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* [gcc r11-9596] veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
@ 2022-02-19 8:02 Jakub Jelinek
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From: Jakub Jelinek @ 2022-02-19 8:02 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:c81d1a061e5cfab6bd276c5be4cd6161b11e6d44
commit r11-9596-gc81d1a061e5cfab6bd276c5be4cd6161b11e6d44
Author: Jakub Jelinek <jakub@redhat.com>
Date: Tue Feb 1 16:02:54 2022 +0100
veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307]
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.
2022-02-01 Jakub Jelinek <jakub@redhat.com>
PR middle-end/104307
* tree-vect-generic.c (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.
(cherry picked from commit e9bf6d6b0e1d67df6dcee042fbe37ab72c3a38d7)
Diff:
---
gcc/testsuite/gcc.target/i386/pr104307.c | 6 +++++
gcc/tree-vect-generic.c | 38 +++++++++++++++++---------------
2 files changed, 26 insertions(+), 18 deletions(-)
diff --git a/gcc/testsuite/gcc.target/i386/pr104307.c b/gcc/testsuite/gcc.target/i386/pr104307.c
new file mode 100644
index 00000000000..1301539851c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr104307.c
@@ -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"
diff --git a/gcc/tree-vect-generic.c b/gcc/tree-vect-generic.c
index 3348545d18b..0828ff97569 100644
--- a/gcc/tree-vect-generic.c
+++ b/gcc/tree-vect-generic.c
@@ -380,29 +380,31 @@ expand_vector_comparison (gimple_stmt_iterator *gsi, tree type, tree op0,
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)
+ {
+ gimple_stmt_iterator it = gsi_for_stmt (use);
+ if (!expand_vector_condition (&it, dce_ssa_names))
+ {
+ vec_cond_expr_only = false;
+ break;
+ }
+ }
+
if (!uses.is_empty () && vec_cond_expr_only)
return NULL_TREE;
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