lld-link: Let LLD_REPRODUCE control /linkrepro:, like in ld.lld

[thakis]

Summary

Also sync help texts for the option between elf and coff ports.

Decisions:

• Do this even if /lldignoreenv is passed. /linkrepro: does not affect the main output, and this makes the env var more convenient to use. (On the other hand, it's now possible to set this env var and forget about it, and all future builds in the same shell will be much slower. That's true for ld.lld, but posix shells have an easy way to set an env var for a single command; in cmd.exe this is not possible without contortions. Then again, lld-link runs in posix shells too.)

• Call the env var LLD_REPRODUCE like in ld.lld even though the flag is called /linkrepro: instead of --reproduce in lld-link.

[ruiu]

LGTM

lld/COFF/Driver.cpp

if (auto *arg = args.getLastArg(OPT_reproduce))
     return std::string(arg->getValue());
 
   if (auto *arg = args.getLastArg(OPT_linkrepro)) {
     SmallString<64> path = StringRef(arg->getValue());
     sys::path::append(path, "repro.tar");
     return std::string(path);
   }
 
+  // This is intentionally not guarded by OPT_lldignoreenv since writing
+  // a repro tar file doesn't affect the main output.
+  if (auto *path = getenv("LLD_REPRODUCE"))
+    return std::string(path);
+
   return None;
 }
 
 void LinkerDriver::link(ArrayRef<const char *> argsArr) {
   ScopedTimer rootTimer(Timer::root());
 
   // Needed for LTO.
   InitializeAllTargetInfos();

lld/COFF/Options.td

def functionpadmin_opt : P<"functionpadmin",
     "Prepares an image for hotpatching">;
 def guard   : P<"guard", "Control flow guard">;
 def heap    : P<"heap", "Size of the heap">;
 def ignore : P<"ignore", "Specify warning codes to ignore">;
 def implib  : P<"implib", "Import library name">;
 def lib : F<"lib">,
     HelpText<"Act like lib.exe; must be first argument if present">;
 def libpath : P<"libpath", "Additional library search path">;
-def linkrepro : P<"linkrepro",
-    "Dump linker invocation and input files for debugging">;
+def linkrepro : Joined<["/", "-", "/?", "-?"], "linkrepro:">,
+    MetaVarName<"directory">,
+    HelpText<"Write repro.tar containing inputs and command to reproduce link">;
 def lldignoreenv : F<"lldignoreenv">,
     HelpText<"Ignore environment variables like %LIB%">;
 def lldltocache : P<"lldltocache",
     "Path to ThinLTO cached object file directory">;
 def lldltocachepolicy : P<"lldltocachepolicy",
     "Pruning policy for the ThinLTO cache">;
 def lldsavetemps : F<"lldsavetemps">,
     HelpText<"Save temporary files instead of deleting them">;

 def driver_uponly_wdm : F<"driver:uponly,wdm">;
 def nodefaultlib_all : F<"nodefaultlib">,
     HelpText<"Remove all default libraries">;
 def noentry : F<"noentry">,
     HelpText<"Don't add reference to DllMainCRTStartup; only valid with /dll">;
 def profile : F<"profile">;
 def repro : F<"Brepro">,
     HelpText<"Use a hash of the executable as the PE header timestamp">;
-def reproduce : P<"reproduce",
-    "Dump linker invocation and input files for debugging">;
+def reproduce : Joined<["/", "-", "/?", "-?"], "reproduce:">,
+    MetaVarName<"filename">,
+    HelpText<"Write tar file containing inputs and command to reproduce link">;
 def swaprun : P<"swaprun",
   "Comma-separated list of 'cd' or 'net'">;
 def swaprun_cd : F<"swaprun:cd">, Alias<swaprun>, AliasArgs<["cd"]>,
   HelpText<"Make loader run output binary from swap instead of from CD">;
 def swaprun_net : F<"swaprun:net">, Alias<swaprun>, AliasArgs<["net"]>,
   HelpText<"Make loader run output binary from swap instead of from network">;
 def verbose : F<"verbose">;
 def wholearchive_flag : F<"wholearchive">,

 
 // /?? and -?? must be before /? and -? to not confuse lib/Options.
 def help_q : Flag<["/??", "-??", "/?", "-?"], "">, Alias<help>;
 
 // LLD extensions
 defm auto_import : B_priv<"auto-import">;
 defm runtime_pseudo_reloc : B_priv<"runtime-pseudo-reloc">;
 def end_lib : F<"end-lib">,
-  HelpText<"Ends group of objects treated as if they were in a library">;
+  HelpText<"End group of objects treated as if they were in a library">;
 def exclude_all_symbols : F<"exclude-all-symbols">;
 def export_all_symbols : F<"export-all-symbols">;
 defm demangle : B<"demangle",
     "Demangle symbols in output (default)",
     "Do not demangle symbols in output">;
 def include_optional : Joined<["/", "-", "/?", "-?"], "includeoptional:">,
     HelpText<"Add symbol as undefined, but allow it to remain undefined">;
 def kill_at : F<"kill-at">;
 def lldmingw : F<"lldmingw">;
 def noseh : F<"noseh">;
 def osversion : P_priv<"osversion">;
 def output_def : Joined<["/", "-", "/?", "-?"], "output-def:">;
 def pdb_source_path : P<"pdbsourcepath",
     "Base path used to make relative source file path absolute in PDB">;
 def rsp_quoting : Joined<["--"], "rsp-quoting=">,
   HelpText<"Quoting style for response files, 'windows' (default) or 'posix'">;
 def start_lib : F<"start-lib">,
-  HelpText<"Starts group of objects treated as if they were in a library">;
+  HelpText<"Start group of objects treated as if they were in a library">;
 def thinlto_emit_imports_files :
     F<"thinlto-emit-imports-files">,
     HelpText<"Emit .imports files with -thinlto-index-only">;
 def thinlto_index_only :
     F<"thinlto-index-only">,
     HelpText<"Instead of linking, emit ThinLTO index files">;
 def thinlto_index_only_arg : P<
     "thinlto-index-only",

lld/ELF/Options.td

def pop_state: F<"pop-state">,
   HelpText<"Undo the effect of -push-state">;
 
 def push_state: F<"push-state">,
   HelpText<"Save the current state of -as-needed, -static and -whole-archive">;
 
 def print_map: F<"print-map">,
   HelpText<"Print a link map to the standard output">;
 
-defm reproduce: Eq<"reproduce", "Write a tar file containing input files and command line options to reproduce link">;
+defm reproduce:
+  Eq<"reproduce",
+     "Write tar file containing inputs and command to reproduce link">;
 
 defm rosegment: BB<"rosegment",
   "Put read-only non-executable sections in their own segment (default)",
   "Do not put read-only non-executable sections in their own segment">;
 
 defm rpath: Eq<"rpath", "Add a DT_RUNPATH to the output">;
 
 def relocatable: F<"relocatable">, HelpText<"Create relocatable object file">;

lld/test/COFF/linkrepro.test

 # REQUIRES: x86, shell
 
 # RUN: rm -rf %t.dir
-# RUN: mkdir -p %t.dir/build1 %t.dir/build2 %t.dir/build3
+# RUN: mkdir -p %t.dir/build1 %t.dir/build2 %t.dir/build3 %t.dir/build4
 # RUN: yaml2obj %p/Inputs/hello32.yaml -o %t.obj
 
 # RUN: cd %t.dir/build1
 # RUN: lld-link %t.obj %p/Inputs/std32.lib /subsystem:console \
 # RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RUN: cd %t.dir/build1
 # RUN: lld-link %t.obj %p/Inputs/std32.lib /subsystem:console \
 # RUN:   /entry:main@0 /reproduce:repro2.tar /out:%t.exe
 # RUN: tar xf repro2.tar
 # RUN: diff %t.obj repro2/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro2/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro2/response.txt
 
 # RUN: cd %t.dir/build2
+# RUN: env LLD_REPRODUCE=repro.tar lld-link %t.obj %p/Inputs/std32.lib \
+# RUN:    /subsystem:console /entry:main@0 /out:%t.exe
+# RUN: tar xf repro.tar
+# RUN: diff %t.obj repro/%:t.obj
+# RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
+# RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
+
+# RUN: cd %t.dir/build3
 # RUN: lld-link %t.obj /libpath:%p/Inputs /defaultlib:std32 /subsystem:console \
 # RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
-# RUN: cd %t.dir/build3
+# RUN: cd %t.dir/build4
 # RUN: env LIB=%p/Inputs lld-link %t.obj /defaultlib:std32 /subsystem:console \
 # RUN:   /entry:main@0 /linkrepro:. /out:%t.exe
 # RUN: tar xf repro.tar
 # RUN: diff %t.obj repro/%:t.obj
 # RUN: diff %p/Inputs/std32.lib repro/%:p/Inputs/std32.lib
 # RUN: FileCheck %s --check-prefix=RSP < repro/response.txt
 
 # RSP: /subsystem:console
 # RSP: /entry:main@0
 # RSP-NOT: /linkrepro:
 # RSP: /out:
 # RSP: linkrepro.test.tmp.obj
 # RSP-NOT: defaultlib
 # RSP: std32.lib