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 <ja...@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
