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
diff --git a/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp b/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp
index 0a38386..a2c8c75 100644
--- a/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp
+++ b/llvm/lib/CodeGen/PostRAHazardRecognizer.cpp
@@ -1,16 +1,3 @@
-//===----- PostRAHazardRecognizer.cpp - hazard recognizer -----------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-/// \file
-/// This runs the hazard recognizer and emits noops when necessary. This
-/// gives targets a way to run the hazard recognizer without running one of
-/// the schedulers. Example use cases for this pass would be:
-///
/// - Targets that need the hazard recognizer to be run at -O0.
/// - Targets that want to guarantee that hazards at the beginning of
/// scheduling regions are handled correctly. The post-RA scheduler is
@@ -32,6 +19,7 @@
#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"