Implement --{push,pop}-state.

--push-state implemented in this patch saves the states of --as-needed,
--whole-archive and --static. It saves less number of flags than GNU linkers.
Since even GNU linkers save different flags, no one seems to care about the
details. In this patch, I tried to save the minimal number of flags to not
complicate the implementation and the siutation.

I'm not personally happy about adding the --{push,pop}-state flags though.
That options seem too hacky to me. However, gcc started using the options
since GCC 8 when GNU ld is available at the build time. Therefore, lld
is no longer a drop-in replacmenet for GNU linker for that machine
without supporting the flags.

Fixes https://bugs.llvm.org/show_bug.cgi?id=34567

Differential Revision: https://reviews.llvm.org/D47542

llvm-svn: 333646

4 files changed, 66 insertions, 0 deletions

diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index d196bb167ec..e6eba274e02 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -940,6 +940,10 @@ static bool getBinaryOption(StringRef S) {
 }
 
 void LinkerDriver::createFiles(opt::InputArgList &Args) {
+  // For --{push,pop}-state.
+  std::vector<std::tuple<bool, bool, bool>> Stack;
+
+  // Iterate over argv to process input files and positional arguments.
   for (auto *Arg : Args) {
     switch (Arg->getOption().getUnaliasedOption().getID()) {
     case OPT_library:
@@ -1016,6 +1020,17 @@ void LinkerDriver::createFiles(opt::InputArgList &Args) {
       InputFile::IsInGroup = false;
       ++InputFile::NextGroupId;
       break;
+    case OPT_push_state:
+      Stack.push_back({Config->AsNeeded, Config->Static, InWholeArchive});
+      break;
+    case OPT_pop_state:
+      if (Stack.empty()) {
+        error("unbalanced --push-state/--pop-state");
+        break;
+      }
+      std::tie(Config->AsNeeded, Config->Static, InWholeArchive) = Stack.back();
+      Stack.pop_back();
+      break;
     }
   }
 
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 422784d87d2..c8a1260cfb0 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -244,6 +244,12 @@ defm print_icf_sections: B<"print-icf-sections",
     "List identical folded sections",
     "Do not list identical folded sections (default)">;
 
+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">;
 
diff --git a/lld/docs/ld.lld.1 b/lld/docs/ld.lld.1
index 95d9750cca6..7f3a747bbbd 100644
--- a/lld/docs/ld.lld.1
+++ b/lld/docs/ld.lld.1
@@ -289,6 +289,15 @@ Create a position independent executable.
 List removed unused sections.
 .It Fl -print-map
 Print a link map to the standard output.
+.It Fl -push-state
+Save the current state of
+.Fl -as-needed ,
+.Fl -static ,
+and
+.Fl -while-archive.
+.It Fl -pop-state
+Undo the effect of
+.Fl -push-state.
 .It Fl -relocatable
 Create relocatable object file.
 .It Fl -reproduce Ns = Ns Ar value
diff --git a/lld/test/ELF/push-state.s b/lld/test/ELF/push-state.s
new file mode 100644
index 00000000000..5a01cd2eeed
--- /dev/null
+++ b/lld/test/ELF/push-state.s
@@ -0,0 +1,36 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
+// RUN:   %p/Inputs/whole-archive.s -o %t2.o
+// RUN: rm -f %t.a
+// RUN: llvm-ar rcs %t.a %t2.o
+
+// RUN: ld.lld -o %t.exe -push-state -whole-archive %t.a %t1.o -M | \
+// RUN:   FileCheck -check-prefix=WHOLE %s
+// WHOLE: _bar
+
+// RUN: ld.lld -o %t.exe -push-state -whole-archive -pop-state %t.a %t1.o -M | \
+// RUN:   FileCheck -check-prefix=NO-WHOLE %s
+// NO-WHOLE-NOT: _bar
+
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/shared.s -o %t3.o
+// RUN: ld.lld -shared %t3.o -soname libfoo -o %t.so
+
+// RUN: ld.lld -o %t.exe -push-state -as-needed %t.so %t1.o
+// RUN: llvm-readobj -dynamic-table %t.exe | FileCheck -check-prefix=AS-NEEDED %s
+// AS-NEEDED-NOT: NEEDED Shared library: [libfoo]
+
+// RUN: ld.lld -o %t.exe -push-state -as-needed -pop-state %t.so %t1.o
+// RUN: llvm-readobj -dynamic-table %t.exe | FileCheck -check-prefix=NO-AS-NEEDED %s
+// NO-AS-NEEDED: NEEDED Shared library: [libfoo]
+
+
+// RUN: mkdir -p %t.dir
+// RUN: cp %t.so %t.dir/libfoo.so
+// RUN: ld.lld -o %t.exe -L%t.dir -push-state -static -pop-state  %t1.o -lfoo
+// RUN: not ld.lld -o %t.exe -L%t.dir -push-state -static %t1.o -lfoo
+
+.globl _start
+_start: