[PATCH] D21113: Add support for case-insensitive header lookup

[Hans Wennborg via cfe-commits]

hans added a comment.

In http://reviews.llvm.org/D21113#452431, @thakis wrote:

> For performance: Can you check how build times for some large target in Chromium on Linux targeting Windows compares with this vs having the sdk in a fat mount? That would give us some data.


I measured compile times (perf stat -r5) of the same V8 file as above on Linux, but now targeting Windows:

  SDK in vfat-mounted file:                       5.84s +- 1.91%
  SDK on normal fs with -fcase-insensitive-paths: 7.18s +- 3.06%
  As above, with directory bloom filters:         6.08s +- 0.76%

This makes my patch look slower, but it's a lot more convenient than setting up that file system.

> The discussion in the include case warning thread sounds like MS might update its headers to have #include lines matching actual file case, so hopefully this won't be needed at all eventually.


That would be pretty cool!


================
Comment at: lib/Basic/VirtualFileSystem.cpp:410
@@ +409,3 @@
+  std::error_code EC;
+  directory_iterator I = Base->dir_begin(Dir, EC), E;
+
----------------
compnerd wrote:
> Thats slightly difficult to read (the `E` directory_iterator.
You're right. Moving the declaration of E to its own line further down.


http://reviews.llvm.org/D21113