[gcc r15-9329] expr: Use constant_lower_bound classifying constructor els [PR116595].

[Robin Dapp via Gcc-cvs]

https://gcc.gnu.org/g:f183ae0ae891a471764876eb1e69239904598bb4

commit r15-9329-gf183ae0ae891a471764876eb1e69239904598bb4
Author: Robin Dapp <rd...@ventanamicro.com>
Date:   Thu Apr 3 16:46:05 2025 +0200

    expr: Use constant_lower_bound classifying constructor els [PR116595].
    
    In categorize_ctor_elements_1 we do
      VECTOR_CST_NELTS (value).to_constant ()
    but VALUE's type can be a VLA vector (since r15-5780-g17b520a10cdaab).
    
    This patch uses constant_lower_bound instead.
    
            PR middle-end/116595
    
    gcc/ChangeLog:
    
            * expr.cc (categorize_ctor_elements_1): Use
            constant_lower_bound.
    
    gcc/testsuite/ChangeLog:
    
            * g++.target/riscv/rvv/autovec/pr116595.C: New test.

Diff:
---
 gcc/expr.cc                                           |  6 +++---
 gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C | 10 ++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 2147eedad7be..3815c565e2d8 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -7193,9 +7193,9 @@ categorize_ctor_elements_1 (const_tree ctor, 
HOST_WIDE_INT *p_nz_elts,
 
        case VECTOR_CST:
          {
-           /* We can only construct constant-length vectors using
-              CONSTRUCTOR.  */
-           unsigned int nunits = VECTOR_CST_NELTS (value).to_constant ();
+           unsigned int nunits
+             = constant_lower_bound
+             (TYPE_VECTOR_SUBPARTS (TREE_TYPE (value)));
            for (unsigned int i = 0; i < nunits; ++i)
              {
                tree v = VECTOR_CST_ELT (value, i);
diff --git a/gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C 
b/gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C
new file mode 100644
index 000000000000..6d509d2cf74e
--- /dev/null
+++ b/gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gcv" } */
+
+#include <riscv_vector.h>
+
+void
+vsseg (float *a, vfloat32mf2_t b, vfloat32mf2_t c, unsigned long vl)
+{
+  vfloat32mf2x2_t foo = vfloat32mf2x2_t ();
+}