[LLD] [MinGW] Implement the --file-alignment and --section-alignment options

[mstorsjo]

@amccarth Any opinion on this one? It's a pretty straightforward mapping of these options from GNU ld format to what lld-link internally uses. (I'd like to get it in before the branch if possible - although it's probably also possible to ask to get it cherrypicked even a few days after the branch...)

[amccarth]

Sorry, I thought I had LGTM'ed yesterday. I guess the Submit didn't take.

lld/MinGW/Driver.cpp

bool mingw::link(ArrayRef<const char *> argsArr, bool canExitEarly,
   if (auto *a = args.getLastArg(OPT_image_base))
     add("-base:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_map))
     add("-lldmap:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_reproduce))
     add("-reproduce:" + StringRef(a->getValue()));
   if (auto *a = args.getLastArg(OPT_thinlto_cache_dir))
     add("-lldltocache:" + StringRef(a->getValue()));
+  if (auto *a = args.getLastArg(OPT_file_alignment))
+    add("-filealign:" + StringRef(a->getValue()));
+  if (auto *a = args.getLastArg(OPT_section_alignment))
+    add("-align:" + StringRef(a->getValue()));
 
   if (auto *a = args.getLastArg(OPT_o))
     add("-out:" + StringRef(a->getValue()));
   else if (args.hasArg(OPT_shared))
     add("-out:a.dll");
   else
     add("-out:a.exe");
 

lld/MinGW/Options.td

def enable_auto_import: F<"enable-auto-import">,
     HelpText<"Automatically import data symbols from other DLLs where needed">;
 def enable_runtime_pseudo_reloc: F<"enable-runtime-pseudo-reloc">,
     HelpText<"Allow automatic imports that require runtime fixups">;
 defm entry: Eq<"entry", "Name of entry point symbol">, MetaVarName<"<entry>">;
 def exclude_all_symbols: F<"exclude-all-symbols">,
     HelpText<"Don't automatically export any symbols">;
 def export_all_symbols: F<"export-all-symbols">,
     HelpText<"Export all symbols even if a def file or dllexport attributes are used">;
+defm file_alignment: Eq<"file-alignment", "Set file alignment">;
 def gc_sections: F<"gc-sections">, HelpText<"Remove unused sections">;
 def help: F<"help">, HelpText<"Print option help">;
 def icf: J<"icf=">, HelpText<"Identical code folding">;
 def image_base: S<"image-base">, HelpText<"Base address of the program">;
 def insert_timestamp: F<"insert-timestamp">,
     HelpText<"Include PE header timestamp">;
 def kill_at: F<"kill-at">, HelpText<"Remove @n from exported symbols">;
 def l: JoinedOrSeparate<["-"], "l">, MetaVarName<"<libName>">,
def no_whole_archive: F<"no-whole-archive">,
     HelpText<"No longer include all object files for following archives">;
 def large_address_aware: Flag<["--"], "large-address-aware">,
     HelpText<"Enable large addresses">;
 def no_gc_sections: F<"no-gc-sections">, HelpText<"Don't remove unused sections">;
 def o: JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
   HelpText<"Path to file to write output">;
 defm out_implib: Eq<"out-implib", "Import library name">;
 defm output_def: Eq<"output-def", "Output def file">;
+defm section_alignment: Eq<"section-alignment", "Set section alignment">;
 def shared: F<"shared">, HelpText<"Build a shared object">;
 defm subs: Eq<"subsystem", "Specify subsystem">;
 def stack: S<"stack">;
 def strip_all: F<"strip-all">,
     HelpText<"Omit all symbol information from the output binary">;
 def strip_debug: F<"strip-debug">,
     HelpText<"Omit all debug information, but keep symbol information">;
 defm reproduce: Eq<"reproduce", "Write a tar file containing input files and command line options to reproduce link">;

lld/test/MinGW/driver.test

 ENABLE_RUNTIME_PSEUDO_RELOC: -runtime-pseudo-reloc{{ }}
 
 RUN: ld.lld -### -m i386pep foo.o --disable-runtime-pseudo-reloc | FileCheck -check-prefix DISABLE_RUNTIME_PSEUDO_RELOC %s
 RUN: ld.lld -### -m i386pep foo.o -disable-runtime-pseudo-reloc | FileCheck -check-prefix DISABLE_RUNTIME_PSEUDO_RELOC %s
 DISABLE_RUNTIME_PSEUDO_RELOC: -runtime-pseudo-reloc:no
 
 RUN: ld.lld -### foo.o -m i386pe --thinlto-cache-dir=_foo | FileCheck -check-prefix=THINLTO_CACHEDIR %s
 THINLTO_CACHEDIR: -lldltocache:_foo
+
+RUN: ld.lld -### -m i386pep foo.o --file-alignment 0x1000 | FileCheck -check-prefix FILEALIGN %s
+RUN: ld.lld -### -m i386pep foo.o -file-alignment 0x1000 | FileCheck -check-prefix FILEALIGN %s
+RUN: ld.lld -### -m i386pep foo.o --file-alignment=0x1000 | FileCheck -check-prefix FILEALIGN %s
+RUN: ld.lld -### -m i386pep foo.o -file-alignment=0x1000 | FileCheck -check-prefix FILEALIGN %s
+FILEALIGN: -filealign:0x1000
+
+RUN: ld.lld -### -m i386pep foo.o --section-alignment 0x2000 | FileCheck -check-prefix ALIGN %s
+RUN: ld.lld -### -m i386pep foo.o -section-alignment 0x2000 | FileCheck -check-prefix ALIGN %s
+RUN: ld.lld -### -m i386pep foo.o --section-alignment=0x2000 | FileCheck -check-prefix ALIGN %s
+RUN: ld.lld -### -m i386pep foo.o -section-alignment=0x2000 | FileCheck -check-prefix ALIGN %s
+ALIGN: -align:0x2000