llvm/lib/Target/SystemZ/SystemZSubtarget.h
Richard Sandiford 086791eca2 Add TargetLowering::prepareVolatileOrAtomicLoad
One unusual feature of the z architecture is that the result of a
previous load can be reused indefinitely for subsequent loads, even if
a cache-coherent store to that location is performed by another CPU.
A special serializing instruction must be used if you want to force
a load to be reattempted.

Since volatile loads are not supposed to be omitted in this way,
we should insert a serializing instruction before each such load.
The same goes for atomic loads.

The patch implements this at the IR->DAG boundary, in a similar way
to atomic fences.  It is a no-op for targets other than SystemZ.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196905 91177308-0d34-0410-b5e6-96231b3b80d8
2013-12-10 10:36:34 +00:00

75 lines
2.3 KiB
C++

//===-- SystemZSubtarget.h - SystemZ subtarget information -----*- C++ -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the SystemZ specific subclass of TargetSubtargetInfo.
//
//===----------------------------------------------------------------------===//
#ifndef SYSTEMZSUBTARGET_H
#define SYSTEMZSUBTARGET_H
#include "llvm/ADT/Triple.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <string>
#define GET_SUBTARGETINFO_HEADER
#include "SystemZGenSubtargetInfo.inc"
namespace llvm {
class GlobalValue;
class StringRef;
class SystemZSubtarget : public SystemZGenSubtargetInfo {
virtual void anchor();
protected:
bool HasDistinctOps;
bool HasLoadStoreOnCond;
bool HasHighWord;
bool HasFPExtension;
bool HasFastSerialization;
private:
Triple TargetTriple;
public:
SystemZSubtarget(const std::string &TT, const std::string &CPU,
const std::string &FS);
// This is important for reducing register pressure in vector code.
virtual bool useAA() const LLVM_OVERRIDE { return true; }
// Automatically generated by tblgen.
void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
// Return true if the target has the distinct-operands facility.
bool hasDistinctOps() const { return HasDistinctOps; }
// Return true if the target has the load/store-on-condition facility.
bool hasLoadStoreOnCond() const { return HasLoadStoreOnCond; }
// Return true if the target has the high-word facility.
bool hasHighWord() const { return HasHighWord; }
// Return true if the target has the floating-point extension facility.
bool hasFPExtension() const { return HasFPExtension; }
// Return true if the target has the fast-serialization facility.
bool hasFastSerialization() const { return HasFastSerialization; }
// Return true if GV can be accessed using LARL for reloc model RM
// and code model CM.
bool isPC32DBLSymbol(const GlobalValue *GV, Reloc::Model RM,
CodeModel::Model CM) const;
bool isTargetELF() const { return TargetTriple.isOSBinFormatELF(); }
};
} // end namespace llvm
#endif