From 5d7947e6d919418765b02c6ad327bd7d0bde586d Mon Sep 17 00:00:00 2001
From: Pat Bernardi <bernardi@adacore.com>
Date: Tue, 9 Jul 2024 10:38:56 -0400
Subject: [PATCH] Treat loaders differently for OS targets

As background, OS targets use OS provided linker scripts rather than scripts
provided by the runtime. Instead of resorting to external runtime.xml files
to  exclude references to these scripts,  target.py is enhanced to not
generate references these bare-metal specific loaders and linker scripts
through a new Target property is_os_target. This makes it easier to maintain
OS target's compiler and linker switches in a single file in bb-runtimes.
The loaders property is also repurposed for OS targets to accommodate
different link time scenarios.

Issue: #70
---
 support/bsp_sources/target.py | 71 +++++++++++++++++++----------------
 1 file changed, 38 insertions(+), 33 deletions(-)

diff --git a/support/bsp_sources/target.py b/support/bsp_sources/target.py
index 034a41f7..a7de8b6b 100644
--- a/support/bsp_sources/target.py
+++ b/support/bsp_sources/target.py
@@ -286,9 +286,14 @@ def dump_runtime_xml(self, rts_name, rts):
         ret += "  <configuration>\n"
         ret += "    <config><![CDATA[\n"
 
-        # Add LOADER selection for bare-metal targets
-
-        if not self.is_os_target:
+        # Add LOADER selection. For bare metal targets we always have loaders
+        # (the linker scripts used to load the program to memory). OS targets
+        # may or may not use loaders. If they do, it may be used to influence
+        # the linking behaviour rather than purely specifying linker scripts.
+        if self.is_os_target:
+            if self.loaders is not None:
+                loaders = list(self.loaders)
+        else:
             if self.loaders is not None:
                 # Add USER loader so users can always specify their own linker
                 # script. To ensure the USER loader is always used for this
@@ -307,6 +312,7 @@ def dump_runtime_xml(self, rts_name, rts):
                 else:
                     loaders = ["USER"]
 
+        if self.loaders is not None:
             ret += '   type Loaders is ("%s");\n' % '", "'.join(loaders)
             ret += '   Loader : Loaders := external("LOADER", "%s");\n\n' % loaders[0]
 
@@ -412,42 +418,41 @@ def dump_runtime_xml(self, rts_name, rts):
         indent = 6
         blank = indent * " "
 
-        # Add LOADER specific options (only needed for bare-metal runtimes)
-        if not self.is_os_target:
-            if loaders is not None:
-                ret += "\n" + blank
-                ret += "case Loader is\n"
+        # Add LOADER specific options
+        if self.loaders is not None:
+            ret += "\n" + blank
+            ret += "case Loader is\n"
+            indent += 3
+            blank = indent * " "
+
+            for loader in loaders:
+                ret += blank
+                ret += 'when "%s" =>\n' % loader
+                if loader == "USER":
+                    continue
                 indent += 3
                 blank = indent * " "
 
-                for loader in loaders:
+                switches = []
+                for val in self.ld_scripts:
+                    if val.loaders is None or loader in val.loaders:
+                        switches.append('"-T", "%s"' % val.name)
+                for sw in self.ld_switches:
+                    if is_string(sw["loader"]) and sw["loader"] == loader:
+                        switches.append('"%s"' % sw["switch"])
+                    if isinstance(sw["loader"], list) and loader in sw["loader"]:
+                        switches.append('"%s"' % sw["switch"])
+                if len(switches) > 0:
                     ret += blank
-                    ret += 'when "%s" =>\n' % loader
-                    if loader == "USER":
-                        continue
-                    indent += 3
-                    blank = indent * " "
-
-                    switches = []
-                    for val in self.ld_scripts:
-                        if val.loaders is None or loader in val.loaders:
-                            switches.append('"-T", "%s"' % val.name)
-                    for sw in self.ld_switches:
-                        if is_string(sw["loader"]) and sw["loader"] == loader:
-                            switches.append('"%s"' % sw["switch"])
-                        if isinstance(sw["loader"], list) and loader in sw["loader"]:
-                            switches.append('"%s"' % sw["switch"])
-                    if len(switches) > 0:
-                        ret += blank
-                        ret += "for Required_Switches use Linker'Required_Switches"
-                        ret += " &\n" + blank + "  "
-                        ret += "(%s);\n" % (",\n   " + blank).join(switches)
-                    indent -= 3
-                    blank = indent * " "
-
+                    ret += "for Required_Switches use Linker'Required_Switches"
+                    ret += " &\n" + blank + "  "
+                    ret += "(%s);\n" % (",\n   " + blank).join(switches)
                 indent -= 3
                 blank = indent * " "
-                ret += "%send case;\n" % blank
+
+            indent -= 3
+            blank = indent * " "
+            ret += "%send case;\n" % blank
 
         ret += (
             "   end Linker;\n"