On Fri, Apr 6, 2012 at 8:30 PM, Ulrich Weigand <uweig...@de.ibm.com> wrote:
> Hello,
>
> PR 52870 is another crash in vectorizer pattern detection that was uncovered
> by Ira's patch to enable patterns for SLP as well.
>
> In this case, the problem is that vect_recog_widen_mult_pattern detects a
> statement as part of a pattern, but that statement is actually outside of
> the basic block SLP is currently working on. This means the statement
> has no stmt_vinfo allocated, and thus SLP crashes later on when operating
> on the statement.
>
> Note that in theory this could already have happened before that latest
> patch, if vect_recog_widen_mult_pattern would have detected a statement
> outside the current *loop*. That is apparently much rarer, though.
>
> The fix is to verify that the statement is actually part of the current
> basic block or loop, as appropriate. That same check is already performed
> in various other pattern detection routines.
>
> Tested on i686-linux and x86_64 with no regressions.
>
> OK for mainline?
Ok.
Thanks,
Richard.
> Bye,
> Ulrich
>
>
>
> ChangeLog:
>
> gcc/
> PR tree-optimization/52870
> * tree-vect-patterns.c (vect_recog_widen_mult_pattern): Verify that
> presumed pattern statement is within the same loop or basic block.
>
> gcc/testsuite/
> PR tree-optimization/52870
> * gcc.dg/vect/pr52870.c: New test.
>
>
> === added file 'gcc/testsuite/gcc.dg/vect/pr52870.c'
> --- gcc/testsuite/gcc.dg/vect/pr52870.c 1970-01-01 00:00:00 +0000
> +++ gcc/testsuite/gcc.dg/vect/pr52870.c 2012-04-04 16:18:08 +0000
> @@ -0,0 +1,17 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O1 -ftree-vectorize" } */
> +
> +long
> +test (int *x)
> +{
> + unsigned long sx, xprec;
> +
> + sx = *x >= 0 ? *x : -*x;
> +
> + xprec = sx * 64;
> +
> + if (sx < 16384)
> + foo (sx);
> +
> + return xprec;
> +}
>
> === modified file 'gcc/tree-vect-patterns.c'
> --- gcc/tree-vect-patterns.c 2012-02-17 16:18:02 +0000
> +++ gcc/tree-vect-patterns.c 2012-04-04 16:18:08 +0000
> @@ -564,6 +564,16 @@
> VEC (tree, heap) *dummy_vec;
> bool op1_ok;
> bool promotion;
> + loop_vec_info loop_vinfo;
> + struct loop *loop = NULL;
> + bb_vec_info bb_vinfo;
> + stmt_vec_info stmt_vinfo;
> +
> + stmt_vinfo = vinfo_for_stmt (last_stmt);
> + loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_vinfo);
> + bb_vinfo = STMT_VINFO_BB_VINFO (stmt_vinfo);
> + if (loop_vinfo)
> + loop = LOOP_VINFO_LOOP (loop_vinfo);
>
> if (!is_gimple_assign (last_stmt))
> return NULL;
> @@ -635,6 +645,11 @@
> || gimple_assign_rhs_code (use_stmt) != NOP_EXPR)
> return NULL;
>
> + if (!gimple_bb (use_stmt)
> + || (loop && !flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
> + || (!loop && gimple_bb (use_stmt) != BB_VINFO_BB (bb_vinfo)))
> + return NULL;
> +
> use_lhs = gimple_assign_lhs (use_stmt);
> use_type = TREE_TYPE (use_lhs);
> if (!INTEGRAL_TYPE_P (use_type)
>
> --
> Dr. Ulrich Weigand
> GNU Toolchain for Linux on System z and Cell BE
> ulrich.weig...@de.ibm.com
>
