[PATCH] D91583: [lld] Allow --export-dynamic to override --lto-whole-program-visibility

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson created this revision.
tejohnson added a reviewer: MaskRay.
Herald added subscribers: dang, steven_wu, hiraditya, arichardson, inglorion, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.
tejohnson requested review of this revision.

Adds a version of --lto-whole-program-visibility that takes a parameter,
including a new 'noexportdynamic', in which case --lto-whole-program-visibility
is not enabled when --export-dynamic is specified. Use of --export-dynamic
suggests that there may not in fact be whole program visibility, because
symbols become available externally, enabling e.g. virtual function
overrides not seen by the LTO unit. Adding this support simplifies use
of --lto-whole-program-visibility in contexts where static linking is
typically the case, but where some binaries will use --export-dynamic to
enable dlopen.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D91583

Files:
  lld/ELF/Driver.cpp
  lld/ELF/Options.td
  lld/test/ELF/lto/devirt_vcall_vis_public.ll


Index: lld/test/ELF/lto/devirt_vcall_vis_public.ll
===================================================================
--- lld/test/ELF/lto/devirt_vcall_vis_public.ll
+++ lld/test/ELF/lto/devirt_vcall_vis_public.ll
@@ -7,6 +7,15 @@
 ; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility \
 ; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
 ; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+; Try again with explicit "on"
+; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility=on \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
+; Try again with "noexportdynamic" and use -u instead of --export-dynamic
+; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility=noexportdynamic \
+; RUN: 	 -mllvm -pass-remarks=. -u _start -u _ZTV1B -u _ZTV1C -u _ZTV1D \
+; RUN:	  2>&1 | FileCheck %s --check-prefix=REMARK
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-IR
 
 ; Hybrid WPD
 ; Generate split module with summary for hybrid Thin/Regular LTO WPD.
@@ -31,6 +40,14 @@
 ; RUN: ld.lld %t2.o -o %t3 -save-temps \
 ; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
 ; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+; Try again with explicit "off"
+; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility=off \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
+; Try again with "noexportdynamic"
+; RUN: ld.lld %t2.o -o %t3 -save-temps --lto-whole-program-visibility=noexportdynamic \
+; RUN: 	 -mllvm -pass-remarks=. --export-dynamic 2>&1 | FileCheck %s --implicit-check-not single-impl --allow-empty
+; RUN: llvm-dis %t2.o.4.opt.bc -o - | FileCheck %s --check-prefix=CHECK-NODEVIRT-IR
 
 ; Hybrid WPD
 ; RUN: ld.lld %t.o -o %t3 -save-temps \
Index: lld/ELF/Options.td
===================================================================
--- lld/ELF/Options.td
+++ lld/ELF/Options.td
@@ -542,8 +542,12 @@
 def lto_obj_path_eq: JJ<"lto-obj-path=">;
 def lto_sample_profile: JJ<"lto-sample-profile=">,
   HelpText<"Sample profile file path">;
-def lto_whole_program_visibility: FF<"lto-whole-program-visibility">,
-  HelpText<"Asserts that the LTO link has whole program visibility">;
+def lto_whole_program_visibility: FF<"lto-whole-program-visibility">;
+def lto_whole_program_visibility_eq: JJ<"lto-whole-program-visibility=">,
+  HelpText<"Asserts that the LTO link has whole program visibility. "
+	  "If specified without any argument, defaults to 'on'. "
+	  "If 'noexportdynamic' then on unless --export-dynamic also specified.">,
+  MetaVarName<"[off,noexportdynamic,on]">;
 def disable_verify: F<"disable-verify">;
 defm mllvm: Eq<"mllvm", "Additional arguments to forward to LLVM's option processing">;
 def opt_remarks_filename: Separate<["--"], "opt-remarks-filename">,
Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -845,6 +845,24 @@
   return true;
 }
 
+static bool getLtoWholeProgramVisibility(opt::InputArgList &args) {
+  auto *Arg = args.getLastArg(OPT_lto_whole_program_visibility,
+                              OPT_lto_whole_program_visibility_eq);
+  if (!Arg)
+    return false;
+  if (Arg->getOption().getID() == OPT_lto_whole_program_visibility)
+    return true;
+  StringRef s = Arg->getValue();
+  if (s == "off")
+    return false;
+  else if (s == "on")
+    return true;
+  else if (s == "noexportdynamic")
+    return !(args.hasFlag(OPT_export_dynamic, OPT_no_export_dynamic, false));
+  error("unknown --lto-whole-program-visibility: " + s);
+  return false;
+}
+
 static StringRef getAliasSpelling(opt::Arg *arg) {
   if (const opt::Arg *alias = arg->getAlias())
     return alias->getSpelling();
@@ -974,8 +992,7 @@
   config->ltoEmitAsm = args.hasArg(OPT_lto_emit_asm);
   config->ltoNewPassManager = args.hasArg(OPT_lto_new_pass_manager);
   config->ltoNewPmPasses = args.getLastArgValue(OPT_lto_newpm_passes);
-  config->ltoWholeProgramVisibility =
-      args.hasArg(OPT_lto_whole_program_visibility);
+  config->ltoWholeProgramVisibility = getLtoWholeProgramVisibility(args);
   config->ltoo = args::getInteger(args, OPT_lto_O, 2);
   config->ltoObjPath = args.getLastArgValue(OPT_lto_obj_path_eq);
   config->ltoPartitions = args::getInteger(args, OPT_lto_partitions, 1);


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