[Bug tree-optimization/83857] [8 Regression] internal compiler error: in exact_div, at poly-int.h:2139

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83857

--- Comment #6 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Author: rsandifo
Date: Tue Jan 16 15:13:32 2018
New Revision: 256747

URL: https://gcc.gnu.org/viewcvs?rev=256747&root=gcc&view=rev
Log:
Two fixes for live-out SLP inductions (PR 83857)

vect_analyze_loop_operations was calling vectorizable_live_operation
for all live-out phis, which led to a bogus ncopies calculation in
the pure SLP case.  I think v_a_l_o should only be passing phis
that are vectorised using normal loop vectorisation, since
vect_slp_analyze_node_operations handles the SLP side (and knows
the correct slp_index and slp_node arguments to pass in, via
vect_analyze_stmt).

With that fixed we hit an older bug that vectorizable_live_operation
didn't handle live-out SLP inductions.  Fixed by using gimple_phi_result
rather than gimple_get_lhs for phis.

2018-01-16  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
        PR tree-optimization/83857
        * tree-vect-loop.c (vect_analyze_loop_operations): Don't call
        vectorizable_live_operation for pure SLP statements.
        (vectorizable_live_operation): Handle PHIs.

gcc/testsuite/
        PR tree-optimization/83857
        * gcc.dg/vect/pr83857.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/vect/pr83857.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-loop.c