> On Aug 1, 2017, at 3:46 AM, Richard Biener <richard.guent...@gmail.com> wrote:
>
> On Mon, Jul 31, 2017 at 4:03 PM, Bill Schmidt
> <wschm...@linux.vnet.ibm.com> wrote:
>>
>>> On Jul 31, 2017, at 8:19 AM, Bill Schmidt <wschm...@linux.vnet.ibm.com>
>>> wrote:
>>>
>>> That would certainly be much simpler! I'll regstrap it and test it on the
>>> other
>>> occurrence I've found to be certain.
>>
>> Unfortunately, this fails bootstrap:
>>
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/calls.c: In function 'rtx_def*
>> emit_library_call_value_1(int, rtx, rtx, libcall_type, machine_mode, int,
>> va_list)':
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/calls.c:4362:1: error: definition
>> in block 214 does not dominate use in block 14
>> emit_library_call_value_1 (int retval, rtx orgfun, rtx value,
>> ^~~~~~~~~~~~~~~~~~~~~~~~~
>> for SSA_NAME: slsr_772 in statement:
>> slsr_749 = PHI <_17(26), slsr_772(14), slsr_334(214)>
>> PHI argument
>> slsr_772
>> for PHI node
>> slsr_749 = PHI <_17(26), slsr_772(14), slsr_334(214)>
>> during GIMPLE pass: slsr
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/calls.c:4362:1: internal compiler
>> error: verify_ssa failed
>> 0x11567cf3 verify_ssa(bool, bool)
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/tree-ssa.c:1186
>> 0x10fc3fff execute_function_todo
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/passes.c:1997
>> 0x10fc277f do_per_function
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/passes.c:1655
>> 0x10fc42a3 execute_todo
>> /home/wschmidt/gcc/gcc-mainline-test/gcc/passes.c:2044
>> Please submit a full bug report,
>> with preprocessed source if appropriate.
>> Please include the complete backtrace with any bug report.
>> See <https://gcc.gnu.org/bugs/> for instructions.
>>
>> Not terribly surprising given how sensitive this stuff is. I can look into
>> why
>> this fails, but looks like it can't be quite this simple, sadly.
>
> Intersting ... a dg-torture.exp run was clean for me (all I
> tested...). So yes, can you
> check what fails? Maybe run the testsuite with the stage1 compiler.
Looks like it's the stage1 that doesn't build. I think the difference is
that I was building trunk and you were building 6. I'll try to look into
it later today after I get through some meetings.
Bill
>
> Richard.
>
>> Bill
>>
>>>
>>> -- Bill
>>>
>>>> On Jul 31, 2017, at 4:15 AM, Richard Biener <richard.guent...@gmail.com>
>>>> wrote:
>>>>
>>>> On Sun, Jul 30, 2017 at 8:04 PM, Bill Schmidt
>>>> <wschm...@linux.vnet.ibm.com> wrote:
>>>>> Hi,
>>>>>
>>>>> PR81354 identifies a latent bug that can happen in SLSR since the
>>>>> conditional candidate support was first added. SLSR relies on the
>>>>> address of a GIMPLE PHI remaining constant during the course of the
>>>>> optimization pass, but it needs to split edges. The use of
>>>>> make_single_succ_edge and reinstall_phi_args in gimple_split_edge
>>>>> causes GIMPLE PHI statements to be temporarily expanded to add a
>>>>> predecessor, and then rebuilt to have the original number of
>>>>> predecessors. The expansion usually, if not always, causes the PHI
>>>>> statement to change address. Thus gimple_split_edge needs to be
>>>>> rewritten to perform in-situ replacement of PHI arguments.
>>>>>
>>>>> The required pieces of make_single_succ_edge have been extracted into
>>>>> two places: make_replacement_pred_edge, and some fixup code at the
>>>>> end of gimple_split_edge. The division is necessary because the
>>>>> destination of the original edge must remember its original
>>>>> predecessors for the switch processing in
>>>>> gimple_redirect_edge_and_branch_1 to work properly.
>>>>>
>>>>> The function gimple_redirect_edge_and_branch was factored into two
>>>>> pieces so that most of it can be used by gimple_split_edge without
>>>>> calling ssa_redirect_edge, which also interferes with PHIs. The
>>>>> useful bits of ssa_redirect_edge are factored out into the next three
>>>>> lines of gimple_split_edge.
>>>>>
>>>>> Similarly, redirect_eh_edge had already been similarly factored into
>>>>> redirect_eh_edge_1 and ssa_redirect_edge. I took advantage of that
>>>>> and exposed redirect_eh_edge_1 for use in
>>>>> gimple_redirect_edge_and_branch_1.
>>>>>
>>>>> I've added the test from PR81354 as a torture test, but as we've seen,
>>>>> small changes elsewhere in the optimizer can easily hide the problem.
>>>>>
>>>>> Bootstrapped and tested on powerpc64le-linux-gnu with no regressions.
>>>>> Is this ok for trunk? Eventually this needs to be backported to GCC 5,
>>>>> 6, and 7 if that's acceptable, since PR81354 was observed on
>>>>> gcc-5-branch. I haven't yet prepared the backports.
>>>>
>>>> I don't like make_replacement_pred_edge too much. Wouldn't it work
>>>> to make sure we first shrink and then re-grow like if we simply do the
>>>> redirect_edge_and_branch before the make_single_succ_edge call?
>>>> At least quick testing shows it fixes the testcase on the GCC 6 branch for
>>>> me.
>>>>
>>>> Index: gcc/tree-cfg.c
>>>> ===================================================================
>>>> --- gcc/tree-cfg.c (revision 250732)
>>>> +++ gcc/tree-cfg.c (working copy)
>>>> @@ -2753,12 +2753,16 @@ gimple_split_edge (edge edge_in)
>>>> new_bb = create_empty_bb (after_bb);
>>>> new_bb->frequency = EDGE_FREQUENCY (edge_in);
>>>> new_bb->count = edge_in->count;
>>>> +
>>>> + /* First redirect the existing edge to avoid reallocating
>>>> + PHI nodes in dest. */
>>>> + e = redirect_edge_and_branch (edge_in, new_bb);
>>>> + gcc_assert (e == edge_in);
>>>> +
>>>> new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
>>>> new_edge->probability = REG_BR_PROB_BASE;
>>>> new_edge->count = edge_in->count;
>>>>
>>>> - e = redirect_edge_and_branch (edge_in, new_bb);
>>>> - gcc_assert (e == edge_in);
>>>> reinstall_phi_args (new_edge, e);
>>>>
>>>> return new_bb;
>>>>
>>>> Sorry for misleading you to a complex solution.
>>>>
>>>> Thanks,
>>>> Richard.
>>>>
>>>>> Thanks,
>>>>> Bill
>>>>>
>>>>>
>>>>> [gcc]
>>>>>
>>>>> 2017-07-30 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>>>>>
>>>>> PR tree-optimization/81354
>>>>> * tree-cfg.c (gimple_redirect_edge_and_branch_1): New decl.
>>>>> (reinstall_phi_args): Delete function.
>>>>> (make_replacement_pred_edge): New function.
>>>>> (gimple_split_edge): Rewrite.
>>>>> (gimple_redirect_edge_and_branch_1): New function, factored
>>>>> from...
>>>>> (gimple_redirect_edge_and_branch): ...here.
>>>>> (split_critical_edges): Don't re-split already split edges.
>>>>> * tree-eh.c (redirect_eh_edge_1): Make visible.
>>>>> * tree-eh.h (redirect_eh_edge_1): Likewise.
>>>>>
>>>>> [gcc/testsuite]
>>>>>
>>>>> 2017-07-30 Bill Schmidt <wschm...@linux.vnet.ibm.com>
>>>>>
>>>>> PR tree-optimization/81354
>>>>> * g++.dg/torture/pr81354.C: New file.
>>>>>
>>>>>
>>>>> Index: gcc/testsuite/g++.dg/torture/pr81354.C
>>>>> ===================================================================
>>>>> --- gcc/testsuite/g++.dg/torture/pr81354.C (nonexistent)
>>>>> +++ gcc/testsuite/g++.dg/torture/pr81354.C (working copy)
>>>>> @@ -0,0 +1,24 @@
>>>>> +// PR81354 reported this test as crashing in a limited range of
>>>>> revisions.
>>>>> +// { dg-do compile }
>>>>> +
>>>>> +struct T { double a; double b; };
>>>>> +
>>>>> +void foo(T Ad[], int As[2])
>>>>> +{
>>>>> + int j;
>>>>> + int i;
>>>>> + int Bs[2] = {0,0};
>>>>> + T Bd[16];
>>>>> +
>>>>> + for (j = 0; j < 4; j++) {
>>>>> + for (i = 0; i + 1 <= j + 1; i++) {
>>>>> + Ad[i + As[0] * j] = Bd[i + Bs[0] * j];
>>>>> + }
>>>>> +
>>>>> + i = j + 1; // <- comment out this line and it does not crash
>>>>> + for (; i + 1 < 5; i++) {
>>>>> + Ad[i + As[0] * j].a = 0.0;
>>>>> + Ad[i + As[0] * j].b = 0.0;
>>>>> + }
>>>>> + }
>>>>> +}
>>>>> Index: gcc/tree-cfg.c
>>>>> ===================================================================
>>>>> --- gcc/tree-cfg.c (revision 250721)
>>>>> +++ gcc/tree-cfg.c (working copy)
>>>>> @@ -154,6 +154,7 @@ static void make_gimple_switch_edges (gswitch *, b
>>>>> static bool make_goto_expr_edges (basic_block);
>>>>> static void make_gimple_asm_edges (basic_block);
>>>>> static edge gimple_redirect_edge_and_branch (edge, basic_block);
>>>>> +static edge gimple_redirect_edge_and_branch_1 (edge, basic_block);
>>>>> static edge gimple_try_redirect_by_replacing_jump (edge, basic_block);
>>>>>
>>>>> /* Various helpers. */
>>>>> @@ -2776,35 +2777,6 @@ last_and_only_stmt (basic_block bb)
>>>>> return NULL;
>>>>> }
>>>>>
>>>>> -/* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
>>>>> -
>>>>> -static void
>>>>> -reinstall_phi_args (edge new_edge, edge old_edge)
>>>>> -{
>>>>> - edge_var_map *vm;
>>>>> - int i;
>>>>> - gphi_iterator phis;
>>>>> -
>>>>> - vec<edge_var_map> *v = redirect_edge_var_map_vector (old_edge);
>>>>> - if (!v)
>>>>> - return;
>>>>> -
>>>>> - for (i = 0, phis = gsi_start_phis (new_edge->dest);
>>>>> - v->iterate (i, &vm) && !gsi_end_p (phis);
>>>>> - i++, gsi_next (&phis))
>>>>> - {
>>>>> - gphi *phi = phis.phi ();
>>>>> - tree result = redirect_edge_var_map_result (vm);
>>>>> - tree arg = redirect_edge_var_map_def (vm);
>>>>> -
>>>>> - gcc_assert (result == gimple_phi_result (phi));
>>>>> -
>>>>> - add_phi_arg (phi, arg, new_edge, redirect_edge_var_map_location
>>>>> (vm));
>>>>> - }
>>>>> -
>>>>> - redirect_edge_var_map_clear (old_edge);
>>>>> -}
>>>>> -
>>>>> /* Returns the basic block after which the new basic block created
>>>>> by splitting edge EDGE_IN should be placed. Tries to keep the new block
>>>>> near its "logical" location. This is of most help to humans looking
>>>>> @@ -2825,6 +2797,24 @@ split_edge_bb_loc (edge edge_in)
>>>>> return dest_prev;
>>>>> }
>>>>>
>>>>> +/* Create a single-predecessor edge from SRC to DST, replacing the
>>>>> + predecessor edge E_IN of DST, with flags FLAGS. This is done in
>>>>> + situ so that phis in DST will not get re-allocated. */
>>>>> +
>>>>> +static edge
>>>>> +make_replacement_pred_edge (basic_block src, basic_block dest,
>>>>> + edge e_in, int flags)
>>>>> +{
>>>>> + edge e = ggc_cleared_alloc<edge_def> ();
>>>>> + n_edges_for_fn (cfun)++;
>>>>> + e->src = src;
>>>>> + e->dest = dest;
>>>>> + e->flags = flags;
>>>>> + vec_safe_push (src->succs, e);
>>>>> + e->dest_idx = e_in->dest_idx;
>>>>> + return e;
>>>>> +}
>>>>> +
>>>>> /* Split a (typically critical) edge EDGE_IN. Return the new block.
>>>>> Abort on abnormal edges. */
>>>>>
>>>>> @@ -2832,7 +2822,7 @@ static basic_block
>>>>> gimple_split_edge (edge edge_in)
>>>>> {
>>>>> basic_block new_bb, after_bb, dest;
>>>>> - edge new_edge, e;
>>>>> + edge e, f;
>>>>>
>>>>> /* Abnormal edges cannot be split. */
>>>>> gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
>>>>> @@ -2841,15 +2831,33 @@ gimple_split_edge (edge edge_in)
>>>>>
>>>>> after_bb = split_edge_bb_loc (edge_in);
>>>>>
>>>>> + /* Create a new block, and an edge F from that block to the original
>>>>> + destination. */
>>>>> new_bb = create_empty_bb (after_bb);
>>>>> new_bb->frequency = EDGE_FREQUENCY (edge_in);
>>>>> new_bb->count = edge_in->count;
>>>>> - new_edge = make_single_succ_edge (new_bb, dest, EDGE_FALLTHRU);
>>>>> + f = make_replacement_pred_edge (new_bb, dest, edge_in, EDGE_FALLTHRU);
>>>>>
>>>>> - e = redirect_edge_and_branch (edge_in, new_bb);
>>>>> + /* Redirect the original edge to its new successor. */
>>>>> + e = gimple_redirect_edge_and_branch_1 (edge_in, new_bb);
>>>>> gcc_assert (e == edge_in);
>>>>> - reinstall_phi_args (new_edge, e);
>>>>> + e->dest = new_bb;
>>>>> + vec_safe_push (new_bb->preds, e);
>>>>> + e->dest_idx = 0;
>>>>>
>>>>> + /* Fix up the predecessor edge for DEST to now be F. We can't do
>>>>> + this prior to gimple_redirect_edge_and_branch_1 without raising
>>>>> + havoc in the switch code. */
>>>>> + int idx = -1;
>>>>> + for (unsigned int i = 0; i < EDGE_COUNT (dest->preds); i++)
>>>>> + if (EDGE_PRED (dest, i) == edge_in)
>>>>> + {
>>>>> + idx = i;
>>>>> + break;
>>>>> + }
>>>>> + gcc_assert (idx != -1);
>>>>> + EDGE_PRED (dest, idx) = f;
>>>>> +
>>>>> return new_bb;
>>>>> }
>>>>>
>>>>> @@ -5740,12 +5748,10 @@ gimple_try_redirect_by_replacing_jump (edge e, bas
>>>>> return NULL;
>>>>> }
>>>>>
>>>>> +/* Primary worker for gimple_redirect_edge_and_branch. */
>>>>>
>>>>> -/* Redirect E to DEST. Return NULL on failure. Otherwise, return the
>>>>> - edge representing the redirected branch. */
>>>>> -
>>>>> static edge
>>>>> -gimple_redirect_edge_and_branch (edge e, basic_block dest)
>>>>> +gimple_redirect_edge_and_branch_1 (edge e, basic_block dest)
>>>>> {
>>>>> basic_block bb = e->src;
>>>>> gimple_stmt_iterator gsi;
>>>>> @@ -5759,7 +5765,10 @@ static edge
>>>>> return NULL;
>>>>>
>>>>> if (e->flags & EDGE_EH)
>>>>> - return redirect_eh_edge (e, dest);
>>>>> + {
>>>>> + redirect_eh_edge_1 (e, dest, false);
>>>>> + return e;
>>>>> + }
>>>>>
>>>>> if (e->src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
>>>>> {
>>>>> @@ -5887,9 +5896,19 @@ static edge
>>>>> gcc_assert (e->flags & EDGE_FALLTHRU);
>>>>> break;
>>>>> }
>>>>> + return e;
>>>>> +}
>>>>>
>>>>> - /* Update/insert PHI nodes as necessary. */
>>>>> +/* Redirect E to DEST. Return NULL on failure. Otherwise, return the
>>>>> + edge representing the redirected branch. */
>>>>>
>>>>> +static edge
>>>>> +gimple_redirect_edge_and_branch (edge e, basic_block dest)
>>>>> +{
>>>>> + edge f = gimple_redirect_edge_and_branch_1 (e, dest);
>>>>> + if (f != e)
>>>>> + return f;
>>>>> +
>>>>> /* Now update the edges in the CFG. */
>>>>> e = ssa_redirect_edge (e, dest);
>>>>>
>>>>> @@ -8636,13 +8655,18 @@ split_critical_edges (void)
>>>>> basic_block bb;
>>>>> edge e;
>>>>> edge_iterator ei;
>>>>> + int first_free_block;
>>>>>
>>>>> /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
>>>>> expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
>>>>> mappings around the calls to split_edge. */
>>>>> start_recording_case_labels ();
>>>>> + first_free_block = last_basic_block_for_fn (cfun);
>>>>> FOR_ALL_BB_FN (bb, cfun)
>>>>> {
>>>>> + /* Don't re-split edges we've already split. */
>>>>> + if (bb->index >= first_free_block)
>>>>> + continue;
>>>>> FOR_EACH_EDGE (e, ei, bb->succs)
>>>>> {
>>>>> if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
>>>>> Index: gcc/tree-eh.c
>>>>> ===================================================================
>>>>> --- gcc/tree-eh.c (revision 250721)
>>>>> +++ gcc/tree-eh.c (working copy)
>>>>> @@ -2279,7 +2279,7 @@ make_eh_edges (gimple *stmt)
>>>>> If false, we're being called from generic cfg manipulation code and we
>>>>> should preserve our place within the region tree. */
>>>>>
>>>>> -static void
>>>>> +void
>>>>> redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region)
>>>>> {
>>>>> eh_landing_pad old_lp, new_lp;
>>>>> Index: gcc/tree-eh.h
>>>>> ===================================================================
>>>>> --- gcc/tree-eh.h (revision 250721)
>>>>> +++ gcc/tree-eh.h (working copy)
>>>>> @@ -32,6 +32,7 @@ extern int lookup_stmt_eh_lp (gimple *);
>>>>> extern bool make_eh_dispatch_edges (geh_dispatch *);
>>>>> extern void make_eh_edges (gimple *);
>>>>> extern edge redirect_eh_edge (edge, basic_block);
>>>>> +extern void redirect_eh_edge_1 (edge, basic_block, bool);
>>>>> extern void redirect_eh_dispatch_edge (geh_dispatch *, edge, basic_block);
>>>>> extern bool operation_could_trap_helper_p (enum tree_code, bool, bool,
>>>>> bool,
>>>>> bool, tree, bool *);
