* [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
@ 2022-02-01 9:18 Jakub Jelinek
2022-02-01 9:29 ` Richard Biener
0 siblings, 1 reply; 4+ messages in thread
From: Jakub Jelinek @ 2022-02-01 9:18 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
Hi!
The following testcase fails -fcompare-debug, because expand_vector_comparison
since r11-1786-g1ac9258cca8030745d3c0b8f63186f0adf0ebc27 sets
vec_cond_expr_only when it sees some use other than VEC_COND_EXPR that uses
the lhs in its condition.
Obviously we should ignore debug stmts when doing so, e.g. by not pushing
them to uses.
That would be a 2 liner change, but while looking at it, I'm also worried
about VEC_COND_EXPRs that would use the lhs in more than one operand,
like VEC_COND_EXPR <lhs, lhs, something> or VEC_COND_EXPR <lhs, something, lhs>
(sure, they ought to be folded, but what if they weren't). Because if
something like that happens, then FOR_EACH_IMM_USE_FAST would push the same
stmt multiple times and expand_vector_condition can return true even when
it modifies it (for vector bool masking).
And lastly, it seems quite wasteful to safe_push statements that will just
cause vec_cond_expr_only = false; and break; in the second loop, both for
cases like 1000 immediate non-VEC_COND_EXPR uses and for cases like
999 VEC_COND_EXPRs with lhs in cond followed by a single non-VEC_COND_EXPR
use. So this patch only pushes VEC_COND_EXPRs there. As
expand_vector_condition modifies the IL, it checks the condition again as
before.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2022-02-01 Jakub Jelinek <jakub@redhat.com>
PR middle-end/104307
* tree-vect-generic.cc (expand_vector_comparison): Don't push debug
stmts to uses vector, just set vec_cond_expr_only to false for
non-VEC_COND_EXPRs instead of pushing them into uses. Treat
VEC_COND_EXPRs that use lhs not just in rhs1, but rhs2 or rhs3 too
like non-VEC_COND_EXPRs.
* gcc.target/i386/pr104307.c: New test.
--- gcc/tree-vect-generic.cc.jj 2022-01-20 11:30:45.641577244 +0100
+++ gcc/tree-vect-generic.cc 2022-01-31 18:01:29.062568721 +0100
@@ -436,29 +436,43 @@ expand_vector_comparison (gimple_stmt_it
feeding a VEC_COND_EXPR statement. */
auto_vec<gimple *> uses;
FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
- uses.safe_push (USE_STMT (use_p));
-
- for (unsigned i = 0; i < uses.length (); i ++)
{
- gassign *use = dyn_cast<gassign *> (uses[i]);
- if (use != NULL
+ gimple *use = USE_STMT (use_p);
+ if (is_gimple_debug (use))
+ continue;
+ if (is_gimple_assign (use)
&& gimple_assign_rhs_code (use) == VEC_COND_EXPR
- && gimple_assign_rhs1 (use) == lhs)
- {
- gimple_stmt_iterator it = gsi_for_stmt (use);
- if (!expand_vector_condition (&it, dce_ssa_names))
- {
- vec_cond_expr_only = false;
- break;
- }
- }
+ && gimple_assign_rhs1 (use) == lhs
+ && gimple_assign_rhs2 (use) != lhs
+ && gimple_assign_rhs3 (use) != lhs)
+ uses.safe_push (use);
else
- {
- vec_cond_expr_only = false;
- break;
- }
+ vec_cond_expr_only = false;
}
+ if (vec_cond_expr_only)
+ for (gimple *use : uses)
+ {
+ if (is_gimple_assign (use)
+ && gimple_assign_rhs_code (use) == VEC_COND_EXPR
+ && gimple_assign_rhs1 (use) == lhs
+ && gimple_assign_rhs2 (use) != lhs
+ && gimple_assign_rhs3 (use) != lhs)
+ {
+ gimple_stmt_iterator it = gsi_for_stmt (use);
+ if (!expand_vector_condition (&it, dce_ssa_names))
+ {
+ vec_cond_expr_only = false;
+ break;
+ }
+ }
+ else
+ {
+ vec_cond_expr_only = false;
+ break;
+ }
+ }
+
if (!uses.is_empty () && vec_cond_expr_only)
return NULL_TREE;
--- gcc/testsuite/gcc.target/i386/pr104307.c.jj 2022-01-31 17:34:42.163145798 +0100
+++ gcc/testsuite/gcc.target/i386/pr104307.c 2022-01-31 17:35:14.111696698 +0100
@@ -0,0 +1,6 @@
+/* PR middle-end/104307 */
+/* { dg-do compile } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-O2 -mavx512f -fcompare-debug " } */
+
+#include "pr78669.c"
Jakub
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
2022-02-01 9:18 [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307] Jakub Jelinek
@ 2022-02-01 9:29 ` Richard Biener
2022-02-01 9:46 ` Jakub Jelinek
0 siblings, 1 reply; 4+ messages in thread
From: Richard Biener @ 2022-02-01 9:29 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Tue, 1 Feb 2022, Jakub Jelinek wrote:
> Hi!
>
> The following testcase fails -fcompare-debug, because expand_vector_comparison
> since r11-1786-g1ac9258cca8030745d3c0b8f63186f0adf0ebc27 sets
> vec_cond_expr_only when it sees some use other than VEC_COND_EXPR that uses
> the lhs in its condition.
> Obviously we should ignore debug stmts when doing so, e.g. by not pushing
> them to uses.
> That would be a 2 liner change, but while looking at it, I'm also worried
> about VEC_COND_EXPRs that would use the lhs in more than one operand,
> like VEC_COND_EXPR <lhs, lhs, something> or VEC_COND_EXPR <lhs, something, lhs>
> (sure, they ought to be folded, but what if they weren't). Because if
> something like that happens, then FOR_EACH_IMM_USE_FAST would push the same
> stmt multiple times and expand_vector_condition can return true even when
> it modifies it (for vector bool masking).
> And lastly, it seems quite wasteful to safe_push statements that will just
> cause vec_cond_expr_only = false; and break; in the second loop, both for
> cases like 1000 immediate non-VEC_COND_EXPR uses and for cases like
> 999 VEC_COND_EXPRs with lhs in cond followed by a single non-VEC_COND_EXPR
> use. So this patch only pushes VEC_COND_EXPRs there. As
> expand_vector_condition modifies the IL, it checks the condition again as
> before.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
So I think it's all fine besides the handling of VEC_COND_EXPRs where
the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand
your worry here but shouldn't the stmt end up on the vector at least
once? You can use gimple_assign_rhs1_ptr to see whether the
use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you
never push VEC_COND_EXPRs with such double-use it's not necessary
to check again in the second loop?
That said, the other changes look reasonable.
Thanks,
Richard.
> 2022-02-01 Jakub Jelinek <jakub@redhat.com>
>
> PR middle-end/104307
> * tree-vect-generic.cc (expand_vector_comparison): Don't push debug
> stmts to uses vector, just set vec_cond_expr_only to false for
> non-VEC_COND_EXPRs instead of pushing them into uses. Treat
> VEC_COND_EXPRs that use lhs not just in rhs1, but rhs2 or rhs3 too
> like non-VEC_COND_EXPRs.
>
> * gcc.target/i386/pr104307.c: New test.
>
> --- gcc/tree-vect-generic.cc.jj 2022-01-20 11:30:45.641577244 +0100
> +++ gcc/tree-vect-generic.cc 2022-01-31 18:01:29.062568721 +0100
> @@ -436,29 +436,43 @@ expand_vector_comparison (gimple_stmt_it
> feeding a VEC_COND_EXPR statement. */
> auto_vec<gimple *> uses;
> FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
> - uses.safe_push (USE_STMT (use_p));
> -
> - for (unsigned i = 0; i < uses.length (); i ++)
> {
> - gassign *use = dyn_cast<gassign *> (uses[i]);
> - if (use != NULL
> + gimple *use = USE_STMT (use_p);
> + if (is_gimple_debug (use))
> + continue;
> + if (is_gimple_assign (use)
> && gimple_assign_rhs_code (use) == VEC_COND_EXPR
> - && gimple_assign_rhs1 (use) == lhs)
> - {
> - gimple_stmt_iterator it = gsi_for_stmt (use);
> - if (!expand_vector_condition (&it, dce_ssa_names))
> - {
> - vec_cond_expr_only = false;
> - break;
> - }
> - }
> + && gimple_assign_rhs1 (use) == lhs
> + && gimple_assign_rhs2 (use) != lhs
> + && gimple_assign_rhs3 (use) != lhs)
> + uses.safe_push (use);
> else
> - {
> - vec_cond_expr_only = false;
> - break;
> - }
> + vec_cond_expr_only = false;
> }
>
> + if (vec_cond_expr_only)
> + for (gimple *use : uses)
> + {
> + if (is_gimple_assign (use)
> + && gimple_assign_rhs_code (use) == VEC_COND_EXPR
> + && gimple_assign_rhs1 (use) == lhs
> + && gimple_assign_rhs2 (use) != lhs
> + && gimple_assign_rhs3 (use) != lhs)
> + {
> + gimple_stmt_iterator it = gsi_for_stmt (use);
> + if (!expand_vector_condition (&it, dce_ssa_names))
> + {
> + vec_cond_expr_only = false;
> + break;
> + }
> + }
> + else
> + {
> + vec_cond_expr_only = false;
> + break;
> + }
> + }
> +
> if (!uses.is_empty () && vec_cond_expr_only)
> return NULL_TREE;
>
> --- gcc/testsuite/gcc.target/i386/pr104307.c.jj 2022-01-31 17:34:42.163145798 +0100
> +++ gcc/testsuite/gcc.target/i386/pr104307.c 2022-01-31 17:35:14.111696698 +0100
> @@ -0,0 +1,6 @@
> +/* PR middle-end/104307 */
> +/* { dg-do compile } */
> +/* { dg-require-effective-target int128 } */
> +/* { dg-options "-O2 -mavx512f -fcompare-debug " } */
> +
> +#include "pr78669.c"
>
> Jakub
>
>
--
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
2022-02-01 9:29 ` Richard Biener
@ 2022-02-01 9:46 ` Jakub Jelinek
2022-02-01 9:56 ` Richard Biener
0 siblings, 1 reply; 4+ messages in thread
From: Jakub Jelinek @ 2022-02-01 9:46 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
On Tue, Feb 01, 2022 at 10:29:03AM +0100, Richard Biener wrote:
> So I think it's all fine besides the handling of VEC_COND_EXPRs where
> the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand
> your worry here but shouldn't the stmt end up on the vector at least
> once? You can use gimple_assign_rhs1_ptr to see whether the
My worry is that
FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
uses.safe_push (USE_STMT (use_p));
for a stmt with multiple uses of lhs pushes the same
stmt multiple times.
And then
if (a_is_comparison)
a = gimplify_build2 (gsi, code, type, a1, a2);
a1 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a, b);
a2 = gimplify_build1 (gsi, BIT_NOT_EXPR, type, a);
a2 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a2, c);
a = gimplify_build2 (gsi, BIT_IOR_EXPR, type, a1, a2);
gimple_assign_set_rhs_from_tree (gsi, a);
update_stmt (gsi_stmt (*gsi));
will modify it (though the above at least will not remove the
stmt and update it in place I think) and then it won't be
a VEC_COND_EXPR anymore.
To me the non-cond uses in VEC_COND_EXPR conceptually look like
any other unhandled uses that the second loop clears
vec_cond_expr_only on. But I don't have a testcase, dunno if it is even
possible.
> use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you
> never push VEC_COND_EXPRs with such double-use it's not necessary
> to check again in the second loop?
I was just trying to be extra cautious in case expand_vector_comparison
modifies some other stmts, but maybe it is just expand_vector_comparison
in veclower and no other function that modifies anything but the
current stmt (+ pushes some new preparation statements and follow-up
statements).
So perhaps indeed:
+ if (vec_cond_expr_only)
+ for (gimple *use : uses)
+ {
+ gimple_stmt_iterator it = gsi_for_stmt (use);
+ if (!expand_vector_condition (&it, dce_ssa_names))
+ {
+ vec_cond_expr_only = false;
+ break;
+ }
+ }
for the second loop is enough.
But sure, if you prefer all I can do:
FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
- uses.safe_push (USE_STMT (use_p));
+ if (!is_gimple_debug (USE_STMT (use_p)))
+ uses.safe_push (USE_STMT (use_p));
and keep the rest for GCC 13.
Jakub
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
2022-02-01 9:46 ` Jakub Jelinek
@ 2022-02-01 9:56 ` Richard Biener
0 siblings, 0 replies; 4+ messages in thread
From: Richard Biener @ 2022-02-01 9:56 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: gcc-patches
On Tue, 1 Feb 2022, Jakub Jelinek wrote:
> On Tue, Feb 01, 2022 at 10:29:03AM +0100, Richard Biener wrote:
> > So I think it's all fine besides the handling of VEC_COND_EXPRs where
> > the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand
> > your worry here but shouldn't the stmt end up on the vector at least
> > once? You can use gimple_assign_rhs1_ptr to see whether the
>
> My worry is that
> FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
> uses.safe_push (USE_STMT (use_p));
> for a stmt with multiple uses of lhs pushes the same
> stmt multiple times.
> And then
> if (a_is_comparison)
> a = gimplify_build2 (gsi, code, type, a1, a2);
> a1 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a, b);
> a2 = gimplify_build1 (gsi, BIT_NOT_EXPR, type, a);
> a2 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a2, c);
> a = gimplify_build2 (gsi, BIT_IOR_EXPR, type, a1, a2);
> gimple_assign_set_rhs_from_tree (gsi, a);
> update_stmt (gsi_stmt (*gsi));
> will modify it (though the above at least will not remove the
> stmt and update it in place I think) and then it won't be
> a VEC_COND_EXPR anymore.
Ah, OK. Sure, pushing the stmt multiple times looks bogus and indeed
if we see we'll visit it a second time for a rhs{2,3} use there's
no point in pushing it in the first place.
> To me the non-cond uses in VEC_COND_EXPR conceptually look like
> any other unhandled uses that the second loop clears
> vec_cond_expr_only on. But I don't have a testcase, dunno if it is even
> possible.
>
> > use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you
> > never push VEC_COND_EXPRs with such double-use it's not necessary
> > to check again in the second loop?
>
> I was just trying to be extra cautious in case expand_vector_comparison
> modifies some other stmts, but maybe it is just expand_vector_comparison
> in veclower and no other function that modifies anything but the
> current stmt (+ pushes some new preparation statements and follow-up
> statements).
> So perhaps indeed:
> + if (vec_cond_expr_only)
> + for (gimple *use : uses)
> + {
> + gimple_stmt_iterator it = gsi_for_stmt (use);
> + if (!expand_vector_condition (&it, dce_ssa_names))
> + {
> + vec_cond_expr_only = false;
> + break;
> + }
> + }
> for the second loop is enough.
Yes, I think so.
> But sure, if you prefer all I can do:
> FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs)
> - uses.safe_push (USE_STMT (use_p));
> + if (!is_gimple_debug (USE_STMT (use_p)))
> + uses.safe_push (USE_STMT (use_p));
>
> and keep the rest for GCC 13.
No, I think the change is fine with the second loop adjusted.
Thanks,
Richard.
^ permalink raw reply [flat|nested] 4+ messages in thread
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2022-02-01 9:18 [PATCH] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307] Jakub Jelinek
2022-02-01 9:29 ` Richard Biener
2022-02-01 9:46 ` Jakub Jelinek
2022-02-01 9:56 ` Richard Biener
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