On Wed, 2020-08-26 at 22:44 -0400, Michael Meissner via Gcc-patches wrote:
> PowerPC: Rename functions for min, max, cmove.
>
> This patch renames the functions that generate the ISA 3.0 C minimum, C
> maximum, and conditional move instructions to use a better name than just
> using
> a _p9 suffix. Because the functions can fail, the names use "maybe_emit"
> instead of "generate_" in the name.
>
> I have built compilers on a little endian power9 Linux system with all 4
> patches applied. I did bootstrap builds and ran the testsuite, with no
> regressions. Previous versions of the patch was also tested on a little
> endian
> power8 Linux system. I would like to check this patch into the master
> branch for GCC 11. At this time, I do not anticipate needing to backport
> these
> changes to GCC 10.3.
>
> gcc/
> 2020-08-26 Michael Meissner <meiss...@linux.ibm.com>
>
> * config/rs6000/rs6000.c (rs6000_emit_p9_fp_minmax): Rename to
> maybe_emit_fp_c_minmax.
ok
> (maybe_emit_fp_c_minmax): Rename rs6000_emit_p9_fp_minmax. Return
> bool instead of int.
function rename is redundant between the two entries?
> (rs6000_emit_p9_fp_cmove): Rename to maybe_emit_fp_cmove.
> (maybe_emit_fp_cmove): Rename rs6000_emit_p9_fp_cmove. Return
> bool instead of int.
Function rename comment is redundant ?
> (have_compare_and_set_mask): New helper function.
> (rs6000_emit_cmove): Rework support of ISA 3.0 functions to
> generate "C" minimum, "C" maximum, and conditional move
> instructions for scalar floating point.
>
Nothing else jumped out at me below.
lgtm, thanks,
-Will
> ---
> gcc/config/rs6000/rs6000.c | 77 ++++++++++++++++++++++++++------------
> 1 file changed, 53 insertions(+), 24 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index bac50c2bcf6..6324f930628 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -15056,13 +15056,17 @@ rs6000_emit_vector_cond_expr (rtx dest, rtx
> op_true, rtx op_false,
> return 1;
> }
>
> -/* ISA 3.0 (power9) minmax subcase to emit a XSMAXCDP or XSMINCDP instruction
> - for SF/DF scalars. Move TRUE_COND to DEST if OP of the operands of the
> last
> - comparison is nonzero/true, FALSE_COND if it is zero/false. Return 0 if
> the
> - hardware has no such operation. */
> +/* Possibly emit the C variant of the minimum or maximum instruction for
> + floating point scalars (xsmincdp, xsmaxcdp, etc.).
>
> -static int
> -rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> + Move TRUE_COND to DEST if OP of the operands of the last comparison is
> + nonzero/true, FALSE_COND if it is zero/false.
> +
> + Return false if we can't generate the appropriate minimum or maximum, and
> + true if we can did the minimum or maximum. */
> +
> +static bool
> +maybe_emit_fp_c_minmax (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> {
> enum rtx_code code = GET_CODE (op);
> rtx op0 = XEXP (op, 0);
> @@ -15072,14 +15076,14 @@ rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx
> true_cond, rtx false_cond)
> bool max_p = false;
>
> if (result_mode != compare_mode)
> - return 0;
> + return false;
>
> if (code == GE || code == GT)
> max_p = true;
> else if (code == LE || code == LT)
> max_p = false;
> else
> - return 0;
> + return false;
>
> if (rtx_equal_p (op0, true_cond) && rtx_equal_p (op1, false_cond))
> ;
> @@ -15092,19 +15096,23 @@ rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx
> true_cond, rtx false_cond)
> max_p = !max_p;
>
> else
> - return 0;
> + return false;
>
> rs6000_emit_minmax (dest, max_p ? SMAX : SMIN, op0, op1);
> - return 1;
> + return true;
> }
>
> -/* ISA 3.0 (power9) conditional move subcase to emit XSCMP{EQ,GE,GT,NE}DP and
> - XXSEL instructions for SF/DF scalars. Move TRUE_COND to DEST if OP of the
> - operands of the last comparison is nonzero/true, FALSE_COND if it is
> - zero/false. Return 0 if the hardware has no such operation. */
> +/* Possibly emit a floating point conditional move by generating a compare
> that
> + sets a mask instruction and a XXSEL select instruction.
>
> -static int
> -rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> + Move TRUE_COND to DEST if OP of the operands of the last comparison is
> + nonzero/true, FALSE_COND if it is zero/false.
> +
> + Return false if the operation cannot be generated, and true if we could
> + generate the instruction. */
> +
> +static bool
> +maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> {
> enum rtx_code code = GET_CODE (op);
> rtx op0 = XEXP (op, 0);
> @@ -15132,7 +15140,7 @@ rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx
> true_cond, rtx false_cond)
> break;
>
> default:
> - return 0;
> + return false;
> }
>
> /* Generate: [(parallel [(set (dest)
> @@ -15152,7 +15160,28 @@ rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx
> true_cond, rtx false_cond)
> emit_insn (gen_rtx_PARALLEL (VOIDmode,
> gen_rtvec (2, cmove_rtx, clobber_rtx)));
>
> - return 1;
> + return true;
> +}
> +
> +/* Helper function to return true if the target has instructions to do a
> + compare and set mask instruction that can be used with XXSEL to implement
> a
> + conditional move. It is also assumed that such a target also supports the
> + "C" minimum and maximum instructions. */
> +
> +static bool
> +have_compare_and_set_mask (machine_mode mode)
> +{
> + switch (mode)
> + {
> + case SFmode:
> + case DFmode:
> + return TARGET_P9_MINMAX;
> +
> + default:
> + break;
> + }
> +
> + return false;
> }
>
> /* Emit a conditional move: move TRUE_COND to DEST if OP of the
> @@ -15181,15 +15210,15 @@ rs6000_emit_cmove (rtx dest, rtx op, rtx true_cond,
> rtx false_cond)
> if (GET_MODE (false_cond) != result_mode)
> return false;
>
> - /* See if we can use the ISA 3.0 (power9) min/max/compare functions. */
> - if (TARGET_P9_MINMAX
> - && (compare_mode == SFmode || compare_mode == DFmode)
> - && (result_mode == SFmode || result_mode == DFmode))
> + /* See if we can use the "C" minimum, "C" maximum, and compare and set mask
> + instructions. */
> + if (have_compare_and_set_mask (compare_mode)
> + && have_compare_and_set_mask (result_mode))
> {
> - if (rs6000_emit_p9_fp_minmax (dest, op, true_cond, false_cond))
> + if (maybe_emit_fp_c_minmax (dest, op, true_cond, false_cond))
> return true;
>
> - if (rs6000_emit_p9_fp_cmove (dest, op, true_cond, false_cond))
> + if (maybe_emit_fp_cmove (dest, op, true_cond, false_cond))
> return true;
> }
>
> --
> 2.22.0
>
>
