
>   _3 = operator<< (&cout, "will do (ab)");
>   endl (_3);
>   MEM[(struct vec *)&cov_jn] ={v} {CLOBBER};
>   bias ={v} {CLOBBER};
>   MEM[(struct function *)&D.5682] ={v} {CLOBBER};
>   MEM <char[16]> [(struct _Function_base *)&D.5682] = {};
>   MEM <vector(2) long unsigned int> [(bool (*<T72d>) (union _Any_data &
> {ref-all}, const union _Any_data & {ref-all}, _Manager_operation) *)&D.5682
> + 16B] = _8;
>   __ct_comp  (&D.5698.__est, &D.5682);
> ;;    succ:       5
> ;;                18
>   
> ;;   basic block 5, loop depth 0
> ;;    pred:       2
>   MEM <vector(2) long unsigned int> [(void *)&D.5698 + 32B] = _21;
> in slp1.
> 
> Is that what is incorrect? And we should never hoist taking of addresses
> before a clobber on that var?

I think that's the usual pattern for the two other stack-slot sharing PRs we
have.  The liveness analysis makes wrong assumptions about CLOBBER and CLOBBER
isn't a barrier for address-takens (and we don't have birth CLOBBERs).

But why does -fstack-reuse=none not help?