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086791eca2
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
68 lines
2.2 KiB
C++
68 lines
2.2 KiB
C++
//===-- SystemZSubtarget.cpp - SystemZ subtarget information --------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "SystemZSubtarget.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/Support/Host.h"
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#include "MCTargetDesc/SystemZMCTargetDesc.h"
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#define GET_SUBTARGETINFO_TARGET_DESC
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#define GET_SUBTARGETINFO_CTOR
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#include "SystemZGenSubtargetInfo.inc"
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using namespace llvm;
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// Pin the vtabel to this file.
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void SystemZSubtarget::anchor() {}
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SystemZSubtarget::SystemZSubtarget(const std::string &TT,
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const std::string &CPU,
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const std::string &FS)
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: SystemZGenSubtargetInfo(TT, CPU, FS), HasDistinctOps(false),
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HasLoadStoreOnCond(false), HasHighWord(false), HasFPExtension(false),
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HasFastSerialization(false), TargetTriple(TT) {
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std::string CPUName = CPU;
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if (CPUName.empty())
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CPUName = "generic";
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#if defined(__linux__) && defined(__s390x__)
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if (CPUName == "generic")
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CPUName = sys::getHostCPUName();
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#endif
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// Parse features string.
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ParseSubtargetFeatures(CPUName, FS);
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}
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// Return true if GV binds locally under reloc model RM.
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static bool bindsLocally(const GlobalValue *GV, Reloc::Model RM) {
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// For non-PIC, all symbols bind locally.
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if (RM == Reloc::Static)
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return true;
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return GV->hasLocalLinkage() || !GV->hasDefaultVisibility();
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}
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bool SystemZSubtarget::isPC32DBLSymbol(const GlobalValue *GV,
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Reloc::Model RM,
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CodeModel::Model CM) const {
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// PC32DBL accesses require the low bit to be clear. Note that a zero
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// value selects the default alignment and is therefore OK.
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if (GV->getAlignment() == 1)
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return false;
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// For the small model, all locally-binding symbols are in range.
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if (CM == CodeModel::Small)
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return bindsLocally(GV, RM);
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// For Medium and above, assume that the symbol is not within the 4GB range.
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// Taking the address of locally-defined text would be OK, but that
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// case isn't easy to detect.
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return false;
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}
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