From 05da2fe52162c80dfa18aedf70cf73cb11201811 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Wed, 13 Nov 2019 13:15:01 -0800
Subject: Sink all InitializePasses.h includes

This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.

I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
  recompiles    touches affected_files  header
  342380        95      3604    llvm/include/llvm/ADT/STLExtras.h
  314730        234     1345    llvm/include/llvm/InitializePasses.h
  307036        118     2602    llvm/include/llvm/ADT/APInt.h
  213049        59      3611    llvm/include/llvm/Support/MathExtras.h
  170422        47      3626    llvm/include/llvm/Support/Compiler.h
  162225        45      3605    llvm/include/llvm/ADT/Optional.h
  158319        63      2513    llvm/include/llvm/ADT/Triple.h
  140322        39      3598    llvm/include/llvm/ADT/StringRef.h
  137647        59      2333    llvm/include/llvm/Support/Error.h
  131619        73      1803    llvm/include/llvm/Support/FileSystem.h

Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.

Reviewers: bkramer, asbirlea, bollu, jdoerfert

Differential Revision: https://reviews.llvm.org/D70211
---
 llvm/lib/Transforms/Scalar/Scalarizer.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'llvm/lib/Transforms/Scalar/Scalarizer.cpp')

diff --git a/llvm/lib/Transforms/Scalar/Scalarizer.cpp b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
index 2ee1a3a95f2..821cb4ee85a 100644
--- a/llvm/lib/Transforms/Scalar/Scalarizer.cpp
+++ b/llvm/lib/Transforms/Scalar/Scalarizer.cpp
@@ -13,6 +13,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/Scalar/Scalarizer.h"
 #include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Twine.h"
@@ -33,12 +34,12 @@
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/Options.h"
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Scalar/Scalarizer.h"
 #include <cassert>
 #include <cstdint>
 #include <iterator>
-- 
cgit v1.2.3