[LLD] [MinGW] Add an lld specific option for requesting to delay load libraries

[mstorsjo]

Summary

With GNU tools, delayload is handled completely differently. (One creates a specific delayload import library using dlltool and then links against it instead of the normal import library.)

Instead of requiring using -Xlink=-delayload:lib.dll, we can provide an lld specific option for this.

@jacek - If this one lands, do you need it in the 9.x release branch? (I might do an llvm-mingw release from that point release, but then move on back to latest trunk when there's other changes I need from there.)

[ruiu]

LGTM

[jacek]

Thanks for doing that!

My patch for Wine using delayload is still under review, but I think Wine will better use -Xlink syntax to cover existing LLD versions for now anyway. Mozilla may use it right away, since they target their own toolchain build anyway: https://bugzilla.mozilla.org/show_bug.cgi?id=1570597

[mstorsjo]

In D65728#1617032, @jacek wrote:

My patch for Wine using delayload is still under review, but I think Wine will better use -Xlink syntax to cover existing LLD versions for now anyway. Mozilla may use it right away, since they target their own toolchain build anyway: https://bugzilla.mozilla.org/show_bug.cgi?id=1570597

Ok.

Despite this - @hans - do you think this one would be an acceptable backport? (Sorry for flooding you with all these, but I was a bit busy before the branch...)

[hans]

In D65728#1617380, @mstorsjo wrote:

In D65728#1617032, @jacek wrote:

My patch for Wine using delayload is still under review, but I think Wine will better use -Xlink syntax to cover existing LLD versions for now anyway. Mozilla may use it right away, since they target their own toolchain build anyway: https://bugzilla.mozilla.org/show_bug.cgi?id=1570597

Ok.

Despite this - @hans - do you think this one would be an acceptable backport? (Sorry for flooding you with all these, but I was a bit busy before the branch...)

Yes, sounds good to me. Merged in r368134.

lld/trunk/MinGW/Driver.cpp

if (args.getLastArgValue(OPT_m) == "i386pe")
     add("-alternatename:__image_base__=___ImageBase");
   else
     add("-alternatename:__image_base__=__ImageBase");
 
   for (auto *a : args.filtered(OPT_require_defined))
     add("-include:" + StringRef(a->getValue()));
   for (auto *a : args.filtered(OPT_undefined))
     add("-includeoptional:" + StringRef(a->getValue()));
+  for (auto *a : args.filtered(OPT_delayload))
+    add("-delayload:" + StringRef(a->getValue()));
 
   std::vector<StringRef> searchPaths;
   for (auto *a : args.filtered(OPT_L)) {
     searchPaths.push_back(a->getValue());
     add("-libpath:" + StringRef(a->getValue()));
   }
 
   StringRef prefix = "";

lld/trunk/MinGW/Options.td

 def require_defined: S<"require-defined">,
     HelpText<"Force symbol to be added to symbol table as an undefined one">;
 def require_defined_eq: J<"require-defined=">, Alias<require_defined>;
 
 // LLD specific options
 def _HASH_HASH_HASH : Flag<["-"], "###">,
     HelpText<"Print (but do not run) the commands to run for this compilation">;
 def appcontainer: F<"appcontainer">, HelpText<"Set the appcontainer flag in the executable">;
+def delayload: S<"delayload">, HelpText<"DLL to load only on demand">;
+def delayload_eq: J<"delayload=">, Alias<delayload>;
 def mllvm: S<"mllvm">;
 def pdb: S<"pdb">, HelpText<"Output PDB debug info file, chosen implicitly if the argument is empty">;
 def pdb_eq: J<"pdb=">, Alias<pdb>;
 def Xlink : J<"Xlink=">, MetaVarName<"<arg>">,
     HelpText<"Pass <arg> to the COFF linker">;
 
 // Alias
 def alias_entry_e: JoinedOrSeparate<["-"], "e">, Alias<entry>;

lld/trunk/test/MinGW/driver.test

 # RUN: ld.lld -m i386pep --version 2>&1 | FileCheck -check-prefix=VERSION %s
 # RUN: ld.lld -m i386pep -v 2>&1 | FileCheck -check-prefix=VERSION %s
 # RUN: not ld.lld -m i386pep -v xyz 2>&1 | FileCheck -check-prefix=VERSION %s
 # VERSION: LLD {{.*}} (compatible with GNU linkers)
 
 # RUN: ld.lld -m i386pep --help 2>&1 | FileCheck -check-prefix=HELP %s
 # HELP: USAGE:
 # HELP: --enable-auto-import
+
+RUN: ld.lld -### -m i386pep foo.o -delayload user32.dll --delayload shell32.dll | FileCheck -check-prefix DELAYLOAD %s
+RUN: ld.lld -### -m i386pep foo.o -delayload=user32.dll --delayload=shell32.dll | FileCheck -check-prefix DELAYLOAD %s
+DELAYLOAD: -delayload:user32.dll -delayload:shell32.dll