On Tue, Aug 18, 2015 at 9:49 PM, Marek Polacek <pola...@redhat.com> wrote:
> On Tue, Aug 18, 2015 at 10:45:21AM +0200, Richard Biener wrote:
>> On Mon, Aug 17, 2015 at 7:31 PM, Jeff Law <l...@redhat.com> wrote:
>> > But in walking through all that, I think I've stumbled on a simpler
>> > solution. Specifically do as a little as possible and let the standard
>> > mechanisms clean things up :-)
>> >
>> > 1. Delete the code that removes instructions after the trap.
>> >
>> > 2. Split the block immediately after the trap and remove the edge
>> > from the original block (with the trap) to the new block.
>>
>> cfg-cleanup will do that for you if you have a not returning stmt ending
>> the previous block.
>
> The following patch hopefully does what's oulined above.
> Arguably I should have renamed the insert_trap_and_remove_trailing_statements
> to something more descriptive, e.g. insert_trap_and_split_block. Your
> call.
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
Looks good to me.
Richard.
> 2015-08-18 Marek Polacek <pola...@redhat.com>
>
> PR middle-end/67133
> * gimple-ssa-isolate-paths.c
> (insert_trap_and_remove_trailing_statements): Rename to ...
> (insert_trap): ... this. Don't remove trailing statements; split
> block instead.
> (find_explicit_erroneous_behaviour): Don't remove all outgoing edges.
>
> * g++.dg/torture/pr67133.C: New test.
>
> diff --git gcc/gimple-ssa-isolate-paths.c gcc/gimple-ssa-isolate-paths.c
> index 6f84f85..ca2322d 100644
> --- gcc/gimple-ssa-isolate-paths.c
> +++ gcc/gimple-ssa-isolate-paths.c
> @@ -66,10 +66,10 @@ check_loadstore (gimple stmt, tree op, tree, void *data)
> return false;
> }
>
> -/* Insert a trap after SI and remove SI and all statements after the trap.
> */
> +/* Insert a trap after SI and split the block after the trap. */
>
> static void
> -insert_trap_and_remove_trailing_statements (gimple_stmt_iterator *si_p, tree
> op)
> +insert_trap (gimple_stmt_iterator *si_p, tree op)
> {
> /* We want the NULL pointer dereference to actually occur so that
> code that wishes to catch the signal can do so.
> @@ -115,18 +115,8 @@ insert_trap_and_remove_trailing_statements
> (gimple_stmt_iterator *si_p, tree op)
> else
> gsi_insert_before (si_p, seq, GSI_NEW_STMT);
>
> - /* We must remove statements from the end of the block so that we
> - never reference a released SSA_NAME. */
> - basic_block bb = gimple_bb (gsi_stmt (*si_p));
> - for (gimple_stmt_iterator si = gsi_last_bb (bb);
> - gsi_stmt (si) != gsi_stmt (*si_p);
> - si = gsi_last_bb (bb))
> - {
> - stmt = gsi_stmt (si);
> - unlink_stmt_vdef (stmt);
> - gsi_remove (&si, true);
> - release_defs (stmt);
> - }
> + split_block (gimple_bb (new_stmt), new_stmt);
> + *si_p = gsi_for_stmt (stmt);
> }
>
> /* BB when reached via incoming edge E will exhibit undefined behaviour
> @@ -215,7 +205,7 @@ isolate_path (basic_block bb, basic_block duplicate,
> update_stmt (ret);
> }
> else
> - insert_trap_and_remove_trailing_statements (&si2, op);
> + insert_trap (&si2, op);
> }
>
> return duplicate;
> @@ -422,14 +412,8 @@ find_explicit_erroneous_behaviour (void)
> continue;
> }
>
> - insert_trap_and_remove_trailing_statements (&si,
> - null_pointer_node);
> -
> - /* And finally, remove all outgoing edges from BB. */
> - edge e;
> - for (edge_iterator ei = ei_start (bb->succs);
> - (e = ei_safe_edge (ei)); )
> - remove_edge (e);
> + insert_trap (&si, null_pointer_node);
> + bb = gimple_bb (gsi_stmt (si));
>
> /* Ignore any more operands on this statement and
> continue the statement iterator (which should
> diff --git gcc/testsuite/g++.dg/torture/pr67133.C
> gcc/testsuite/g++.dg/torture/pr67133.C
> index e69de29..0f23572 100644
> --- gcc/testsuite/g++.dg/torture/pr67133.C
> +++ gcc/testsuite/g++.dg/torture/pr67133.C
> @@ -0,0 +1,46 @@
> +// { dg-do compile }
> +// { dg-additional-options "-fisolate-erroneous-paths-attribute" }
> +
> +class A;
> +struct B {
> + typedef A type;
> +};
> +template <typename> struct I : B {};
> +class C {
> +public:
> + C(char *);
> + int size();
> +};
> +template <typename> struct D;
> +template <typename _Tp, typename = D<_Tp>> class F {
> + class G {
> + template <typename> static _Tp *__test();
> + typedef int _Del;
> +
> + public:
> + typedef decltype(__test<_Del>()) type;
> + };
> +
> +public:
> + typename I<_Tp>::type operator*() {
> + typename G::type a = 0;
> + return *a;
> + }
> +};
> +class H {
> + F<A> Out;
> + H();
> +};
> +void fn1(void *, void *, int) __attribute__((__nonnull__));
> +class A {
> + int OutBufEnd, OutBufCur;
> +
> +public:
> + void operator<<(C p1) {
> + int b, c = p1.size();
> + if (OutBufEnd)
> + fn1(&OutBufCur, &b, c);
> + }
> +};
> +char* a;
> +H::H() { *Out << a; }
>
> Marek
