https://gcc.gnu.org/g:e63b59a00257ac80d9d74acc7e131a8287940ff7

commit r16-6990-ge63b59a00257ac80d9d74acc7e131a8287940ff7
Author: Richard Biener <[email protected]>
Date:   Fri Jan 23 09:17:21 2026 +0100

    tree-optimization/123771 - missing conversion of induction step
    
    The following makes sure to convert an induction step to the vector
    component type from, for example _BitInt, before using it.
    
            PR tree-optimization/123771
            * tree-vect-loop.cc (vectorizable_induction): Convert step
            also for VLA vectors.

Diff:
---
 gcc/tree-vect-loop.cc | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index d3f9ffad52ec..73b103f3ee8a 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -9831,14 +9831,15 @@ vectorizable_induction (loop_vec_info loop_vinfo,
        }
       else
        {
+         tree step = gimple_convert (&init_stmts, stept, steps[0]);
          if (init_node)
            ;
-         else if (INTEGRAL_TYPE_P (TREE_TYPE (steps[0])))
+         else if (INTEGRAL_TYPE_P (stept))
            {
              new_name = gimple_convert (&init_stmts, stept, inits[0]);
              /* Build the initial value directly as a VEC_SERIES_EXPR.  */
              vec_init = gimple_build (&init_stmts, VEC_SERIES_EXPR,
-                                      step_vectype, new_name, steps[0]);
+                                      step_vectype, new_name, step);
              if (!useless_type_conversion_p (vectype, step_vectype))
                vec_init = gimple_build (&init_stmts, VIEW_CONVERT_EXPR,
                                         vectype, vec_init);
@@ -9848,19 +9849,18 @@ vectorizable_induction (loop_vec_info loop_vinfo,
              /* Build:
                 [base, base, base, ...]
                 + (vectype) [0, 1, 2, ...] * [step, step, step, ...].  */
-             gcc_assert (SCALAR_FLOAT_TYPE_P (TREE_TYPE (steps[0])));
+             gcc_assert (SCALAR_FLOAT_TYPE_P (stept));
              gcc_assert (flag_associative_math);
              gcc_assert (index_vectype != NULL_TREE);
 
              tree index = build_index_vector (index_vectype, 0, 1);
-             new_name = gimple_convert (&init_stmts, TREE_TYPE (steps[0]),
-                                        inits[0]);
+             new_name = gimple_convert (&init_stmts, stept, inits[0]);
              tree base_vec = gimple_build_vector_from_val (&init_stmts,
                                                            step_vectype,
                                                            new_name);
              tree step_vec = gimple_build_vector_from_val (&init_stmts,
                                                            step_vectype,
-                                                           steps[0]);
+                                                           step);
              vec_init = gimple_build (&init_stmts, FLOAT_EXPR,
                                       step_vectype, index);
              vec_init = gimple_build (&init_stmts, MULT_EXPR,
@@ -9873,7 +9873,7 @@ vectorizable_induction (loop_vec_info loop_vinfo,
            }
          /* iv_loop is nested in the loop to be vectorized. Generate:
             vec_step = [S, S, S, S]  */
-         t = unshare_expr (steps[0]);
+         t = unshare_expr (step);
          gcc_assert (CONSTANT_CLASS_P (t)
                      || TREE_CODE (t) == SSA_NAME);
          vec_step = gimple_build_vector_from_val (&init_stmts,

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