[gcc r12-7855] c++: low -faligned-new [PR102071]

[gcc r12-7855] c++: low -faligned-new [PR102071]

[Jason Merrill]

https://gcc.gnu.org/g:19b87a06482756739087283cd8b884cb3de693f9

commit r12-7855-g19b87a06482756739087283cd8b884cb3de693f9
Author: Jason Merrill <jason@redhat.com>
Date:   Sun Mar 27 12:36:13 2022 -0400

    c++: low -faligned-new [PR102071]
    
    This test ICEd after the constexpr new patch (r10-3661) because alloc_call
    had a NOP_EXPR around it; fixed by moving the NOP_EXPR to alloc_expr.  And
    the PR pointed out that the size_t cookie might need more alignment, so I
    fix that as well.
    
            PR c++/102071
    
    gcc/cp/ChangeLog:
    
            * init.cc (build_new_1): Include cookie in alignment.  Omit
            constexpr wrapper from alloc_call.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp1z/aligned-new9.C: New test.

Diff:
---
 gcc/cp/init.cc                            | 15 +++++++++++----
 gcc/testsuite/g++.dg/cpp1z/aligned-new9.C | 26 ++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 08767679dd4..91b5c2c0f69 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -3284,7 +3284,13 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
 
   tree align_arg = NULL_TREE;
   if (type_has_new_extended_alignment (elt_type))
-    align_arg = build_int_cst (align_type_node, TYPE_ALIGN_UNIT (elt_type));
+    {
+      unsigned align = TYPE_ALIGN_UNIT (elt_type);
+      /* Also consider the alignment of the cookie, if any.  */
+      if (TYPE_VEC_NEW_USES_COOKIE (elt_type))
+	align = MAX (align, TYPE_ALIGN_UNIT (size_type_node));
+      align_arg = build_int_cst (align_type_node, align);
+    }
 
   alloc_fn = NULL_TREE;
 
@@ -3473,18 +3479,19 @@ build_new_1 (vec<tree, va_gc> **placement, tree type, tree nelts,
 	}
     }
 
+  alloc_expr = alloc_call;
   if (cookie_size)
-    alloc_call = maybe_wrap_new_for_constexpr (alloc_call, type,
+    alloc_expr = maybe_wrap_new_for_constexpr (alloc_expr, type,
 					       cookie_size);
 
   /* In the simple case, we can stop now.  */
   pointer_type = build_pointer_type (type);
   if (!cookie_size && !is_initialized && !member_delete_p)
-    return build_nop (pointer_type, alloc_call);
+    return build_nop (pointer_type, alloc_expr);
 
   /* Store the result of the allocation call in a variable so that we can
      use it more than once.  */
-  alloc_expr = get_target_expr (alloc_call);
+  alloc_expr = get_target_expr (alloc_expr);
   alloc_node = TARGET_EXPR_SLOT (alloc_expr);
 
   /* Strip any COMPOUND_EXPRs from ALLOC_CALL.  */
diff --git a/gcc/testsuite/g++.dg/cpp1z/aligned-new9.C b/gcc/testsuite/g++.dg/cpp1z/aligned-new9.C
new file mode 100644
index 00000000000..7854299419a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/aligned-new9.C
@@ -0,0 +1,26 @@
+// PR c++/102071
+// { dg-do run { target c++17 } }
+// { dg-additional-options -faligned-new=2 }
+
+#include <new>
+
+int nalign;
+void *operator new (std::size_t s, std::align_val_t a)
+{
+  nalign = (int)a;
+  return operator new (s);
+}
+
+struct X { ~X(); int c; };
+
+int align = (alignof (X) > alignof (std::size_t)
+	     ? alignof (X) : alignof (std::size_t));
+
+int n = 4;
+
+int main()
+{
+  X *p = new X[n];
+  if (nalign != align)
+    __builtin_abort ();
+}