Re: [PATCH] c++: Add support for vec_dup to constexpr [PR118445]

[Jason Merrill]

On 1/13/25 4:55 PM, Andrew Pinski wrote:

With the addition of supporting operations on the SVE scalable vector types,
the vec_duplicate tree will show up in expressions and the constexpr handling
was not done for this tree code.
This is a simple fix to treat VEC_DUPLICATE like any other unary operator and 
allows
the constexpr-add-1.C testcase to work.

Built and tested for aarch64-linux-gnu.

OK.

        PR c++/118445

gcc/cp/ChangeLog:

        * constexpr.cc (cxx_eval_constant_expression): Handle VEC_DUPLICATE like
        a "normal" unary operator.
        (potential_constant_expression_1): Likewise.

gcc/testsuite/ChangeLog:

        * g++.target/aarch64/sve/constexpr-add-1.C: New test.

Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
  gcc/cp/constexpr.cc                              |  2 ++
  .../g++.target/aarch64/sve/constexpr-add-1.C     | 16 ++++++++++++++++
  2 files changed, 18 insertions(+)
  create mode 100644 gcc/testsuite/g++.target/aarch64/sve/constexpr-add-1.C

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 1345bc124ef..0896576fd28 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -8005,6 +8005,7 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, 
tree t,
      case BIT_NOT_EXPR:
      case TRUTH_NOT_EXPR:
      case FIXED_CONVERT_EXPR:
+    case VEC_DUPLICATE_EXPR:
        r = cxx_eval_unary_expression (ctx, t, lval,
                                     non_constant_p, overflow_p);
        break;
@@ -10344,6 +10345,7 @@ potential_constant_expression_1 (tree t, bool 
want_rval, bool strict, bool now,
      case UNARY_PLUS_EXPR:
      case UNARY_LEFT_FOLD_EXPR:
      case UNARY_RIGHT_FOLD_EXPR:
+    case VEC_DUPLICATE_EXPR:
      unary:
        return RECUR (TREE_OPERAND (t, 0), rval);

diff --git a/gcc/testsuite/g++.target/aarch64/sve/constexpr-add-1.C b/gcc/testsuite/g++.target/aarch64/sve/constexpr-add-1.C

new file mode 100644
index 00000000000..43489560c8a
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/sve/constexpr-add-1.C
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+/* PR C++/118445 */
+
+#include <arm_sve.h>
+
+/* See if constexpr handles VEC_DUPLICATE and SVE. */
+constexpr svfloat32_t f(svfloat32_t b, float a)
+{
+  return b + a;
+}
+
+svfloat32_t g(void)
+{
+  return f((svfloat32_t){1.0}, 2.0);
+}