See the following post for a complete explanation of what the patches for PR target/117251:
* https://gcc.gnu.org/pipermail/gcc-patches/2025-June/686474.html This is patch #35 of 45 to generate the 'XXEVAL' instruction on power10 and power11 instead of using the Altivec 'VNAND' instruction feeding into 'VXOR'. The 'XXEVAL' instruction can use all 64 vector registers, instead of the 32 registers that traditional Altivec vector instructions use. By allowing all of the vector registers to be used, it reduces the amount of spilling that a large benchmark generated. Currently the following code: vector int a, b, c, d; a = (~ (c & d)) ^ b; Generates: vnand t,c,d vxor a,t,b Now in addition with this patch, if the arguments or result is allocated to a traditional FPR register, the GCC compiler will now generate the following code instead of adding vector move instructions: xxeval a,b,c,225 Since fusion using 2 Altivec instructions is slightly faster than using the 'XXEVAL' instruction we prefer to generate the Altivec instructions if we can. In addition, because 'XXEVAL' is a prefixed instruction, it possibly might generate an extra NOP instruction to align the 'XXEVAL' instruction. I have tested these patches on both big endian and little endian PowerPC servers, with no regressions. Can I check these patchs into the trunk? 2025-06-11 Michael Meissner <meiss...@linux.ibm.com> gcc/ PR target/117251 * config/rs6000/fusion.md: Regenerate. * config/rs6000/genfusion.pl (gen_logical_addsubf): Add support to generate vector nand => xor fusion if XXEVAL is supported. --- gcc/config/rs6000/fusion.md | 15 +++++++++------ gcc/config/rs6000/genfusion.pl | 1 + 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/gcc/config/rs6000/fusion.md b/gcc/config/rs6000/fusion.md index 68b52d4f589..e6d13b38415 100644 --- a/gcc/config/rs6000/fusion.md +++ b/gcc/config/rs6000/fusion.md @@ -3023,20 +3023,23 @@ (define_insn "*fuse_veqv_vxor" ;; logical-logical fusion pattern generated by gen_logical_addsubf ;; vector vnand -> vxor (define_insn "*fuse_vnand_vxor" - [(set (match_operand:VM 3 "altivec_register_operand" "=&0,&1,&v,v") - (xor:VM (ior:VM (not:VM (match_operand:VM 0 "altivec_register_operand" "v,v,v,v")) - (not:VM (match_operand:VM 1 "altivec_register_operand" "v,v,v,v"))) - (match_operand:VM 2 "altivec_register_operand" "v,v,v,v"))) - (clobber (match_scratch:VM 4 "=X,X,X,&v"))] + [(set (match_operand:VM 3 "vector_fusion_operand" "=&0,&1,&v,wa,v") + (xor:VM (ior:VM (not:VM (match_operand:VM 0 "vector_fusion_operand" "v,v,v,wa,v")) + (not:VM (match_operand:VM 1 "vector_fusion_operand" "v,v,v,wa,v"))) + (match_operand:VM 2 "vector_fusion_operand" "v,v,v,wa,v"))) + (clobber (match_scratch:VM 4 "=X,X,X,X,&v"))] "(TARGET_P10_FUSION)" "@ vnand %3,%1,%0\;vxor %3,%3,%2 vnand %3,%1,%0\;vxor %3,%3,%2 vnand %3,%1,%0\;vxor %3,%3,%2 + xxeval %x3,%x2,%x1,%x0,225 vnand %4,%1,%0\;vxor %3,%4,%2" [(set_attr "type" "fused_vector") (set_attr "cost" "6") - (set_attr "length" "8")]) + (set_attr "length" "8") + (set_attr "prefixed" "*,*,*,yes,*") + (set_attr "isa" "*,*,*,xxeval,*")]) ;; logical-logical fusion pattern generated by gen_logical_addsubf ;; vector vnor -> vxor diff --git a/gcc/config/rs6000/genfusion.pl b/gcc/config/rs6000/genfusion.pl index 56e5d96ec5f..94eae471c64 100755 --- a/gcc/config/rs6000/genfusion.pl +++ b/gcc/config/rs6000/genfusion.pl @@ -249,6 +249,7 @@ sub gen_logical_addsubf "vandc_vnor" => 208, "vandc_veqv" => 210, "vand_vnor" => 224, + "vnand_vxor" => 225, ); KIND: foreach $kind ('scalar','vector') { -- 2.49.0 -- Michael Meissner, IBM PO Box 98, Ayer, Massachusetts, USA, 01432 email: meiss...@linux.ibm.com
