[committed] d: Fix -fpreview=in ICEs with forward referenced parameter [PR112285]

[committed] d: Fix -fpreview=in ICEs with forward referenced parameter [PR112285]

[Iain Buclaw]

Hi,

This patch removes the early lowering of D AST types as GCC trees in
Target::preferPassByRef, fixing both PR12285 and PR12290.

The way that the target hook preferPassByRef is implemented, it relied
on the GCC "back-end" tree type to determine whether or not to use `ref'
ABI for D `in' parameters; e.g: prefer by value if it is expected that
the target will pass the type around in registers.

Building the GCC tree type depends on the AST type being complete - all
semantic processing is finished - but as this hook is called from the
front-end, this will not be the case for forward referenced or
self-referencing types.

The consensus in upstream is that `in' parameters should always be
implicitly `ref', but as the front-end does not yet support all types
being rvalue references, limit this just static arrays and structs.

Bootstrapped and regression tested on x86_64-linux-gnu/-m32, committed
to mainline and backported to releases/gcc-13 and releases/gcc-12.

Regards,
Iain.

---
	PR d/112285
	PR d/112290

gcc/d/ChangeLog:

	* d-target.cc (Target::preferPassByRef): Return true for all static
	array and struct types.

gcc/testsuite/ChangeLog:

	* gdc.dg/pr112285.d: New test.
	* gdc.dg/pr112290.d: New test.
---
 gcc/d/d-target.cc               | 25 +++++--------------------
 gcc/testsuite/gdc.dg/pr112285.d | 13 +++++++++++++
 gcc/testsuite/gdc.dg/pr112290.d | 15 +++++++++++++++
 3 files changed, 33 insertions(+), 20 deletions(-)
 create mode 100644 gcc/testsuite/gdc.dg/pr112285.d
 create mode 100644 gcc/testsuite/gdc.dg/pr112290.d

diff --git a/gcc/d/d-target.cc b/gcc/d/d-target.cc
index b9d124422b7..9b69b0bc873 100644
--- a/gcc/d/d-target.cc
+++ b/gcc/d/d-target.cc
@@ -575,31 +575,16 @@ Target::supportsLinkerDirective (void) const
 }
 
 /* Decides whether an `in' parameter of the specified POD type PARAM_TYPE is to
-   be passed by reference or by valie.  This is used only when compiling with
+   be passed by reference or by value.  This is used only when compiling with
    `-fpreview=in' enabled.  */
 
 bool
 Target::preferPassByRef (Type *param_type)
 {
-  if (param_type->size () == SIZE_INVALID)
+  /* See note in Target::isReturnOnStack.  */
+  Type *tb = param_type->toBasetype ();
+  if (tb->size () == SIZE_INVALID)
     return false;
 
-  tree type = build_ctype (param_type);
-
-  /* Prefer a `ref' if the type is an aggregate, and its size is greater than
-     its alignment.  */
-  if (AGGREGATE_TYPE_P (type)
-      && (!valid_constant_size_p (TYPE_SIZE_UNIT (type))
-	  || compare_tree_int (TYPE_SIZE_UNIT (type), TYPE_ALIGN (type)) > 0))
-    return true;
-
-  /* If the back-end is always going to pass this by invisible reference.  */
-  if (pass_by_reference (NULL, function_arg_info (type, true)))
-    return true;
-
-  /* If returning the parameter means the caller will do RVO.  */
-  if (targetm.calls.return_in_memory (type, NULL_TREE))
-    return true;
-
-  return false;
+  return (tb->ty == TY::Tstruct || tb->ty == TY::Tsarray);
 }
diff --git a/gcc/testsuite/gdc.dg/pr112285.d b/gcc/testsuite/gdc.dg/pr112285.d
new file mode 100644
index 00000000000..5ca100a74a9
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr112285.d
@@ -0,0 +1,13 @@
+// { dg-do compile }
+// { dg-additional-options "-fpreview=in" }
+struct S112285
+{
+}
+
+class C112285
+{
+    S112285 s;
+    void f112285(in C112285)
+    {
+    }
+}
diff --git a/gcc/testsuite/gdc.dg/pr112290.d b/gcc/testsuite/gdc.dg/pr112290.d
new file mode 100644
index 00000000000..7456fc21be1
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/pr112290.d
@@ -0,0 +1,15 @@
+// { dg-do compile }
+// { dg-additional-options "-fpreview=in" }
+struct S112290a
+{
+    S112290b* p;
+    bool opEquals(in S112290a)
+    {
+        return p == p;
+    }
+}
+
+struct S112290b
+{
+    string s;
+}
-- 
2.40.1