[gcc(refs/vendors/riscv/heads/gcc-15-with-riscv-opts)] RISC-V: Combine vec_duplicate + vmslt.vv to vmslt.vx on GR2VR cost

[Jeff Law]

https://gcc.gnu.org/g:1e5e925c382649ed7bd0747ccdc30955fe96de35

commit 1e5e925c382649ed7bd0747ccdc30955fe96de35
Author: Pan Li <pan2.li@intel.com>
Date:   Mon Dec 8 20:45:56 2025 +0800

    RISC-V: Combine vec_duplicate + vmslt.vv to vmslt.vx on GR2VR cost
    
    This patch would like to combine the vec_duplicate + vmslt.wv to the
    vmslt.vx.  From example as below code.  The related pattern will depend
    on the cost of vec_duplicate from GR2VR.  Then the late-combine will
    take action if the cost of GR2VR is zero, and reject the combination
    if the GR2VR cost is greater than zero.
    
    Assume we have asm code like below, GR2VR cost is 0.
    
    Before this patch:
      11       beq a3,zero,.L8
      12       vsetvli a5,zero,e32,m1,ta,ma
      13       vmv.v.x v2,a2
      ...
      16   .L3:
      17       vsetvli a5,a3,e32,m1,ta,ma
      ...
      22       vmslt.vv v1,v2,v3
      ...
      25       bne a3,zero,.L3
    
    After this patch:
      11       beq a3,zero,.L8
      ...
      14    .L3:
      15       vsetvli a5,a3,e32,m1,ta,ma
      ...
      20       vmslt.vx v1,a2,v3
      ...
      23       bne a3,zero,.L3
    
    gcc/ChangeLog:
    
            * config/riscv/predicates.md: Append operator lt to
            the comparison_swappable_operator.
            * config/riscv/riscv-v.cc (get_swapped_cmp_rtx_code): Add
            swappable operator lt handing.
    
    Signed-off-by: Pan Li <pan2.li@intel.com>
    (cherry picked from commit d1f755115b4a53e866b7eb7a78df9bb2ff28d53a)

Diff:
---
 gcc/config/riscv/predicates.md | 2 +-
 gcc/config/riscv/riscv-v.cc    | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/config/riscv/predicates.md b/gcc/config/riscv/predicates.md
index 3cc954e10cc6..5b44165ec993 100644
--- a/gcc/config/riscv/predicates.md
+++ b/gcc/config/riscv/predicates.md
@@ -612,7 +612,7 @@
   (match_code "eq,ne,le,leu,gt,gtu,lt,ltu"))
 
 (define_predicate "comparison_swappable_operator"
-  (match_code "gtu"))
+  (match_code "gtu,gt"))
 
 (define_predicate "ge_operator"
   (match_code "ge,geu"))
diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
index fbf2e7a5c464..f3c44313967c 100644
--- a/gcc/config/riscv/riscv-v.cc
+++ b/gcc/config/riscv/riscv-v.cc
@@ -5917,6 +5917,8 @@ get_swapped_cmp_rtx_code (rtx_code code)
     {
     case GTU:
       return LTU;
+    case GT:
+      return LT;
     default:
       gcc_unreachable ();
     }