gn build: Create regular archives for the sanitizer runtimes.

[pcc]

Summary

We'll need to do this eventually if we create an installable package.
For now, this lets me use the archives to build Android, whose build
system wants to copy the archives to another location.

[thakis]

lgtm if mixing non-dash style flags (rcsD) with -T works in both gnu ar and llvm-ar.

llvm/utils/gn/build/BUILD.gn

139

Want to add a comment like "to make an archive not thin, you need to remove this config and set complete-static_lib"?

[pcc]

In D57607#1381291, @thakis wrote:

lgtm if mixing non-dash style flags (rcsD) with -T works in both gnu ar and llvm-ar.

Seems to work here.

llvm/utils/gn/build/BUILD.gn

 config("no_rtti") {
   if (current_os == "win") {
     cflags_cc = [ "/GR-" ]
   } else {
     cflags_cc = [ "-fno-rtti" ]
   }
 }
 
+config("thin_archive") {
+  if (current_os != "win" && current_os != "mac") {
+    arflags = [ "-T" ]
+  }
+}
+
 config("llvm_code") {
   include_dirs = [
     "//llvm/include",
     "$root_gen_dir/llvm/include",
   ]
 }
 
 config("lld_code") {

llvm/utils/gn/build/BUILDCONFIG.gn

 # All targets will get this list of configs by default.
 # Targets can opt out of a config by removing it from their local configs list.
 # If you're adding global flags and don't need targets to be able to opt out,
 # add the flags to compiler_defaults, not to a new config.
 shared_binary_target_configs = [
   "//llvm/utils/gn/build:compiler_defaults",
   "//llvm/utils/gn/build:llvm_code",
   "//llvm/utils/gn/build:no_rtti",
+  "//llvm/utils/gn/build:thin_archive",
   "//llvm/utils/gn/build:warn_covered_switch_default",
 ]
 
 # Apply that default list to the binary target types.
 set_defaults("executable") {
   configs = shared_binary_target_configs
 }
 set_defaults("loadable_module") {

llvm/utils/gn/build/toolchain/BUILD.gn

toolchain(target_name) {
 
     tool("alink") {
       if (current_os == "mac") {
         command = "libtool -static -no_warning_for_no_symbols {{arflags}} -o {{output}} {{inputs}}"
       } else {
         # Remove the output file first so that ar doesn't try to modify the
         # existing file.
         command =
-            "rm -f {{output}} && $ar rcsDT {{arflags}} {{output}} {{inputs}}"
+            "rm -f {{output}} && $ar rcsD {{arflags}} {{output}} {{inputs}}"
       }
       description = "AR {{output}}"
       outputs = [
         "{{output_dir}}/{{target_output_name}}.a",
       ]
       output_prefix = "lib"
       default_output_dir = "{{root_out_dir}}/lib"
     }

llvm/utils/gn/secondary/compiler-rt/lib/hwasan/BUILD.gn

sources = [
     "hwasan_new_delete.cc",
   ]
 }
 
 static_library("hwasan") {
   output_dir = crt_current_out_dir
   output_name = "clang_rt.hwasan-$crt_current_target"
   complete_static_lib = true
-  configs -= [ "//llvm/utils/gn/build:llvm_code" ]
+  configs -= [
+    "//llvm/utils/gn/build:llvm_code",
+    "//llvm/utils/gn/build:thin_archive",
+  ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
   deps = [
     ":sources",
   ]
 }
 
 static_library("hwasan_cxx") {
   output_dir = crt_current_out_dir
   output_name = "clang_rt.hwasan_cxx-$crt_current_target"
   complete_static_lib = true
-  configs -= [ "//llvm/utils/gn/build:llvm_code" ]
+  configs -= [
+    "//llvm/utils/gn/build:llvm_code",
+    "//llvm/utils/gn/build:thin_archive",
+  ]
   configs += [ "//llvm/utils/gn/build:crt_code" ]
   deps = [
     ":cxx_sources",
   ]
 }
 
 shared_library("hwasan_shared") {
   output_dir = crt_current_out_dir