d: Add `@register' attribute to compiler and library.

The `@register` attribute specifies that a local or `__gshared` variable
is to be given a register storage-class in the C sense of the term, and
will be placed into a register named `registerName`.

The variable needs to boiled down to a data type that fits the target
register.  It also cannot have either thread-local or `extern` storage.
It is an error to take the address of a register variable.

	PR d/105413

gcc/d/ChangeLog:

	* d-attribs.cc (d_handle_register_attribute): New function.
	(d_langhook_attribute_table): Add register attribute.
	* d-codegen.cc (d_mark_addressable): Error if taken address of
	register variable.
	(build_frame_type): Error if register variable has non-local
	references.
	* d-tree.h (d_mark_addressable): Add complain parameter.
	* decl.cc (get_symbol_decl): Mark register varibles DECL_REGISTER.
	Error when register variable declared thread-local or extern.
	* expr.cc (ExprVisitor::visit (IndexExp *)): Don't complain about
	marking register vectors as addressable in an ARRAY_REF.

libphobos/ChangeLog:

	* libdruntime/gcc/attributes.d (register): Define.

gcc/testsuite/ChangeLog:

	* gdc.dg/attr_register1.d: New test.
	* gdc.dg/attr_register2.d: New test.
	* gdc.dg/attr_register3.d: New test.

3 files changed, 88 insertions, 0 deletions

diff --git a/gcc/testsuite/gdc.dg/attr_register1.d b/gcc/testsuite/gdc.dg/attr_register1.d
new file mode 100644
index 0000000..01fc245
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/attr_register1.d
@@ -0,0 +1,55 @@
+// { dg-do compile }
+
+import gcc.attributes;
+
+@attribute("register", null) int var1; // { dg-error "attribute argument not a string constant" }
+
+@attribute("register", "") int var2; // { dg-error "register name not specified for .var2." }
+
+@attribute("register", "invalid") __gshared int var3; // { dg-error "invalid register name for .var3." }
+
+void f1(ref int r) { }
+
+void test1()
+{
+    @register("ref") int var6;
+    f1(var6); // { dg-error "address of explicit register variable .var6. requested" }
+}
+
+void f2(out int r) { }
+
+void test2()
+{
+    @register("out") int var7;
+    f2(var7); // { dg-error "address of explicit register variable .var7. requested" }
+}
+
+void f3(lazy int r) { }
+
+void test3()
+{
+    @register("lazy") int var8; // { dg-error "explicit register variable .var8. cannot be used in nested function" }
+    f3(var8);
+}
+
+void test4()
+{
+    @register("addr") int var9;
+    auto ptr3 = &var9; // { dg-error "address of explicit register variable .var9. requested" }
+}
+
+ref int test5()
+{
+    @register("refreturn") __gshared int var10; // { dg-error "invalid register name" }
+    return var10; // { dg-error "address of explicit register variable .var10. requested" }
+}
+
+auto test6()
+{
+    @register("closure") int var11; // { dg-error "explicit register variable .var11. cannot be used in nested function" }
+    int nested()
+    {
+        return var11;
+    }
+    return &nested;
+}
diff --git a/gcc/testsuite/gdc.dg/attr_register2.d b/gcc/testsuite/gdc.dg/attr_register2.d
new file mode 100644
index 0000000..9061a64
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/attr_register2.d
@@ -0,0 +1,11 @@
+// { dg-do compile  { target x86_64-*-* } }
+
+import gcc.attributes;
+
+@register("ebx") static int var1 = void; // { dg-error "explicit register variable .var1. declared thread local" }
+
+@register("ebx") extern int var2; // { dg-error "explicit register variable .var2. declared .extern." }
+
+@register("r12") __gshared int var3 = 0x2a; // { dg-error "global register variable has initial value" }
+
+@register("r12") __gshared int[256] var4 = void; // { dg-error "data type of .var4. isn.t suitable for a register" }
diff --git a/gcc/testsuite/gdc.dg/attr_register3.d b/gcc/testsuite/gdc.dg/attr_register3.d
new file mode 100644
index 0000000..706a399
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/attr_register3.d
@@ -0,0 +1,22 @@
+// { dg-do compile }
+// { dg-options "-Wall -O2 -fdump-tree-optimized" }
+
+import gcc.attributes;
+
+pragma(inline, true)
+void syscall()(int val)
+{
+    @register("4") int reg = val;
+    asm { "/* Some Code %0 */" :: "r" (reg); }
+}
+
+void do_syscalls()
+{
+    for (int s = 0; s < 2; s++)
+    {
+        syscall (0);
+        syscall (1);
+    }
+}
+
+// { dg-final { scan-tree-dump-times "reg = " 4 "optimized" } }