[PATCH] D69825: [Clang][Driver] Bypass cc1 process and re-enter driver main

[Michael Kruse via Phabricator via cfe-commits]

Meinersbur added a comment.

This patch reduced the build time from 12 to 7 minutes? Sounds too good to be true. Thanks for the work! I would primarily interested in this to avoid determining the `-cc1` command line when debugging.

However, the implementation of calling it's own main function gives the impression to be more like a hack. How much restructuring would be needed to properly create a CompilerInstance inside the driver instead?



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Comment at: clang/lib/Driver/Job.cpp:340-355
+  typedef int (*ClangDriverMainFunc)(SmallVectorImpl<const char *> &);
+  ClangDriverMainFunc ClangDriverMain = nullptr;
+
+  if (ReenterTool) {
+    StringRef F = llvm::sys::path::filename(Executable);
+    if (F.endswith_lower(".exe"))
+      F = F.drop_back(4);
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This looks fragile as it will break when the user chooses to rename the executable (`clang-cuda`, `--driver-mode=...`,...). Why not moving the ClangDriverMain logic into the clangDriver module. Or, at least, pass it through a lambda. It would also make it easier to use clangDriver as a library (if that was ever an intended use-case?!?)


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Comment at: clang/tools/driver/driver.cpp:337
+
+int ClangDriverMain(SmallVectorImpl<const char *> &argv) {
+  static LLVM_THREAD_LOCAL bool EnterPE = true;
----------------
Could you add a comment for the purpose of this function? It's not obvious outside the context of this patch.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D69825/new/

https://reviews.llvm.org/D69825