[gcc(refs/vendors/riscv/heads/gcc-14-with-riscv-opts)] RISC-V: Use encoded nelts when calling repeating_sequence_p

[Jeff Law via Gcc-cvs]

https://gcc.gnu.org/g:3ee78b3342cbe83e3498fd0b355e57ff9a30966d

commit 3ee78b3342cbe83e3498fd0b355e57ff9a30966d
Author: Patrick O'Neill <patr...@rivosinc.com>
Date:   Mon Aug 19 12:19:33 2024 -0700

    RISC-V: Use encoded nelts when calling repeating_sequence_p
    
    repeating_sequence_p operates directly on the encoded pattern and does
    not derive elements using the .elt() accessor. Passing in the length of
    the unencoded vector can cause an out-of-bounds read of the encoded
    pattern.
    
    gcc/ChangeLog:
    
            * config/riscv/riscv-v.cc 
(rvv_builder::can_duplicate_repeating_sequence_p):
            Use encoded_nelts when calling repeating_sequence_p.
            (rvv_builder::is_repeating_sequence): Ditto.
            (rvv_builder::repeating_sequence_use_merge_profitable_p): Ditto.
    
    Signed-off-by: Patrick O'Neill <patr...@rivosinc.com>
    (cherry picked from commit 5dce17e17469161f413e1a5b723dca0e94be3fb6)

Diff:
---
 gcc/config/riscv/riscv-v.cc | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/gcc/config/riscv/riscv-v.cc b/gcc/config/riscv/riscv-v.cc
index 0db5c7591eff..c89603669e3a 100644
--- a/gcc/config/riscv/riscv-v.cc
+++ b/gcc/config/riscv/riscv-v.cc
@@ -502,9 +502,7 @@ rvv_builder::can_duplicate_repeating_sequence_p ()
       || GET_MODE_SIZE (m_new_inner_mode) > UNITS_PER_WORD
       || !get_vector_mode (m_new_inner_mode, new_size).exists (&m_new_mode))
     return false;
-  if (full_nelts ().is_constant ())
-    return repeating_sequence_p (0, full_nelts ().to_constant (), npatterns 
());
-  return nelts_per_pattern () == 1;
+  return repeating_sequence_p (0, encoded_nelts (), npatterns ());
 }
 
 /* Return true if the vector is a simple sequence with one pattern and all
@@ -514,9 +512,7 @@ rvv_builder::is_repeating_sequence ()
 {
   if (npatterns () > 1)
     return false;
-  if (full_nelts ().is_constant ())
-    return repeating_sequence_p (0, full_nelts ().to_constant (), 1);
-  return nelts_per_pattern () == 1;
+  return repeating_sequence_p (0, encoded_nelts (), 1);
 }
 
 /* Return true if it is a repeating sequence that using
@@ -564,7 +560,7 @@ rvv_builder::repeating_sequence_use_merge_profitable_p ()
 
   unsigned int nelts = full_nelts ().to_constant ();
 
-  if (!repeating_sequence_p (0, nelts, npatterns ()))
+  if (!repeating_sequence_p (0, encoded_nelts (), npatterns ()))
     return false;
 
   unsigned int merge_cost = 1;