On Thu, 27 Apr 2017, Bin.Cheng wrote:
> On Thu, Apr 27, 2017 at 10:25 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;
> > + }
> But it returns chrec_dont_know in the case it didn't if LOOP_CLOSED_SSA?
if ! LOOP_CLOSED_SSA, if in LOOP_CLOSED_SSA it continues to ICE.
Richard.
> Thanks,
> bin
> >
> > 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;
> > +}
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
