[gcc(refs/users/meissner/heads/work221-sha)] PR target/117251: Improve vector and to vector nor fusion

[Michael Meissner]

https://gcc.gnu.org/g:2988d5aaa8c2f850e2fadef7f47fc74f57104d32

commit 2988d5aaa8c2f850e2fadef7f47fc74f57104d32
Author: Michael Meissner <meissner@linux.ibm.com>
Date:   Mon Sep 8 15:41:28 2025 -0400

    PR target/117251: Improve vector and to vector nor fusion
    
    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 #34 of 45 to generate the 'XXEVAL' instruction on power10
    and power11 instead of using the Altivec 'VAND' instruction feeding
    into 'VNOR'.  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:
    
            vand   t,c,d
            vnor   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,224
    
    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?
    
    2025-09-08  Michael Meissner  <meissner@linux.ibm.com>
    
    gcc/
    
            PR target/117251
            * config/rs6000/fusion.md: Regenerate.
            * config/rs6000/genfusion.pl (gen_logical_addsubf): Add support
            to generate vector and => nor fusion if XXEVAL is supported.

Diff:
---
 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 e3d9f7376a8d..68b52d4f5893 100644
--- a/gcc/config/rs6000/fusion.md
+++ b/gcc/config/rs6000/fusion.md
@@ -2480,20 +2480,23 @@
 ;; logical-logical fusion pattern generated by gen_logical_addsubf
 ;; vector vand -> vnor
 (define_insn "*fuse_vand_vnor"
-  [(set (match_operand:VM 3 "altivec_register_operand" "=&0,&1,&v,v")
-        (and:VM (not:VM (and:VM (match_operand:VM 0 "altivec_register_operand" "v,v,v,v")
-                          (match_operand:VM 1 "altivec_register_operand" "v,v,v,v")))
-                 (not:VM (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")
+        (and:VM (not:VM (and:VM (match_operand:VM 0 "vector_fusion_operand" "v,v,v,wa,v")
+                          (match_operand:VM 1 "vector_fusion_operand" "v,v,v,wa,v")))
+                 (not:VM (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)"
   "@
    vand %3,%1,%0\;vnor %3,%3,%2
    vand %3,%1,%0\;vnor %3,%3,%2
    vand %3,%1,%0\;vnor %3,%3,%2
+   xxeval %x3,%x2,%x1,%x0,224
    vand %4,%1,%0\;vnor %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 vandc -> vnor
diff --git a/gcc/config/rs6000/genfusion.pl b/gcc/config/rs6000/genfusion.pl
index 3a603eb09675..56e5d96ec5f3 100755
--- a/gcc/config/rs6000/genfusion.pl
+++ b/gcc/config/rs6000/genfusion.pl
@@ -248,6 +248,7 @@ sub gen_logical_addsubf
       "vorc_vor"    => 191,
       "vandc_vnor"  => 208,
       "vandc_veqv"  => 210,
+      "vand_vnor"   => 224,
     );
 
     KIND: foreach $kind ('scalar','vector') {