On 15/03/2024 07:35, Richard Biener wrote:
On Fri, Mar 15, 2024 at 4:35 AM Hongtao Liu <crazy...@gmail.com> wrote:
On Thu, Mar 14, 2024 at 11:42 PM Andrew Stubbs <a...@baylibre.com> wrote:
Don't enable excess lanes when inverting vector bit-masks smaller than the
integer mode. This is yet another case of wrong-code due to mishandling
of oversized bitmasks.
This issue shows up in vect/tsvc/vect-tsvc-s278.c and
vect/tsvc/vect-tsvc-s279.c if I set the preferred vector size to V32
(down from V64) on amdgcn.
OK for mainline?
Andrew
gcc/ChangeLog:
* expr.cc (expand_expr_real_2): Use xor to invert vector masks.
---
gcc/expr.cc | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/gcc/expr.cc b/gcc/expr.cc
index 403eeaa108e4..3540327d879e 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -10497,6 +10497,17 @@ expand_expr_real_2 (sepops ops, rtx target,
machine_mode tmode,
immed_wide_int_const (mask, int_mode),
target, 1, OPTAB_LIB_WIDEN);
}
+ /* If it's a vector mask don't enable excess bits. */
+ else if (VECTOR_BOOLEAN_TYPE_P (type)
+ && SCALAR_INT_MODE_P (mode)
+ && maybe_ne (GET_MODE_PRECISION (mode),
+ TYPE_VECTOR_SUBPARTS (type).to_constant ()))
+ {
+ auto nunits = TYPE_VECTOR_SUBPARTS (type).to_constant ();
+ temp = expand_binop (mode, xor_optab, op0,
+ GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
+ target, true, OPTAB_WIDEN);
+ }
Not review, just curious, should the issue be fixed by the commit in PR113576.
Also wonder besides cbranch, excess land bits also matter?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113576#c35
Yes, you patch BIT_NOT but we decided to patch final compares. Is it that
we need to fixup every mask use in a .COND_* expansion as well? If so
we should do it there.
I thought that the "not" to "xor" change was nice and there was already
code there for fixing bitfields, but OK, I take your point.
The .COND_* statements are handled as internal function calls that are
expanded directly via the optab with no special cases for different call
types. This is because the "expand_cond_*_optab_fn" functions just map
straight to "expand_direct_optab_fn".... would that be the right place
to insert a special case handler to insert "and" operations?
Andrew
