[docs] Document macOS as a supported host

macOS is a host for the ELF linker, not a Mach-O target. Document
.dylib plugin naming and DYLD_LIBRARY_PATH search.

Signed-off-by: Dhruv Menon <dhruvmenon1104@gmail.com>

Author: malto101

README.md

@@ -28,7 +28,11 @@ and is designed for easy addition of more backends.
 
 ## Building ELD and running tests
 
-ELD supports building and running tests on Linux and Windows utilizing LLVM.
+ELD supports building and running tests on Linux, Windows, and macOS (Darwin)
+utilizing LLVM. macOS is supported as a **host** (Apple Silicon and Intel);
+ELD still produces ELF images and does not link Mach-O. On macOS the linker
+binary is built natively for the host architecture (`arm64` or `x86_64`);
+universal binaries are not required.
 
 ELD depends on LLVM. You can build ELD either:
 - Integrated into an `llvm-project` build (recommended for running tests), or

docs/userguide/documentation/linker_faq.rst

@@ -3157,6 +3157,7 @@ Step 2
 Check to see if there any system environment variables set. Important variables to note are :-
 
 * LD_LIBRARY_PATH
+* DYLD_LIBRARY_PATH (macOS)
 * PATH (Windows)
 
 Remove the values set and see if the error disappears

docs/userguide/documentation/linker_plugins/linker_plugins.rst

@@ -235,8 +235,8 @@ For example::
      load.
    - Finds the library in the same search paths as if the library was passed
      as an input to the linker.
-   - Uses the name of the library without the lib prefix on Linux and without
-     the .so/.dll suffix on Linux/Windows, respectively
+   - Uses the name of the library without the lib prefix on Linux/macOS and
+     without the .so/.dll/.dylib suffix on Linux/Windows/macOS, respectively
 
 - **PluginName**
 
@@ -276,8 +276,8 @@ Plugin configuration file format should be as follows:::
 :code:`GlobalPlugins` list can specify any number of elements.
 :code:`Options` member is optional.
 
-:code:`Library` name should be specified without the lib prefix on Linux
-and without the .so/.dll suffix on Linux/Windows
+:code:`Library` name should be specified without the lib prefix on Linux/macOS
+and without the .so/.dll/.dylib suffix on Linux/Windows/macOS
 
 :code:`ControlMemorySizePlugin` and :code:`ControlFileSizePlugin` are output
 section plugins. Therefore, in the plugin configuration file, they need to be
@@ -340,6 +340,7 @@ The following steps describe how to develop a plugin:
     clang++ -c -I${HEXAGON_TOOLCHAIN_ROOT}/Tools/include ${SOURCE_BASENAME}.cpp -fPIC -stdlib=libc++
 
     # Link the plugin library with linker wrapper library, LW.
+    # Linux: lib${SOURCE_BASENAME}.so   macOS: lib${SOURCE_BASENAME}.dylib
     clang++ -shared ./${SOURCE_BASENAME}.o -L${HEXAGON_TOOLCHAIN_ROOT}/Tools/lib -lLW -stdlib=libc++ -o lib${SOURCE_BASENAME}.so
 
 7) Define :code:`RegisterAll` function in C linkage.
@@ -405,7 +406,9 @@ Linker performs the following operations to load, run and unload plugins.
 
 2) Loads all the specified plugin libraries.
 
-   #. To find plugin libraries, :code:`LD_LIBRARY_PATH` environment variable is used on unix environment.
+   #. To find plugin libraries, :code:`LD_LIBRARY_PATH` is used on Linux.
+      On macOS, :code:`DYLD_LIBRARY_PATH` is searched first, then
+      :code:`LD_LIBRARY_PATH`.
    #. Standard method for searching dynamic libraries is used in Windows.
 
 3) Calls :code:`RegisterAll` function from each plugin library. This function