https://gcc.gnu.org/g:ad81d6531bf12016615d8538a0b8ed5958b18b5a
commit ad81d6531bf12016615d8538a0b8ed5958b18b5a
Author: Michael Meissner <meiss...@linux.ibm.com>
Date: Wed Jul 9 01:55:54 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?
2025-07-09 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 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 129f7dfb26ed..61d66129da65 100644
--- a/gcc/config/rs6000/fusion.md
+++ b/gcc/config/rs6000/fusion.md
@@ -2336,20 +2336,23 @@
;; logical-logical fusion pattern generated by gen_logical_addsubf
;; vector vand -> vnand
(define_insn "*fuse_vand_vnand"
- [(set (match_operand:VM 3 "altivec_register_operand" "=&0,&1,&v,v")
- (ior: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")
+ (ior: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\;vnand %3,%3,%2
vand %3,%1,%0\;vnand %3,%3,%2
vand %3,%1,%0\;vnand %3,%3,%2
+ xxeval %x3,%x2,%x1,%x0,254
vand %4,%1,%0\;vnand %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 -> vnand
diff --git a/gcc/config/rs6000/genfusion.pl b/gcc/config/rs6000/genfusion.pl
index 1d31c242042e..9261dd369340 100755
--- a/gcc/config/rs6000/genfusion.pl
+++ b/gcc/config/rs6000/genfusion.pl
@@ -258,6 +258,7 @@ sub gen_logical_addsubf
"vor_vnand" => 248,
"vxor_vnand" => 249,
"vandc_vnand" => 253,
+ "vand_vnand" => 254,
);
KIND: foreach $kind ('scalar','vector') {
