[Bug tree-optimization/83914] [8 Regression] ice in vect_is_simple_use with -O3

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83914

--- Comment #6 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Author: rsandifo
Date: Fri Jan 19 11:57:34 2018
New Revision: 256884

URL: https://gcc.gnu.org/viewcvs?rev=256884&root=gcc&view=rev
Log:
Avoid ICE for nested inductions (PR 83914)

This testcase ICEd because we converted the initial value of an
induction to the vector element type even for nested inductions.
This isn't necessary because the initial expression is vectorised
normally, and it meant that init_expr was no longer the original
statement operand by the time we called vect_get_vec_def_for_operand.

Also, adding the conversion code here made the existing SLP conversion
redundant.

2018-01-19  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
        PR tree-optimization/83914
        * tree-vect-loop.c (vectorizable_induction): Don't convert
        init_expr or apply the peeling adjustment for inductions
        that are nested within the vectorized loop.

gcc/testsuite/
        PR tree-optimization/83914
        * gcc.dg/vect/pr83914.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/vect/pr83914.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/tree-vect-loop.c