On Wed, Nov 30, 2022 at 04:30:13PM +0800, Kewen.Lin wrote:
> As PR104024 shows, the option -mpower10-fusion isn't guarded by
> -mcpu=power10, it causes compiler to fuse for some patterns
> even without power10 support and then causes ICE unexpectedly,
> this patch is to simply unmask it without power10 support, not
> emit any warnings as this option is undocumented.
Yes, it mostly exists for debugging purposes (and also for testcase).
> Besides, for some define_insns in fusion.md which use constraint
> v, it requires the condition VECTOR_UNIT_ALTIVEC_OR_VSX_P
> (<MODE>mode), otherwise it can cause ICE in reload, see test
> case pr104024-2.c.
Please don't two separate things in one patch. It makes bisecting
harder than necessary, and perhaps more interesting to you: it makes
writing good changelog entries and commit messages harder.
> --- a/gcc/config/rs6000/genfusion.pl
> +++ b/gcc/config/rs6000/genfusion.pl
> @@ -167,7 +167,7 @@ sub gen_logical_addsubf
> $inner_comp, $inner_inv, $inner_rtl, $inner_op, $both_commute, $c4,
> $bc, $inner_arg0, $inner_arg1, $inner_exp, $outer_arg2, $outer_exp,
> $ftype, $insn, $is_subf, $is_rsubf, $outer_32, $outer_42,$outer_name,
> - $fuse_type);
> + $fuse_type, $constraint_cond);
> KIND: foreach $kind ('scalar','vector') {
> @outer_ops = @logicals;
> if ( $kind eq 'vector' ) {
> @@ -176,12 +176,14 @@ sub gen_logical_addsubf
> $pred = "altivec_register_operand";
> $constraint = "v";
> $fuse_type = "fused_vector";
> + $constraint_cond = "VECTOR_UNIT_ALTIVEC_OR_VSX_P (<MODE>mode) && ";
> } else {
> $vchr = "";
> $mode = "GPR";
> $pred = "gpc_reg_operand";
> $constraint = "r";
> $fuse_type = "fused_arith_logical";
> + $constraint_cond = "";
> push (@outer_ops, @addsub);
> push (@outer_ops, ( "rsubf" ));
> }
I don't like this at all. Please use the "isa" attribute where needed?
Or do you need more in some cases? But, again, separate patch.
> + if (TARGET_POWER10
> + && (rs6000_isa_flags_explicit & OPTION_MASK_P10_FUSION) == 0)
> + rs6000_isa_flags |= OPTION_MASK_P10_FUSION;
> + else if (!TARGET_POWER10 && TARGET_P10_FUSION)
> + rs6000_isa_flags &= ~OPTION_MASK_P10_FUSION;
That's not right. If you want something like this you should check for
TARGET_POWER10 whenever you check for TARGET_P10_FUSION; but there
really is no reason at all to disable P10 fusion on other CPUs (neither
newer nor older!).
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr104024-1.c
> @@ -0,0 +1,16 @@
> +/* { dg-require-effective-target int128 } */
> +/* { dg-options "-O1 -mdejagnu-cpu=power6 -mpower10-fusion" } */
Does this need -O1? If not, use -O2 please; if so, document it.
Segher
