On Thu, Mar 21, 2024 at 3:23 PM Andrew Stubbs <a...@baylibre.com> wrote:
>
> My previous patch to fix this problem with xor was rejected because we
> want to fix these issues only at the point of use. That patch produced
> slightly better code, in this example, but this works too....
>
> These patches fix up a failure in testcase vect/tsvc/vect-tsvc-s278.c when
> configured to use V32 instead of V64 (I plan to do this for RDNA devices).
>
> The problem was that a "not" operation on the mask inadvertently enabled
> inactive lanes 31-63 and corrupted the output. The fix is to adjust the mask
> when calling internal functions (in this case COND_MINUS), when doing masked
> loads and stores, and when doing conditional jumps.
>
> OK for mainline?
>
> Andrew
>
> gcc/ChangeLog:
>
> * dojump.cc (do_compare_rtx_and_jump): Clear excess bits in vector
> bitmaps.
> * internal-fn.cc (expand_fn_using_insn): Likewise.
> (add_mask_and_len_args): Likewise.
> ---
> gcc/dojump.cc | 16 ++++++++++++++++
> gcc/internal-fn.cc | 26 ++++++++++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
> diff --git a/gcc/dojump.cc b/gcc/dojump.cc
> index 88600cb42d3..8df86957e83 100644
> --- a/gcc/dojump.cc
> +++ b/gcc/dojump.cc
> @@ -1235,6 +1235,22 @@ do_compare_rtx_and_jump (rtx op0, rtx op1, enum
> rtx_code code, int unsignedp,
> }
> }
>
> + if (val
> + && VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (val))
> + && SCALAR_INT_MODE_P (mode))
> + {
> + auto nunits = TYPE_VECTOR_SUBPARTS (TREE_TYPE (val)).to_constant ();
> + if (maybe_ne (GET_MODE_PRECISION (mode), nunits))
> + {
> + op0 = expand_binop (mode, and_optab, op0,
> + GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
> + NULL_RTX, true, OPTAB_WIDEN);
> + op1 = expand_binop (mode, and_optab, op1,
> + GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
> + NULL_RTX, true, OPTAB_WIDEN);
> + }
> + }
> +
Can we then remove the same code from do_compare_and_jump before the call to
do_compare_rtx_and_jump? I'll note that we don't pass 'val' there and
'val' is unfortunately
not documented - what's it supposed to be? I think I placed the original fix in
do_compare_and_jump because we have the full into available there. So
what's the
do_compare_rtx_and_jump caller that needs fixing as well? (IMHO keying on 'val'
looks fragile)
The other hunks below are OK.
Thanks,
Richard.
> emit_cmp_and_jump_insns (op0, op1, code, size, mode, unsignedp, val,
> if_true_label, prob);
> }
> diff --git a/gcc/internal-fn.cc b/gcc/internal-fn.cc
> index fcf47c7fa12..5269f0ac528 100644
> --- a/gcc/internal-fn.cc
> +++ b/gcc/internal-fn.cc
> @@ -245,6 +245,18 @@ expand_fn_using_insn (gcall *stmt, insn_code icode,
> unsigned int noutputs,
> && SSA_NAME_IS_DEFAULT_DEF (rhs)
> && VAR_P (SSA_NAME_VAR (rhs)))
> create_undefined_input_operand (&ops[opno], TYPE_MODE (rhs_type));
> + else if (VECTOR_BOOLEAN_TYPE_P (rhs_type)
> + && SCALAR_INT_MODE_P (TYPE_MODE (rhs_type))
> + && maybe_ne (GET_MODE_PRECISION (TYPE_MODE (rhs_type)),
> + TYPE_VECTOR_SUBPARTS (rhs_type).to_constant ()))
> + {
> + /* Ensure that the vector bitmasks do not have excess bits. */
> + int nunits = TYPE_VECTOR_SUBPARTS (rhs_type).to_constant ();
> + rtx tmp = expand_binop (TYPE_MODE (rhs_type), and_optab, rhs_rtx,
> + GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
> + NULL_RTX, true, OPTAB_WIDEN);
> + create_input_operand (&ops[opno], tmp, TYPE_MODE (rhs_type));
> + }
> else
> create_input_operand (&ops[opno], rhs_rtx, TYPE_MODE (rhs_type));
> opno += 1;
> @@ -312,6 +324,20 @@ add_mask_and_len_args (expand_operand *ops, unsigned int
> opno, gcall *stmt)
> {
> tree mask = gimple_call_arg (stmt, mask_index);
> rtx mask_rtx = expand_normal (mask);
> +
> + tree mask_type = TREE_TYPE (mask);
> + if (VECTOR_BOOLEAN_TYPE_P (mask_type)
> + && SCALAR_INT_MODE_P (TYPE_MODE (mask_type))
> + && maybe_ne (GET_MODE_PRECISION (TYPE_MODE (mask_type)),
> + TYPE_VECTOR_SUBPARTS (mask_type).to_constant ()))
> + {
> + /* Ensure that the vector bitmasks do not have excess bits. */
> + int nunits = TYPE_VECTOR_SUBPARTS (mask_type).to_constant ();
> + mask_rtx = expand_binop (TYPE_MODE (mask_type), and_optab, mask_rtx,
> + GEN_INT ((HOST_WIDE_INT_1U << nunits) - 1),
> + NULL_RTX, true, OPTAB_WIDEN);
> + }
> +
> create_input_operand (&ops[opno++], mask_rtx,
> TYPE_MODE (TREE_TYPE (mask)));
> }
> --
> 2.41.0
>
