[lld] [LLD] [MinGW] Handle the --dll option (PR #68575)

[Martin Storsjö via llvm-commits]

https://github.com/mstorsjo created https://github.com/llvm/llvm-project/pull/68575

Treat this as an alias for the --shared option.

In practice in GNU ld, they aren't exact aliases but there are small subtle differences in what happens and what doesn't, when they are set, but those differences are probably not intended by users who might be using the --dll option (which gets passed by -mdll in the compiler driver), and the differences are within the area where small details differ between LLD and GNU ld anyway.

>From 7686d9a7c0bcdaf63fcb4207505c13a12a97a526 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin at martin.st>
Date: Mon, 9 Oct 2023 14:01:26 +0300
Subject: [PATCH] [LLD] [MinGW] Handle the --dll option

Treat this as an alias for the --shared option.

In practice in GNU ld, they aren't exact aliases but there are
small subtle differences in what happens and what doesn't, when they
are set, but those differences are probably not intended by users
who might be using the --dll option (which gets passed by -mdll in
the compiler driver), and the differences are within the area where
small details differ between LLD and GNU ld anyway.
---
 lld/MinGW/Options.td       | 1 +
 lld/test/MinGW/driver.test | 1 +
 2 files changed, 2 insertions(+)

diff --git a/lld/MinGW/Options.td b/lld/MinGW/Options.td
index f59bd5bc38a8db8..fa4c4ecc75d6543 100644
--- a/lld/MinGW/Options.td
+++ b/lld/MinGW/Options.td
@@ -203,6 +203,7 @@ def alias_Bdynamic_dy: Flag<["-"], "dy">, Alias<Bdynamic>;
 def alias_Bstatic_dn: Flag<["-"], "dn">, Alias<Bstatic>;
 def alias_Bstatic_non_shared: Flag<["-"], "non_shared">, Alias<Bstatic>;
 def alias_Bstatic_static: Flag<["-"], "static">, Alias<Bstatic>;
+def alias_dll: F<"dll">, Alias<shared>;
 def alias_entry_e: JoinedOrSeparate<["-"], "e">, Alias<entry>;
 def alias_no_dynamicbase: F<"no-dynamicbase">, Alias<disable_dynamicbase>;
 def alias_strip_s: Flag<["-"], "s">, Alias<strip_all>;
diff --git a/lld/test/MinGW/driver.test b/lld/test/MinGW/driver.test
index 2893f8c66fd122c..1fdd494754af4bf 100644
--- a/lld/test/MinGW/driver.test
+++ b/lld/test/MinGW/driver.test
@@ -27,6 +27,7 @@ ARM64-SAME: foo.o
 
 RUN: ld.lld -### foo.o -m i386pep -shared 2>&1 | FileCheck -check-prefix=SHARED %s
 RUN: ld.lld -### foo.o -m i386pep --shared 2>&1 | FileCheck -check-prefix=SHARED %s
+RUN: ld.lld -### foo.o -m i386pep --dll 2>&1 | FileCheck -check-prefix=SHARED %s
 SHARED:      -out:a.dll
 SHARED-SAME: -dll