From f183ae0ae891a471764876eb1e69239904598bb4 Mon Sep 17 00:00:00 2001
From: Robin Dapp <rdapp@ventanamicro.com>
Date: Thu, 3 Apr 2025 16:46:05 +0200
Subject: [PATCH] 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.
---
 gcc/expr.cc                                           |  6 +++---
 gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C | 10 ++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.target/riscv/rvv/autovec/pr116595.C

diff --git a/gcc/expr.cc b/gcc/expr.cc
index 2147eedad7b..3815c565e2d 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 00000000000..6d509d2cf74
--- /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 ();
+}