The patch looks good to me.
Thanks,
Sebastian
On Thu, Apr 27, 2017 at 4:25 AM, Richard Biener <rguent...@suse.de> wrote:
>
> SCEV analysis requires us to be in loop-closed SSA form to be able
> to compute overall effects of inner loops when required. Unfortunately
> we have too many places it is used where we are not in loop-closed SSA
> form. The following patch makes us more conservative in two places
> where we previously ICEd.
>
> I'm not 100% sure we'll get away w/ not being in loop-closed SSA form
> (code correctness wise) but unless we get a testcase showing this the
> following is a sane approach (esp. on release branches).
>
> Bootstrap and regtest in progress on x86_64-unknown-linux-gnu.
>
> Richard.
>
> 2017-04-27 Richard Biener <rguent...@suse.de>
>
> PR middle-end/80539
> * tree-chrec.c (chrec_fold_plus_poly_poly): Deal with not
> being in loop-closed SSA form conservatively.
> (chrec_fold_multiply_poly_poly): Likewise.
>
> * gcc.dg/torture/pr80539.c: New testcase.
>
> Index: gcc/tree-chrec.c
> ===================================================================
> --- gcc/tree-chrec.c (revision 247293)
> +++ gcc/tree-chrec.c (working copy)
> @@ -149,7 +149,12 @@ chrec_fold_plus_poly_poly (enum tree_cod
>
> /* This function should never be called for chrecs of loops that
> do not belong to the same loop nest. */
> - gcc_assert (loop0 == loop1);
> + if (loop0 != loop1)
> + {
> + /* It still can happen if we are not in loop-closed SSA form. */
> + gcc_assert (! loops_state_satisfies_p (LOOP_CLOSED_SSA));
> + return chrec_dont_know;
> + }
>
> if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
> {
> @@ -211,7 +216,12 @@ chrec_fold_multiply_poly_poly (tree type
> chrec_fold_multiply (type, CHREC_LEFT (poly0), poly1),
> CHREC_RIGHT (poly0));
>
> - gcc_assert (loop0 == loop1);
> + if (loop0 != loop1)
> + {
> + /* It still can happen if we are not in loop-closed SSA form. */
> + gcc_assert (! loops_state_satisfies_p (LOOP_CLOSED_SSA));
> + return chrec_dont_know;
> + }
>
> /* poly0 and poly1 are two polynomials in the same variable,
> {a, +, b}_x * {c, +, d}_x -> {a*c, +, a*d + b*c + b*d, +, 2*b*d}_x.
> */
> Index: gcc/testsuite/gcc.dg/torture/pr80539.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/torture/pr80539.c (nonexistent)
> +++ gcc/testsuite/gcc.dg/torture/pr80539.c (working copy)
> @@ -0,0 +1,22 @@
> +/* { dg-do compile } */
> +
> +signed char a, b;
> +void fn1()
> +{
> + signed char c, e;
> + short d;
> + if (0) {
> + for (; d;) {
> +l1:
> + for (c = 7; a; c++)
> + ;
> + e = 6;
> + for (; b; e++)
> + ;
> + }
> + c -= e;
> + }
> + if (d == 7)
> + goto l1;
> + a = c;
> +}
