tree-optimization/111048 - avoid flawed logic in fold_vec_perm
Checks
Commit Message
The following avoids running into somehow flawed logic in fold_vec_perm
for non-VLA vectors.
Bootstrap & regtest running on x86_64-unknown-linux-gnu.
Richard.
PR tree-optimization/111048
* fold-const.cc (fold_vec_perm_cst): Check for non-VLA
vectors first.
* gcc.dg/torture/pr111048.c: New testcase.
---
gcc/fold-const.cc | 12 ++++++------
gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
2 files changed, 30 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
Comments
Richard Biener <rguenther@suse.de> writes:
> The following avoids running into somehow flawed logic in fold_vec_perm
> for non-VLA vectors.
>
> Bootstrap & regtest running on x86_64-unknown-linux-gnu.
>
> Richard.
>
> PR tree-optimization/111048
> * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
> vectors first.
>
> * gcc.dg/torture/pr111048.c: New testcase.
Please don't do this as a permanent thing. It was a deliberate choice
to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
logic gets more coverage. Like you say, if something is wrong for VLS
then the chances are that it's also wrong for VLA.
Thanks,
Richard
> ---
> gcc/fold-const.cc | 12 ++++++------
> gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
> 2 files changed, 30 insertions(+), 6 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
>
> diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> index 5c51c9d91be..144fd7481b3 100644
> --- a/gcc/fold-const.cc
> +++ b/gcc/fold-const.cc
> @@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> unsigned res_npatterns, res_nelts_per_pattern;
> unsigned HOST_WIDE_INT res_nelts;
>
> + if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> + {
> + res_npatterns = res_nelts;
> + res_nelts_per_pattern = 1;
> + }
> /* (1) If SEL is a suitable mask as determined by
> valid_mask_for_fold_vec_perm_cst_p, then:
> res_npatterns = max of npatterns between ARG0, ARG1, and SEL
> @@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> res_npatterns = nelts in result vector.
> res_nelts_per_pattern = 1.
> This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
> - if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> + else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> {
> res_npatterns
> = std::max (VECTOR_CST_NPATTERNS (arg0),
> @@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
>
> res_nelts = res_npatterns * res_nelts_per_pattern;
> }
> - else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> - {
> - res_npatterns = res_nelts;
> - res_nelts_per_pattern = 1;
> - }
> else
> return NULL_TREE;
>
> diff --git a/gcc/testsuite/gcc.dg/torture/pr111048.c b/gcc/testsuite/gcc.dg/torture/pr111048.c
> new file mode 100644
> index 00000000000..475978aae2b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/torture/pr111048.c
> @@ -0,0 +1,24 @@
> +/* { dg-do run } */
> +/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
> +
> +typedef unsigned char u8;
> +
> +__attribute__((noipa))
> +static void check(const u8 * v) {
> + if (*v != 15) __builtin_trap();
> +}
> +
> +__attribute__((noipa))
> +static void bug(void) {
> + u8 in_lanes[32];
> + for (unsigned i = 0; i < 32; i += 2) {
> + in_lanes[i + 0] = 0;
> + in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
> + }
> +
> + check(&in_lanes[13]);
> + }
> +
> +int main() {
> + bug();
> +}
On Fri, 18 Aug 2023, Richard Sandiford wrote:
> Richard Biener <rguenther@suse.de> writes:
> > The following avoids running into somehow flawed logic in fold_vec_perm
> > for non-VLA vectors.
> >
> > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
> >
> > Richard.
> >
> > PR tree-optimization/111048
> > * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
> > vectors first.
> >
> > * gcc.dg/torture/pr111048.c: New testcase.
>
> Please don't do this as a permanent thing. It was a deliberate choice
> to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
> logic gets more coverage. Like you say, if something is wrong for VLS
> then the chances are that it's also wrong for VLA.
Sure, feel free to undo this change together with the fix for the
VLA case.
Richard.
> Thanks,
> Richard
>
>
> > ---
> > gcc/fold-const.cc | 12 ++++++------
> > gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
> > 2 files changed, 30 insertions(+), 6 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
> >
> > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> > index 5c51c9d91be..144fd7481b3 100644
> > --- a/gcc/fold-const.cc
> > +++ b/gcc/fold-const.cc
> > @@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > unsigned res_npatterns, res_nelts_per_pattern;
> > unsigned HOST_WIDE_INT res_nelts;
> >
> > + if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > + {
> > + res_npatterns = res_nelts;
> > + res_nelts_per_pattern = 1;
> > + }
> > /* (1) If SEL is a suitable mask as determined by
> > valid_mask_for_fold_vec_perm_cst_p, then:
> > res_npatterns = max of npatterns between ARG0, ARG1, and SEL
> > @@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > res_npatterns = nelts in result vector.
> > res_nelts_per_pattern = 1.
> > This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
> > - if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > + else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > {
> > res_npatterns
> > = std::max (VECTOR_CST_NPATTERNS (arg0),
> > @@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> >
> > res_nelts = res_npatterns * res_nelts_per_pattern;
> > }
> > - else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > - {
> > - res_npatterns = res_nelts;
> > - res_nelts_per_pattern = 1;
> > - }
> > else
> > return NULL_TREE;
> >
> > diff --git a/gcc/testsuite/gcc.dg/torture/pr111048.c b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > new file mode 100644
> > index 00000000000..475978aae2b
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > @@ -0,0 +1,24 @@
> > +/* { dg-do run } */
> > +/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
> > +
> > +typedef unsigned char u8;
> > +
> > +__attribute__((noipa))
> > +static void check(const u8 * v) {
> > + if (*v != 15) __builtin_trap();
> > +}
> > +
> > +__attribute__((noipa))
> > +static void bug(void) {
> > + u8 in_lanes[32];
> > + for (unsigned i = 0; i < 32; i += 2) {
> > + in_lanes[i + 0] = 0;
> > + in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
> > + }
> > +
> > + check(&in_lanes[13]);
> > + }
> > +
> > +int main() {
> > + bug();
> > +}
>
On Fri, 18 Aug 2023 at 14:52, Richard Biener <rguenther@suse.de> wrote:
>
> On Fri, 18 Aug 2023, Richard Sandiford wrote:
>
> > Richard Biener <rguenther@suse.de> writes:
> > > The following avoids running into somehow flawed logic in fold_vec_perm
> > > for non-VLA vectors.
> > >
> > > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
> > >
> > > Richard.
> > >
> > > PR tree-optimization/111048
> > > * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
> > > vectors first.
> > >
> > > * gcc.dg/torture/pr111048.c: New testcase.
> >
> > Please don't do this as a permanent thing. It was a deliberate choice
> > to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
> > logic gets more coverage. Like you say, if something is wrong for VLS
> > then the chances are that it's also wrong for VLA.
>
> Sure, feel free to undo this change together with the fix for the
> VLA case.
Hi,
The attached patch reverts the workaround, and fixes the issue.
Bootstrapped+tested on aarch64-linux-gnu with and without SVE, and
x64_64-linux-gnu.
OK to commit ?
Thanks,
Prathamesh
>
> Richard.
>
> > Thanks,
> > Richard
> >
> >
> > > ---
> > > gcc/fold-const.cc | 12 ++++++------
> > > gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
> > > 2 files changed, 30 insertions(+), 6 deletions(-)
> > > create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
> > >
> > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> > > index 5c51c9d91be..144fd7481b3 100644
> > > --- a/gcc/fold-const.cc
> > > +++ b/gcc/fold-const.cc
> > > @@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > unsigned res_npatterns, res_nelts_per_pattern;
> > > unsigned HOST_WIDE_INT res_nelts;
> > >
> > > + if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > + {
> > > + res_npatterns = res_nelts;
> > > + res_nelts_per_pattern = 1;
> > > + }
> > > /* (1) If SEL is a suitable mask as determined by
> > > valid_mask_for_fold_vec_perm_cst_p, then:
> > > res_npatterns = max of npatterns between ARG0, ARG1, and SEL
> > > @@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > res_npatterns = nelts in result vector.
> > > res_nelts_per_pattern = 1.
> > > This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
> > > - if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > + else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > {
> > > res_npatterns
> > > = std::max (VECTOR_CST_NPATTERNS (arg0),
> > > @@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > >
> > > res_nelts = res_npatterns * res_nelts_per_pattern;
> > > }
> > > - else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > - {
> > > - res_npatterns = res_nelts;
> > > - res_nelts_per_pattern = 1;
> > > - }
> > > else
> > > return NULL_TREE;
> > >
> > > diff --git a/gcc/testsuite/gcc.dg/torture/pr111048.c b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > new file mode 100644
> > > index 00000000000..475978aae2b
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > @@ -0,0 +1,24 @@
> > > +/* { dg-do run } */
> > > +/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
> > > +
> > > +typedef unsigned char u8;
> > > +
> > > +__attribute__((noipa))
> > > +static void check(const u8 * v) {
> > > + if (*v != 15) __builtin_trap();
> > > +}
> > > +
> > > +__attribute__((noipa))
> > > +static void bug(void) {
> > > + u8 in_lanes[32];
> > > + for (unsigned i = 0; i < 32; i += 2) {
> > > + in_lanes[i + 0] = 0;
> > > + in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
> > > + }
> > > +
> > > + check(&in_lanes[13]);
> > > + }
> > > +
> > > +int main() {
> > > + bug();
> > > +}
> >
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
PR111048: Set arg_npatterns correctly.
In valid_mask_for_fold_vec_perm_cst we set arg_npatterns always
to VECTOR_CST_NPATTERNS (arg0) because of (q1 & 0) == 0 in
following condition:
/* Ensure that the stepped sequence always selects from the same
input pattern. */
unsigned arg_npatterns
= ((q1 & 0) == 0) ? VECTOR_CST_NPATTERNS (arg0)
: VECTOR_CST_NPATTERNS (arg1);
resulting in wrong code-gen issues.
The patch fixes this by changing the condition to (q1 & 1) == 0.
gcc/ChangeLog:
PR tree-optimization/111048
* fold-const.cc (valid_mask_for_fold_vec_perm_cst_p): Set arg_npatterns
correctly.
(fold_vec_perm_cst): Remove workaround and again call
valid_mask_fold_vec_perm_cst_p for both VLS and VLA vectors.
(test_fold_vec_perm_cst::test_nunits_min_4): Add test-case.
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index 08530b6ae80..fa1d5834bc3 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -10599,7 +10599,7 @@ valid_mask_for_fold_vec_perm_cst_p (tree arg0, tree arg1,
/* Ensure that the stepped sequence always selects from the same
input pattern. */
unsigned arg_npatterns
- = ((q1 & 0) == 0) ? VECTOR_CST_NPATTERNS (arg0)
+ = ((q1 & 1) == 0) ? VECTOR_CST_NPATTERNS (arg0)
: VECTOR_CST_NPATTERNS (arg1);
if (!multiple_p (step, arg_npatterns))
@@ -10625,11 +10625,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
unsigned res_npatterns, res_nelts_per_pattern;
unsigned HOST_WIDE_INT res_nelts;
- if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
- {
- res_npatterns = res_nelts;
- res_nelts_per_pattern = 1;
- }
/* (1) If SEL is a suitable mask as determined by
valid_mask_for_fold_vec_perm_cst_p, then:
res_npatterns = max of npatterns between ARG0, ARG1, and SEL
@@ -10639,7 +10634,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
res_npatterns = nelts in result vector.
res_nelts_per_pattern = 1.
This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
- else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
+ if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
{
res_npatterns
= std::max (VECTOR_CST_NPATTERNS (arg0),
@@ -10653,6 +10648,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
res_nelts = res_npatterns * res_nelts_per_pattern;
}
+ else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
+ {
+ res_npatterns = res_nelts;
+ res_nelts_per_pattern = 1;
+ }
else
return NULL_TREE;
@@ -17518,6 +17518,36 @@ test_nunits_min_4 (machine_mode vmode)
ARG0(1), ARG0(0), ARG0(2) };
validate_res (2, 3, res, expected_res);
}
+
+ /* Case 7: PR111048: Check that we set arg_npatterns correctly,
+ when arg0, arg1 and sel have different number of patterns.
+ arg0 is of shape (1, 1)
+ arg1 is of shape (4, 1)
+ sel is of shape (2, 3) = {1, len, 2, len+1, 3, len+2, ...}
+
+ In this case the pattern: {len, len+1, len+2, ...} chooses arg1.
+ However,
+ step = (len+2) - (len+1) = 1
+ arg_npatterns = VECTOR_CST_NPATTERNS (arg1) = 4
+ Since step is not a multiple of arg_npatterns,
+ valid_mask_for_fold_vec_perm_cst should return false,
+ and thus fold_vec_perm_cst should return NULL_TREE. */
+ {
+ tree arg0 = build_vec_cst_rand (vmode, 1, 1);
+ tree arg1 = build_vec_cst_rand (vmode, 4, 1);
+ poly_uint64 len = TYPE_VECTOR_SUBPARTS (TREE_TYPE (arg0));
+
+ vec_perm_builder builder (len, 2, 3);
+ poly_uint64 mask_elems[] = { 0, len, 1, len + 1, 2, len + 2 };
+ builder_push_elems (builder, mask_elems);
+
+ vec_perm_indices sel (builder, 2, len);
+ const char *reason;
+ tree res = fold_vec_perm_cst (TREE_TYPE (arg0), arg0, arg1, sel, &reason);
+
+ ASSERT_TRUE (res == NULL_TREE);
+ ASSERT_TRUE (!strcmp (reason, "step is not multiple of npatterns"));
+ }
}
}
On Sat, 19 Aug 2023, Prathamesh Kulkarni wrote:
> On Fri, 18 Aug 2023 at 14:52, Richard Biener <rguenther@suse.de> wrote:
> >
> > On Fri, 18 Aug 2023, Richard Sandiford wrote:
> >
> > > Richard Biener <rguenther@suse.de> writes:
> > > > The following avoids running into somehow flawed logic in fold_vec_perm
> > > > for non-VLA vectors.
> > > >
> > > > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
> > > >
> > > > Richard.
> > > >
> > > > PR tree-optimization/111048
> > > > * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
> > > > vectors first.
> > > >
> > > > * gcc.dg/torture/pr111048.c: New testcase.
> > >
> > > Please don't do this as a permanent thing. It was a deliberate choice
> > > to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
> > > logic gets more coverage. Like you say, if something is wrong for VLS
> > > then the chances are that it's also wrong for VLA.
> >
> > Sure, feel free to undo this change together with the fix for the
> > VLA case.
> Hi,
> The attached patch reverts the workaround, and fixes the issue.
> Bootstrapped+tested on aarch64-linux-gnu with and without SVE, and
> x64_64-linux-gnu.
> OK to commit ?
OK.
> Thanks,
> Prathamesh
> >
> > Richard.
> >
> > > Thanks,
> > > Richard
> > >
> > >
> > > > ---
> > > > gcc/fold-const.cc | 12 ++++++------
> > > > gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
> > > > 2 files changed, 30 insertions(+), 6 deletions(-)
> > > > create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
> > > >
> > > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> > > > index 5c51c9d91be..144fd7481b3 100644
> > > > --- a/gcc/fold-const.cc
> > > > +++ b/gcc/fold-const.cc
> > > > @@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > > unsigned res_npatterns, res_nelts_per_pattern;
> > > > unsigned HOST_WIDE_INT res_nelts;
> > > >
> > > > + if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > > + {
> > > > + res_npatterns = res_nelts;
> > > > + res_nelts_per_pattern = 1;
> > > > + }
> > > > /* (1) If SEL is a suitable mask as determined by
> > > > valid_mask_for_fold_vec_perm_cst_p, then:
> > > > res_npatterns = max of npatterns between ARG0, ARG1, and SEL
> > > > @@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > > res_npatterns = nelts in result vector.
> > > > res_nelts_per_pattern = 1.
> > > > This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
> > > > - if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > > + else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > > {
> > > > res_npatterns
> > > > = std::max (VECTOR_CST_NPATTERNS (arg0),
> > > > @@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > >
> > > > res_nelts = res_npatterns * res_nelts_per_pattern;
> > > > }
> > > > - else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > > - {
> > > > - res_npatterns = res_nelts;
> > > > - res_nelts_per_pattern = 1;
> > > > - }
> > > > else
> > > > return NULL_TREE;
> > > >
> > > > diff --git a/gcc/testsuite/gcc.dg/torture/pr111048.c b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > > new file mode 100644
> > > > index 00000000000..475978aae2b
> > > > --- /dev/null
> > > > +++ b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > > @@ -0,0 +1,24 @@
> > > > +/* { dg-do run } */
> > > > +/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
> > > > +
> > > > +typedef unsigned char u8;
> > > > +
> > > > +__attribute__((noipa))
> > > > +static void check(const u8 * v) {
> > > > + if (*v != 15) __builtin_trap();
> > > > +}
> > > > +
> > > > +__attribute__((noipa))
> > > > +static void bug(void) {
> > > > + u8 in_lanes[32];
> > > > + for (unsigned i = 0; i < 32; i += 2) {
> > > > + in_lanes[i + 0] = 0;
> > > > + in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
> > > > + }
> > > > +
> > > > + check(&in_lanes[13]);
> > > > + }
> > > > +
> > > > +int main() {
> > > > + bug();
> > > > +}
> > >
> >
> > --
> > Richard Biener <rguenther@suse.de>
> > SUSE Software Solutions Germany GmbH,
> > Frankenstrasse 146, 90461 Nuernberg, Germany;
> > GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
>
On Mon, 21 Aug 2023 at 12:26, Richard Biener <rguenther@suse.de> wrote:
>
> On Sat, 19 Aug 2023, Prathamesh Kulkarni wrote:
>
> > On Fri, 18 Aug 2023 at 14:52, Richard Biener <rguenther@suse.de> wrote:
> > >
> > > On Fri, 18 Aug 2023, Richard Sandiford wrote:
> > >
> > > > Richard Biener <rguenther@suse.de> writes:
> > > > > The following avoids running into somehow flawed logic in fold_vec_perm
> > > > > for non-VLA vectors.
> > > > >
> > > > > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
> > > > >
> > > > > Richard.
> > > > >
> > > > > PR tree-optimization/111048
> > > > > * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
> > > > > vectors first.
> > > > >
> > > > > * gcc.dg/torture/pr111048.c: New testcase.
> > > >
> > > > Please don't do this as a permanent thing. It was a deliberate choice
> > > > to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
> > > > logic gets more coverage. Like you say, if something is wrong for VLS
> > > > then the chances are that it's also wrong for VLA.
> > >
> > > Sure, feel free to undo this change together with the fix for the
> > > VLA case.
> > Hi,
> > The attached patch reverts the workaround, and fixes the issue.
> > Bootstrapped+tested on aarch64-linux-gnu with and without SVE, and
> > x64_64-linux-gnu.
> > OK to commit ?
>
> OK.
Thanks, committed to trunk in 649388462e9a3c2de0b90ce525de8044704cc521
Thanks,
Prathamesh
>
> > Thanks,
> > Prathamesh
> > >
> > > Richard.
> > >
> > > > Thanks,
> > > > Richard
> > > >
> > > >
> > > > > ---
> > > > > gcc/fold-const.cc | 12 ++++++------
> > > > > gcc/testsuite/gcc.dg/torture/pr111048.c | 24 ++++++++++++++++++++++++
> > > > > 2 files changed, 30 insertions(+), 6 deletions(-)
> > > > > create mode 100644 gcc/testsuite/gcc.dg/torture/pr111048.c
> > > > >
> > > > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
> > > > > index 5c51c9d91be..144fd7481b3 100644
> > > > > --- a/gcc/fold-const.cc
> > > > > +++ b/gcc/fold-const.cc
> > > > > @@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > > > unsigned res_npatterns, res_nelts_per_pattern;
> > > > > unsigned HOST_WIDE_INT res_nelts;
> > > > >
> > > > > + if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > > > + {
> > > > > + res_npatterns = res_nelts;
> > > > > + res_nelts_per_pattern = 1;
> > > > > + }
> > > > > /* (1) If SEL is a suitable mask as determined by
> > > > > valid_mask_for_fold_vec_perm_cst_p, then:
> > > > > res_npatterns = max of npatterns between ARG0, ARG1, and SEL
> > > > > @@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > > > res_npatterns = nelts in result vector.
> > > > > res_nelts_per_pattern = 1.
> > > > > This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
> > > > > - if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > > > + else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
> > > > > {
> > > > > res_npatterns
> > > > > = std::max (VECTOR_CST_NPATTERNS (arg0),
> > > > > @@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
> > > > >
> > > > > res_nelts = res_npatterns * res_nelts_per_pattern;
> > > > > }
> > > > > - else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
> > > > > - {
> > > > > - res_npatterns = res_nelts;
> > > > > - res_nelts_per_pattern = 1;
> > > > > - }
> > > > > else
> > > > > return NULL_TREE;
> > > > >
> > > > > diff --git a/gcc/testsuite/gcc.dg/torture/pr111048.c b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > > > new file mode 100644
> > > > > index 00000000000..475978aae2b
> > > > > --- /dev/null
> > > > > +++ b/gcc/testsuite/gcc.dg/torture/pr111048.c
> > > > > @@ -0,0 +1,24 @@
> > > > > +/* { dg-do run } */
> > > > > +/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
> > > > > +
> > > > > +typedef unsigned char u8;
> > > > > +
> > > > > +__attribute__((noipa))
> > > > > +static void check(const u8 * v) {
> > > > > + if (*v != 15) __builtin_trap();
> > > > > +}
> > > > > +
> > > > > +__attribute__((noipa))
> > > > > +static void bug(void) {
> > > > > + u8 in_lanes[32];
> > > > > + for (unsigned i = 0; i < 32; i += 2) {
> > > > > + in_lanes[i + 0] = 0;
> > > > > + in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
> > > > > + }
> > > > > +
> > > > > + check(&in_lanes[13]);
> > > > > + }
> > > > > +
> > > > > +int main() {
> > > > > + bug();
> > > > > +}
> > > >
> > >
> > > --
> > > Richard Biener <rguenther@suse.de>
> > > SUSE Software Solutions Germany GmbH,
> > > Frankenstrasse 146, 90461 Nuernberg, Germany;
> > > GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
> >
>
> --
> Richard Biener <rguenther@suse.de>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
Prathamesh Kulkarni <prathamesh.kulkarni@linaro.org> writes:
> On Mon, 21 Aug 2023 at 12:26, Richard Biener <rguenther@suse.de> wrote:
>>
>> On Sat, 19 Aug 2023, Prathamesh Kulkarni wrote:
>>
>> > On Fri, 18 Aug 2023 at 14:52, Richard Biener <rguenther@suse.de> wrote:
>> > >
>> > > On Fri, 18 Aug 2023, Richard Sandiford wrote:
>> > >
>> > > > Richard Biener <rguenther@suse.de> writes:
>> > > > > The following avoids running into somehow flawed logic in fold_vec_perm
>> > > > > for non-VLA vectors.
>> > > > >
>> > > > > Bootstrap & regtest running on x86_64-unknown-linux-gnu.
>> > > > >
>> > > > > Richard.
>> > > > >
>> > > > > PR tree-optimization/111048
>> > > > > * fold-const.cc (fold_vec_perm_cst): Check for non-VLA
>> > > > > vectors first.
>> > > > >
>> > > > > * gcc.dg/torture/pr111048.c: New testcase.
>> > > >
>> > > > Please don't do this as a permanent thing. It was a deliberate choice
>> > > > to have the is_constant be the fallback, so that the "generic" (VLA+VLS)
>> > > > logic gets more coverage. Like you say, if something is wrong for VLS
>> > > > then the chances are that it's also wrong for VLA.
>> > >
>> > > Sure, feel free to undo this change together with the fix for the
>> > > VLA case.
>> > Hi,
>> > The attached patch reverts the workaround, and fixes the issue.
>> > Bootstrapped+tested on aarch64-linux-gnu with and without SVE, and
>> > x64_64-linux-gnu.
>> > OK to commit ?
>>
>> OK.
> Thanks, committed to trunk in 649388462e9a3c2de0b90ce525de8044704cc521
Thanks for the patch. Please remember to close the PR too.
Richard
@@ -10625,6 +10625,11 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
unsigned res_npatterns, res_nelts_per_pattern;
unsigned HOST_WIDE_INT res_nelts;
+ if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
+ {
+ res_npatterns = res_nelts;
+ res_nelts_per_pattern = 1;
+ }
/* (1) If SEL is a suitable mask as determined by
valid_mask_for_fold_vec_perm_cst_p, then:
res_npatterns = max of npatterns between ARG0, ARG1, and SEL
@@ -10634,7 +10639,7 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
res_npatterns = nelts in result vector.
res_nelts_per_pattern = 1.
This exception is made so that VLS ARG0, ARG1 and SEL work as before. */
- if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
+ else if (valid_mask_for_fold_vec_perm_cst_p (arg0, arg1, sel, reason))
{
res_npatterns
= std::max (VECTOR_CST_NPATTERNS (arg0),
@@ -10648,11 +10653,6 @@ fold_vec_perm_cst (tree type, tree arg0, tree arg1, const vec_perm_indices &sel,
res_nelts = res_npatterns * res_nelts_per_pattern;
}
- else if (TYPE_VECTOR_SUBPARTS (type).is_constant (&res_nelts))
- {
- res_npatterns = res_nelts;
- res_nelts_per_pattern = 1;
- }
else
return NULL_TREE;
new file mode 100644
@@ -0,0 +1,24 @@
+/* { dg-do run } */
+/* { dg-additional-options "-mavx2" { target avx2_runtime } } */
+
+typedef unsigned char u8;
+
+__attribute__((noipa))
+static void check(const u8 * v) {
+ if (*v != 15) __builtin_trap();
+}
+
+__attribute__((noipa))
+static void bug(void) {
+ u8 in_lanes[32];
+ for (unsigned i = 0; i < 32; i += 2) {
+ in_lanes[i + 0] = 0;
+ in_lanes[i + 1] = ((u8)0xff) >> (i & 7);
+ }
+
+ check(&in_lanes[13]);
+ }
+
+int main() {
+ bug();
+}