------- Additional Comments From dorit at il dot ibm dot com 2005-07-26 13:59
-------
Subject: Re: [4.1 Regression] wrong code for casts and
scev
Hi Sebastian,
The modifications you suggest will make the tests uninteresting - they were
introduced with unknown loop-bound/offset on purpose. In fact, for most of
these tests there are already versions with explicit constant values for
the loop-bound/offset -
vect-46.c with explicit loop-bound becomes vect-40.c
vect-50.c with explicit loop-bound becomes vect-44.c
vect-52.c with explicit loop-bound becomes vect-48.c
vect-58.c with explicit loop-bound becomes vect-54.c
vect-60.c with explicit loop-bound becomes vect-56.c
vect-77.c and vect-78.c with explicit offset become vect-75.c
and vect-92.c also uses unknown loop-bound on purpose.
Can we change something else in the tests to make the evolution-analyzer
return something saner? by changing types of variables? by using some flag?
(by the way, where does it fail the vectorizer? (what are the last things
that dump details reports?))
dorit
>
> FAIL: gcc.dg/vect/vect-46.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-50.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-50.c scan-tree-dump-times Vectorizing an
> unaligned access 2
> FAIL: gcc.dg/vect/vect-50.c scan-tree-dump-times Alignment of access
> forced using peeling 1
> FAIL: gcc.dg/vect/vect-52.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-52.c scan-tree-dump-times Vectorizing an
> unaligned access 2
> FAIL: gcc.dg/vect/vect-58.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-58.c scan-tree-dump-times Alignment of access
> forced using peeling 1
> FAIL: gcc.dg/vect/vect-60.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-60.c scan-tree-dump-times Vectorizing an
> unaligned access 2
> FAIL: gcc.dg/vect/vect-92.c scan-tree-dump-times vectorized 1 loops 3
> FAIL: gcc.dg/vect/vect-92.c scan-tree-dump-times Alignment of access
> forced using peeling 3
>
> In all these cases, the loop bound is a parameter. If IP-constant
> propagation is not used, chrec_convert has not enough information for
> removing the cast. I propose to modify all these testcases to make
> the loop bound explicit.
>
> FAIL: gcc.dg/vect/vect-77.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-77.c scan-tree-dump-times Vectorizing an
> unaligned access 1
> FAIL: gcc.dg/vect/vect-78.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-78.c scan-tree-dump-times Vectorizing an
> unaligned access 1
>
> For these two regressions, the problem is the same: we end with an
> evolution: ib_16 + (aint *) ((long unsigned int) {off_11, +, 1}_1 * 4)
> in which the casts cannot be removed because the offset is not known,
> and even if the number of iterations is known, chrec_convert cannot
> prove that it does not overflow. I propose to propagate the offset
> by hand, or to wait for ipcp ;-)
>
> FAIL: gcc.dg/vect/vect-87.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-87.c scan-tree-dump-times Alignment of access
> forced using peeling 1
> FAIL: gcc.dg/vect/vect-88.c scan-tree-dump-times vectorized 1 loops 1
> FAIL: gcc.dg/vect/vect-88.c scan-tree-dump-times Alignment of access
> forced using peeling 1
>
> For these two testcases we'll need IP-value range propagation. I
> think that we'll have to modify these testcases by inlining the code.
> Dorit, could you look at vect-{77,78,87,88}.c testcases? Thanks.
>
> * tree-cfg.c (print_succ_bbs): Correctly print successors.
> * tree-chrec.c (chrec_convert): Call scev_probably_wraps_p for
checking
> that the iv does not wrap before converting the iv.
> * tree-ssa-loop-ivcanon.c: Correct typo in comment.
> * tree-ssa-loop-ivopts.c (idx_find_step): Add a fixme note.
> * tree-ssa-loop-niter.c (scev_probably_wraps_p): Check that AT_STMT is
> not null.
> (convert_step): Add a comment.
>
> Index: tree-cfg.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-cfg.c,v
> retrieving revision 2.211
> diff -d -u -p -r2.211 tree-cfg.c
> --- tree-cfg.c 12 Jul 2005 13:20:28 -0000 2.211
> +++ tree-cfg.c 26 Jul 2005 09:59:38 -0000
> @@ -4454,7 +4454,7 @@ static void print_pred_bbs (FILE *, basi
> static void print_succ_bbs (FILE *, basic_block bb);
>
>
> -/* Print the predecessors indexes of edge E on FILE. */
> +/* Print on FILE the indexes for the predecessors of basic_block BB. */
>
> static void
> print_pred_bbs (FILE *file, basic_block bb)
> @@ -4463,11 +4463,11 @@ print_pred_bbs (FILE *file, basic_block
> edge_iterator ei;
>
> FOR_EACH_EDGE (e, ei, bb->preds)
> - fprintf (file, "bb_%d", e->src->index);
> + fprintf (file, "bb_%d ", e->src->index);
> }
>
>
> -/* Print the successors indexes of edge E on FILE. */
> +/* Print on FILE the indexes for the successors of basic_block BB. */
>
> static void
> print_succ_bbs (FILE *file, basic_block bb)
> @@ -4476,7 +4476,7 @@ print_succ_bbs (FILE *file, basic_block
> edge_iterator ei;
>
> FOR_EACH_EDGE (e, ei, bb->succs)
> - fprintf (file, "bb_%d", e->src->index);
> + fprintf (file, "bb_%d ", e->dest->index);
> }
>
>
> Index: tree-chrec.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-chrec.c,v
> retrieving revision 2.22
> diff -d -u -p -r2.22 tree-chrec.c
> --- tree-chrec.c 13 Jul 2005 10:08:36 -0000 2.22
> +++ tree-chrec.c 26 Jul 2005 09:59:38 -0000
> @@ -1110,9 +1110,24 @@ chrec_convert (tree type, tree chrec, tr
>
> if (evolution_function_is_affine_p (chrec))
> {
> - tree step = convert_step
> (current_loops->parray[CHREC_VARIABLE (chrec)],
> - type, CHREC_LEFT (chrec), CHREC_RIGHT (chrec),
> - at_stmt);
> + tree step;
> + bool dummy;
> +
> + /* Avoid conversion of (signed char) {(uchar)1, +, (uchar)1}_x
> + when it is not possible to prove that the scev does not wrap.
> + See PR22236, where a sequence 1, 2, ..., 255 has to be
> + converted to signed char, but this would wrap: 1, 2, ...,
> + 127, -128, ... The result should not be {(schar)1, +,
> + (schar)1}_x, but instead, we should keep the conversion:
> + (schar) {(uchar)1, +, (uchar)1}_x. */
> + if (scev_probably_wraps_p (type, CHREC_LEFT (chrec),
> CHREC_RIGHT (chrec),
> + at_stmt,
> + current_loops->parray[CHREC_VARIABLE (chrec)],
> + &dummy))
> + return fold_convert (type, chrec);
> +
> + step = convert_step (current_loops->parray[CHREC_VARIABLE
> (chrec)], type,
> + CHREC_LEFT (chrec), CHREC_RIGHT (chrec), at_stmt);
> if (!step)
> return fold_convert (type, chrec);
>
> Index: tree-ssa-loop-ivcanon.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-ssa-loop-ivcanon.c,v
> retrieving revision 2.18
> diff -d -u -p -r2.18 tree-ssa-loop-ivcanon.c
> --- tree-ssa-loop-ivcanon.c 21 Jul 2005 07:24:10 -0000 2.18
> +++ tree-ssa-loop-ivcanon.c 26 Jul 2005 09:59:38 -0000
> @@ -252,7 +252,7 @@ try_unroll_loop_completely (struct loops
> }
>
> /* Adds a canonical induction variable to LOOP if suitable. LOOPS
> is the loops
> - tree. CREATE_IV is true if we may create a new iv. UL determines
what
> + tree. CREATE_IV is true if we may create a new iv. UL determines
> which loops we are allowed to completely unroll. If TRY_EVAL is
> true, we try
> to determine the number of iterations of a loop by direct evaluation.
> Returns true if cfg is changed. */
> Index: tree-ssa-loop-ivopts.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-ssa-loop-ivopts.c,v
> retrieving revision 2.85
> diff -d -u -p -r2.85 tree-ssa-loop-ivopts.c
> --- tree-ssa-loop-ivopts.c 21 Jul 2005 07:24:10 -0000 2.85
> +++ tree-ssa-loop-ivopts.c 26 Jul 2005 09:59:38 -0000
> @@ -1443,6 +1443,8 @@ idx_find_step (tree base, tree *idx, voi
> /* The step for pointer arithmetics already is 1 byte. */
> step = build_int_cst (sizetype, 1);
>
> + /* FIXME: convert_step should not be used outside chrec_convert: fix
> + this by calling chrec_convert. */
> iv_step = convert_step (dta->ivopts_data->current_loop,
> sizetype, iv->base, iv->step, dta->stmt);
>
> Index: tree-ssa-loop-niter.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-ssa-loop-niter.c,v
> retrieving revision 2.33
> diff -d -u -p -r2.33 tree-ssa-loop-niter.c
> --- tree-ssa-loop-niter.c 21 Jul 2005 07:24:12 -0000 2.33
> +++ tree-ssa-loop-niter.c 26 Jul 2005 09:59:38 -0000
> @@ -1707,7 +1707,7 @@ scev_probably_wraps_p (tree type, tree b
> i_2 to wrap around, but not i.0_6, because it is of a signed
> type. This causes VRP to erroneously fold the predicate above
> because it thinks that i.0_6 cannot be negative. */
> - if (TREE_CODE (at_stmt) == MODIFY_EXPR)
> + if (at_stmt && TREE_CODE (at_stmt) == MODIFY_EXPR)
> {
> tree rhs = TREE_OPERAND (at_stmt, 1);
> tree outer_t = TREE_TYPE (rhs);
> @@ -1748,7 +1748,8 @@ scev_probably_wraps_p (tree type, tree b
> }
>
> /* Return the conversion to NEW_TYPE of the STEP of an induction
> - variable BASE + STEP * I at AT_STMT. */
> + variable BASE + STEP * I at AT_STMT. When it fails, return
> + NULL_TREE. */
>
> tree
> convert_step (struct loop *loop, tree new_type, tree base, tree step,
> Index: testsuite/gcc.dg/vect/vect-46.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-46.c,v
> retrieving revision 1.7
> diff -d -u -p -r1.7 vect-46.c
> --- testsuite/gcc.dg/vect/vect-46.c 31 Mar 2005 18:34:18 -0000 1.7
> +++ testsuite/gcc.dg/vect/vect-46.c 26 Jul 2005 09:59:52 -0000
> @@ -23,11 +23,11 @@ void bar (afloat *pa, afloat *pb, afloat
>
>
> int
> -main1 (int n , afloat * __restrict__ pa, afloat * __restrict__ pb,
> afloat * __restrict__ pc)
> +main1 (afloat * __restrict__ pa, afloat * __restrict__ pb, afloat *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n; i++)
> + for (i = 0; i < N; i++)
> {
> pa[i] = pb[i] * pc[i];
> }
> @@ -38,14 +38,13 @@ main1 (int n , afloat * __restrict__ pa,
> int main (void)
> {
> int i;
> - int n=N;
> afloat a[N];
> afloat b[N] =
{0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57};
> afloat c[N] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
>
> check_vect ();
>
> - main1 (n,a,b,c);
> + main1 (a,b,c);
> bar (a,b,c);
> return 0;
> }
> Index: testsuite/gcc.dg/vect/vect-50.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-50.c,v
> retrieving revision 1.9
> diff -d -u -p -r1.9 vect-50.c
> --- testsuite/gcc.dg/vect/vect-50.c 31 Mar 2005 18:34:18 -0000 1.9
> +++ testsuite/gcc.dg/vect/vect-50.c 26 Jul 2005 09:59:52 -0000
> @@ -22,11 +22,11 @@ void bar (float *pa, float *pb, float *p
>
>
> int
> -main1 (int n, float * __restrict__ pa, float * __restrict__ pb,
> float * __restrict__ pc)
> +main1 (float * __restrict__ pa, float * __restrict__ pb, float *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n; i++)
> + for (i = 0; i < N; i++)
> {
> pa[i] = pb[i] * pc[i];
> }
> @@ -45,7 +45,7 @@ int main (void)
>
> check_vect ();
>
> - main1 (N,a,b,c);
> + main1 (a,b,c);
> return 0;
> }
>
> Index: testsuite/gcc.dg/vect/vect-52.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-52.c,v
> retrieving revision 1.9
> diff -d -u -p -r1.9 vect-52.c
> --- testsuite/gcc.dg/vect/vect-52.c 31 Mar 2005 18:34:18 -0000 1.9
> +++ testsuite/gcc.dg/vect/vect-52.c 26 Jul 2005 09:59:52 -0000
> @@ -23,11 +23,11 @@ void bar (float *pa, float *pb, float *p
>
>
> int
> -main1 (int n, afloat * __restrict__ pa, float * __restrict__ pb,
> float * __restrict__ pc)
> +main1 (afloat * __restrict__ pa, float * __restrict__ pb, float *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n; i++)
> + for (i = 0; i < N; i++)
> {
> pa[i] = pb[i] * pc[i];
> }
> @@ -46,8 +46,8 @@ int main (void)
>
> check_vect ();
>
> - main1 (N,a,&b[1],c);
> - main1 (N,a,&b[1],&c[1]);
> + main1 (a,&b[1],c);
> + main1 (a,&b[1],&c[1]);
> return 0;
> }
>
> Index: testsuite/gcc.dg/vect/vect-58.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-58.c,v
> retrieving revision 1.10
> diff -d -u -p -r1.10 vect-58.c
> --- testsuite/gcc.dg/vect/vect-58.c 31 Mar 2005 18:34:18 -0000 1.10
> +++ testsuite/gcc.dg/vect/vect-58.c 26 Jul 2005 09:59:52 -0000
> @@ -23,11 +23,11 @@ void bar (afloat *pa, afloat *pb, afloat
>
>
> int
> -main1 (int n , afloat * __restrict__ pa, afloat * __restrict__ pb,
> afloat * __restrict__ pc)
> +main1 (afloat * __restrict__ pa, afloat * __restrict__ pb, afloat *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n/2; i++)
> + for (i = 0; i < N/2; i++)
> {
> pa[i+1] = pb[i+1] * pc[i+1];
> }
> @@ -40,14 +40,13 @@ main1 (int n , afloat * __restrict__ pa,
> int main (void)
> {
> int i;
> - int n=N;
> afloat a[N];
> afloat b[N] =
{0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57};
> afloat c[N] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
>
> check_vect ();
>
> - main1 (n,a,b,c);
> + main1 (a,b,c);
> return 0;
> }
>
> Index: testsuite/gcc.dg/vect/vect-60.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-60.c,v
> retrieving revision 1.9
> diff -d -u -p -r1.9 vect-60.c
> --- testsuite/gcc.dg/vect/vect-60.c 31 Mar 2005 18:34:18 -0000 1.9
> +++ testsuite/gcc.dg/vect/vect-60.c 26 Jul 2005 09:59:52 -0000
> @@ -23,11 +23,11 @@ void bar (afloat *pa, afloat *pb, afloat
>
>
> int
> -main1 (int n , afloat * __restrict__ pa, afloat * __restrict__ pb,
> afloat * __restrict__ pc)
> +main1 (afloat * __restrict__ pa, afloat * __restrict__ pb, afloat *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n/2; i++)
> + for (i = 0; i < N/2; i++)
> {
> pa[i] = pb[i+1] * pc[i+1];
> }
> @@ -40,14 +40,13 @@ main1 (int n , afloat * __restrict__ pa,
> int main (void)
> {
> int i;
> - int n=N;
> afloat a[N];
> afloat b[N] =
{0,3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57};
> afloat c[N] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19};
>
> check_vect ();
>
> - main1 (n,a,b,c);
> + main1 (a,b,c);
> return 0;
> }
>
> Index: testsuite/gcc.dg/vect/vect-77.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-77.c,v
> retrieving revision 1.11
> diff -d -u -p -r1.11 vect-77.c
> --- testsuite/gcc.dg/vect/vect-77.c 7 Jun 2005 19:51:25 -0000 1.11
> +++ testsuite/gcc.dg/vect/vect-77.c 26 Jul 2005 09:59:52 -0000
> @@ -20,7 +20,6 @@ int main1 (aint *ib, int off)
> ia[i] = ib[i+off];
> }
>
> -
> /* check results: */
> for (i = 0; i < N; i++)
> {
> Index: testsuite/gcc.dg/vect/vect-92.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/testsuite/gcc.dg/vect/vect-92.c,v
> retrieving revision 1.4
> diff -d -u -p -r1.4 vect-92.c
> --- testsuite/gcc.dg/vect/vect-92.c 16 Jul 2005 18:56:53 -0000 1.4
> +++ testsuite/gcc.dg/vect/vect-92.c 26 Jul 2005 09:59:52 -0000
> @@ -50,17 +50,17 @@ main2 (afloat * __restrict__ pa, afloat
> }
>
> int
> -main3 (afloat * __restrict__ pa, afloat * __restrict__ pb, afloat *
> __restrict__ pc, int n)
> +main3 (afloat * __restrict__ pa, afloat * __restrict__ pb, afloat *
> __restrict__ pc)
> {
> int i;
>
> - for (i = 0; i < n; i++)
> + for (i = 0; i < N-1; i++)
> {
> pa[i+1] = pb[i+1] * pc[i+1];
> }
>
> /* check results: */
> - for (i = 0; i < n; i++)
> + for (i = 0; i < N-1; i++)
> {
> if (pa[i+1] != (pb[i+1] * pc[i+1]))
> abort ();
> @@ -80,7 +80,7 @@ int main (void)
>
> main1 (a,b,c);
> main2 (a,b,c);
> - main3 (a,b,c,N-1);
> + main3 (a,b,c);
>
> return 0;
> }
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22236
