[LLD] Remove global state in lldCommon

Move all variables at file-scope or function-static-scope into a hosting structure (lld::CommonLinkerContext) that lives at lldMain()-scope. Drivers will inherit from this structure and add their own global state, in the same way as for the existing COFFLinkerContext.

See discussion in https://lists.llvm.org/pipermail/llvm-dev/2021-June/151184.html

Differential Revision: https://reviews.llvm.org/D108850

1 files changed, 33 insertions, 16 deletions

diff --git a/lld/tools/lld/lld.cpp b/lld/tools/lld/lld.cpp
index cad97f2153c2..7cf55e91d30e 100644
--- a/lld/tools/lld/lld.cpp
+++ b/lld/tools/lld/lld.cpp
@@ -87,6 +87,8 @@ static bool isPETarget(std::vector<const char *> &v) {
   // Expand response files (arguments in the form of @<filename>)
   // to allow detecting the -m argument from arguments in them.
   SmallVector<const char *, 256> expandedArgs(v.data(), v.data() + v.size());
+  BumpPtrAllocator a;
+  StringSaver saver(a);
   cl::ExpandResponseFiles(saver, getDefaultQuotingStyle(), expandedArgs);
   for (auto it = expandedArgs.begin(); it + 1 != expandedArgs.end(); ++it) {
     if (StringRef(*it) != "-m")
@@ -134,27 +136,43 @@ static Flavor parseFlavor(std::vector<const char *> &v) {
   return parseProgname(arg0);
 }
 
+static bool inTestOutputDisabled = false;
+
 /// Universal linker main(). This linker emulates the gnu, darwin, or
 /// windows linker based on the argv[0] or -flavor option.
 static int lldMain(int argc, const char **argv, llvm::raw_ostream &stdoutOS,
                    llvm::raw_ostream &stderrOS, bool exitEarly = true) {
   std::vector<const char *> args(argv, argv + argc);
-  switch (parseFlavor(args)) {
-  case Gnu:
-    if (isPETarget(args))
-      return !mingw::link(args, exitEarly, stdoutOS, stderrOS);
-    return !elf::link(args, exitEarly, stdoutOS, stderrOS);
-  case WinLink:
-    return !coff::link(args, exitEarly, stdoutOS, stderrOS);
-  case Darwin:
-    return !macho::link(args, exitEarly, stdoutOS, stderrOS);
-  case Wasm:
-    return !lld::wasm::link(args, exitEarly, stdoutOS, stderrOS);
-  default:
+  auto link = [&args]() {
+    Flavor f = parseFlavor(args);
+    if (f == Gnu && isPETarget(args))
+      return mingw::link;
+    if (f == Gnu)
+      return elf::link;
+    if (f == WinLink)
+      return coff::link;
+    if (f == Darwin)
+      return macho::link;
+    if (f == Wasm)
+      return lld::wasm::link;
     die("lld is a generic driver.\n"
         "Invoke ld.lld (Unix), ld64.lld (macOS), lld-link (Windows), wasm-ld"
         " (WebAssembly) instead");
-  }
+  }();
+  // Run the driver. If an error occurs, false will be returned.
+  int r = !link(args, stdoutOS, stderrOS, exitEarly, inTestOutputDisabled);
+
+  // Exit immediately if we don't need to return to the caller.
+  // This saves time because the overhead of calling destructors
+  // for all globally-allocated objects is not negligible.
+  if (exitEarly)
+    exitLld(r);
+
+  // Delete the global context and clear the global context pointer, so that it
+  // cannot be accessed anymore.
+  CommonLinkerContext::destroy();
+
+  return r;
 }
 
 // Similar to lldMain except that exceptions are caught.
@@ -176,7 +194,7 @@ SafeReturn lld::safeLldMain(int argc, const char **argv,
   // Cleanup memory and reset everything back in pristine condition. This path
   // is only taken when LLD is in test, or when it is used as a library.
   llvm::CrashRecoveryContext crc;
-  if (!crc.RunSafely([&]() { errorHandler().reset(); })) {
+  if (!crc.RunSafely([&]() { CommonLinkerContext::destroy(); })) {
     // The memory is corrupted beyond any possible recovery.
     return {r, /*canRunAgain=*/false};
   }
@@ -207,8 +225,7 @@ int main(int argc, const char **argv) {
 
   for (unsigned i = inTestVerbosity(); i > 0; --i) {
     // Disable stdout/stderr for all iterations but the last one.
-    if (i != 1)
-      errorHandler().disableOutput = true;
+    inTestOutputDisabled = (i != 1);
 
     // Execute one iteration.
     auto r = safeLldMain(argc, argv, llvm::outs(), llvm::errs());