[PATCH] D86406: Speedup llvm-dwarfdump 3.9x

[Jan Kratochvil via Phabricator via llvm-commits]

jankratochvil updated this revision to Diff 287695.
jankratochvil added a comment.

In D86406#2235959 <https://reviews.llvm.org/D86406#2235959>, @joerg wrote:

> Can you change `raw_fd_ostream::has_colors` to memoize the result of `FileDescriptorHasColors(FD)` instead?

Done, yes, that looks simple and it works. The new code is not thread-safe but other member variables there also are not.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D86406/new/

https://reviews.llvm.org/D86406

Files:
  llvm/include/llvm/Support/raw_ostream.h
  llvm/lib/Support/raw_ostream.cpp


Index: llvm/lib/Support/raw_ostream.cpp
===================================================================
--- llvm/lib/Support/raw_ostream.cpp
+++ llvm/lib/Support/raw_ostream.cpp
@@ -857,8 +857,10 @@
   return sys::Process::FileDescriptorIsDisplayed(FD);
 }
 
-bool raw_fd_ostream::has_colors() const {
-  return sys::Process::FileDescriptorHasColors(FD);
+bool raw_fd_ostream::has_colors() {
+  if (!HasColors)
+    HasColors = sys::Process::FileDescriptorHasColors(FD);
+  return *HasColors;
 }
 
 Expected<sys::fs::FileLocker> raw_fd_ostream::lock() {
Index: llvm/include/llvm/Support/raw_ostream.h
===================================================================
--- llvm/include/llvm/Support/raw_ostream.h
+++ llvm/include/llvm/Support/raw_ostream.h
@@ -295,7 +295,7 @@
 
   /// This function determines if this stream is displayed and supports colors.
   /// The result is unaffected by calls to enable_color().
-  virtual bool has_colors() const { return is_displayed(); }
+  virtual bool has_colors() { return is_displayed(); }
 
   // Enable or disable colors. Once enable_colors(false) is called,
   // changeColor() has no effect until enable_colors(true) is called.
@@ -412,6 +412,7 @@
   int FD;
   bool ShouldClose;
   bool SupportsSeeking = false;
+  Optional<bool> HasColors;
 
 #ifdef _WIN32
   /// True if this fd refers to a Windows console device. Mintty and other
@@ -479,7 +480,7 @@
 
   bool is_displayed() const override;
 
-  bool has_colors() const override;
+  bool has_colors() override;
 
   std::error_code error() const { return EC; }
 


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