llvm/lib/CodeGen/Spiller.h
Wei Mi 1145b58255 Recommit r265309 after fixed an invalid memory reference bug happened
when DenseMap growed and moved memory. I verified it fixed the bootstrap
problem on x86_64-linux-gnu but I cannot verify whether it fixes
the bootstrap error on clang-ppc64be-linux. I will watch the build-bot
result closely.

Replace analyzeSiblingValues with new algorithm to fix its compile
time issue. The patch is to solve PR17409 and its duplicates.

analyzeSiblingValues is a N x N complexity algorithm where N is
the number of siblings generated by reg splitting. Although it
causes siginificant compile time issue when N is large, it is also
important for performance since it removes redundent spills and
enables rematerialization.

To solve the compile time issue, the patch removes analyzeSiblingValues
and replaces it with lower cost alternatives containing two parts. The
first part creates a new spill hoisting method in postOptimization of
register allocation. It does spill hoisting at once after all the spills
are generated instead of inside every instance of selectOrSplit. The
second part queries the define expr of the original register for
rematerializaiton and keep it always available during register allocation
even if it is already dead. It deletes those dead instructions only in
postOptimization. With the two parts in the patch, it can remove
analyzeSiblingValues without sacrificing performance.

Differential Revision: http://reviews.llvm.org/D15302


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@265547 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-06 15:41:07 +00:00

43 lines
1.2 KiB
C++

//===-- llvm/CodeGen/Spiller.h - Spiller -*- C++ -*------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_SPILLER_H
#define LLVM_LIB_CODEGEN_SPILLER_H
namespace llvm {
class LiveRangeEdit;
class MachineFunction;
class MachineFunctionPass;
class VirtRegMap;
class LiveIntervals;
/// Spiller interface.
///
/// Implementations are utility classes which insert spill or remat code on
/// demand.
class Spiller {
virtual void anchor();
public:
virtual ~Spiller() = 0;
/// spill - Spill the LRE.getParent() live interval.
virtual void spill(LiveRangeEdit &LRE) = 0;
virtual void postOptimization(){};
};
/// Create and return a spiller that will insert spill code directly instead
/// of deferring though VirtRegMap.
Spiller *createInlineSpiller(MachineFunctionPass &pass,
MachineFunction &mf,
VirtRegMap &vrm);
}
#endif