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llvm-mirror/include/llvm/Analysis/IntervalPartition.h
Reid Kleckner 68092989f3 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
2019-11-13 16:34:37 -08:00

109 lines
4.0 KiB
C++

//===- IntervalPartition.h - Interval partition Calculation -----*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains the declaration of the IntervalPartition class, which
// calculates and represents the interval partition of a function, or a
// preexisting interval partition.
//
// In this way, the interval partition may be used to reduce a flow graph down
// to its degenerate single node interval partition (unless it is irreducible).
//
// TODO: The IntervalPartition class should take a bool parameter that tells
// whether it should add the "tails" of an interval to an interval itself or if
// they should be represented as distinct intervals.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_INTERVALPARTITION_H
#define LLVM_ANALYSIS_INTERVALPARTITION_H
#include "llvm/Pass.h"
#include <map>
#include <vector>
namespace llvm {
class BasicBlock;
class Interval;
//===----------------------------------------------------------------------===//
//
// IntervalPartition - This class builds and holds an "interval partition" for
// a function. This partition divides the control flow graph into a set of
// maximal intervals, as defined with the properties above. Intuitively, an
// interval is a (possibly nonexistent) loop with a "tail" of non-looping
// nodes following it.
//
class IntervalPartition : public FunctionPass {
using IntervalMapTy = std::map<BasicBlock *, Interval *>;
IntervalMapTy IntervalMap;
using IntervalListTy = std::vector<Interval *>;
Interval *RootInterval = nullptr;
std::vector<Interval *> Intervals;
public:
static char ID; // Pass identification, replacement for typeid
IntervalPartition();
// run - Calculate the interval partition for this function
bool runOnFunction(Function &F) override;
// IntervalPartition ctor - Build a reduced interval partition from an
// existing interval graph. This takes an additional boolean parameter to
// distinguish it from a copy constructor. Always pass in false for now.
IntervalPartition(IntervalPartition &I, bool);
// print - Show contents in human readable format...
void print(raw_ostream &O, const Module* = nullptr) const override;
// getRootInterval() - Return the root interval that contains the starting
// block of the function.
inline Interval *getRootInterval() { return RootInterval; }
// isDegeneratePartition() - Returns true if the interval partition contains
// a single interval, and thus cannot be simplified anymore.
bool isDegeneratePartition() { return Intervals.size() == 1; }
// TODO: isIrreducible - look for triangle graph.
// getBlockInterval - Return the interval that a basic block exists in.
inline Interval *getBlockInterval(BasicBlock *BB) {
IntervalMapTy::iterator I = IntervalMap.find(BB);
return I != IntervalMap.end() ? I->second : nullptr;
}
// getAnalysisUsage - Implement the Pass API
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
}
// Interface to Intervals vector...
const std::vector<Interval*> &getIntervals() const { return Intervals; }
// releaseMemory - Reset state back to before function was analyzed
void releaseMemory() override;
private:
// addIntervalToPartition - Add an interval to the internal list of intervals,
// and then add mappings from all of the basic blocks in the interval to the
// interval itself (in the IntervalMap).
void addIntervalToPartition(Interval *I);
// updatePredecessors - Interval generation only sets the successor fields of
// the interval data structures. After interval generation is complete,
// run through all of the intervals and propagate successor info as
// predecessor info.
void updatePredecessors(Interval *Int);
};
} // end namespace llvm
#endif // LLVM_ANALYSIS_INTERVALPARTITION_H