From b30aeaa173b6886cda15570a2e23eac1136665bf Mon Sep 17 00:00:00 2001
From: Iain Buclaw <ibuclaw@gdcproject.org>
Date: Tue, 25 Aug 2020 00:39:17 +0200
Subject: [PATCH] d: Fix no NRVO when returning an array of a non-POD struct

TREE_ADDRESSABLE was not propagated from the RECORD_TYPE to the ARRAY_TYPE, so
NRVO code generation was not being triggered.

gcc/d/ChangeLog:

	PR d/96157
	* d-codegen.cc (d_build_call): Handle TREE_ADDRESSABLE static arrays.
	* types.cc (make_array_type): Propagate TREE_ADDRESSABLE from base
	type to static array.

gcc/testsuite/ChangeLog:

	PR d/96157
	* gdc.dg/pr96157a.d: New test.
	* gdc.dg/pr96157b.d: New test.

(cherry picked from commit 312ad889e99ff9458c01518325775e75ab57f272)
---
 gcc/d/d-codegen.cc              |  4 +--
 gcc/d/types.cc                  |  7 +++--
 gcc/testsuite/gdc.dg/pr96157a.d | 24 +++++++++++++++++
 gcc/testsuite/gdc.dg/pr96157b.d | 46 +++++++++++++++++++++++++++++++++
 4 files changed, 77 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gdc.dg/pr96157a.d
 create mode 100644 gcc/testsuite/gdc.dg/pr96157b.d

diff --git a/gcc/d/d-codegen.cc b/gcc/d/d-codegen.cc
index b5af2aca0a9a..f57caf226d40 100644
--- a/gcc/d/d-codegen.cc
+++ b/gcc/d/d-codegen.cc
@@ -1910,10 +1910,10 @@ d_build_call (TypeFunction *tf, tree callable, tree object,
 	      targ = build2 (COMPOUND_EXPR, TREE_TYPE (t), targ, t);
 	    }
 
-	  /* Parameter is a struct passed by invisible reference.  */
+	  /* Parameter is a struct or array passed by invisible reference.  */
 	  if (TREE_ADDRESSABLE (TREE_TYPE (targ)))
 	    {
-	      Type *t = arg->type->toBasetype ();
+	      Type *t = arg->type->toBasetype ()->baseElemOf ();
 	      gcc_assert (t->ty == Tstruct);
 	      StructDeclaration *sd = ((TypeStruct *) t)->sym;
 
diff --git a/gcc/d/types.cc b/gcc/d/types.cc
index 59a90b492438..d6607a30b7ba 100644
--- a/gcc/d/types.cc
+++ b/gcc/d/types.cc
@@ -142,8 +142,11 @@ make_array_type (Type *type, unsigned HOST_WIDE_INT size)
       return t;
     }
 
-  return build_array_type (build_ctype (type),
-			   build_index_type (size_int (size - 1)));
+  tree t = build_array_type (build_ctype (type),
+			     build_index_type (size_int (size - 1)));
+  /* Propagate TREE_ADDRESSABLE to the static array type.  */
+  TREE_ADDRESSABLE (t) = TREE_ADDRESSABLE (TREE_TYPE (t));
+  return t;
 }
 
 /* Builds a record type whose name is NAME.  NFIELDS is the number of fields,
diff --git a/gcc/testsuite/gdc.dg/pr96157a.d b/gcc/testsuite/gdc.dg/pr96157a.d
new file mode 100644
index 000000000000..11df19ea700c
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr96157a.d
@@ -0,0 +1,24 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96157
+// { dg-do run { target native } }
+// { dg-skip-if "needs gcc/config.d" { ! d_runtime } }
+
+struct S
+{
+    @disable this(this); // triggers nrvo
+    int v;
+}
+
+__gshared void* p;
+
+S[1000] foo() nothrow
+{
+    typeof(return) d;
+    p = &d;
+    return d;
+}
+
+void main()
+{
+    auto d = foo();
+    assert(p == &d);
+}
diff --git a/gcc/testsuite/gdc.dg/pr96157b.d b/gcc/testsuite/gdc.dg/pr96157b.d
new file mode 100644
index 000000000000..40a7e0ba787d
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr96157b.d
@@ -0,0 +1,46 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96157
+// { dg-options "-fno-moduleinfo -fno-rtti" }
+// { dg-do compile }
+
+int[] testYearsBC;
+
+struct FilterResult
+{
+    int[] input;
+    bool primed;
+
+    this(int[] r)
+    {
+        this.input = r;
+    }
+
+    int front()
+    {
+        return input[0];
+    }
+};
+
+FilterResult filter(int[] range)
+{
+    return FilterResult(range);
+}
+
+int[] chain(int[] rs)
+{
+    return rs;
+}
+
+struct SysTime
+{
+    this(int);
+}
+
+void test()
+{
+    while (1)
+    {
+        FilterResult val = filter(chain(testYearsBC));
+        int year = val.front();
+        SysTime(0);
+    }
+}
-- 
2.43.5