1//===-- SystemZSubtarget.cpp - SystemZ subtarget information --------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "SystemZSubtarget.h"
10#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
11#include "llvm/IR/GlobalVariable.h"
12#include "llvm/Target/TargetMachine.h"
13
14using namespace llvm;
15
16#define DEBUG_TYPE "systemz-subtarget"
17
18#define GET_SUBTARGETINFO_TARGET_DESC
19#define GET_SUBTARGETINFO_CTOR
20#include "SystemZGenSubtargetInfo.inc"
21
22static cl::opt<bool> UseSubRegLiveness(
23 "systemz-subreg-liveness",
24 cl::desc("Enable subregister liveness tracking for SystemZ (experimental)"),
25 cl::Hidden);
26
27// Pin the vtable to this file.
28void SystemZSubtarget::anchor() {}
29
30SystemZSubtarget &SystemZSubtarget::initializeSubtargetDependencies(
31 StringRef CPU, StringRef TuneCPU, StringRef FS) {
32 if (CPU.empty())
33 CPU = "generic";
34 if (TuneCPU.empty())
35 TuneCPU = CPU;
36 // Parse features string.
37 ParseSubtargetFeatures(CPU, TuneCPU, FS);
38
39 // -msoft-float implies -mno-vx.
40 if (HasSoftFloat)
41 HasVector = false;
42
43 // -mno-vx implicitly disables all vector-related features.
44 if (!HasVector) {
45 HasVectorEnhancements1 = false;
46 HasVectorEnhancements2 = false;
47 HasVectorEnhancements3 = false;
48 HasVectorPackedDecimal = false;
49 HasVectorPackedDecimalEnhancement = false;
50 HasVectorPackedDecimalEnhancement2 = false;
51 HasVectorPackedDecimalEnhancement3 = false;
52 }
53
54 return *this;
55}
56
57SystemZCallingConventionRegisters *
58SystemZSubtarget::initializeSpecialRegisters() {
59 if (isTargetXPLINK64())
60 return new SystemZXPLINK64Registers;
61 else if (isTargetELF())
62 return new SystemZELFRegisters;
63 llvm_unreachable("Invalid Calling Convention. Cannot initialize Special "
64 "Call Registers!");
65}
66
67SystemZSubtarget::SystemZSubtarget(const Triple &TT, const std::string &CPU,
68 const std::string &TuneCPU,
69 const std::string &FS,
70 const TargetMachine &TM)
71 : SystemZGenSubtargetInfo(TT, CPU, TuneCPU, FS), TargetTriple(TT),
72 SpecialRegisters(initializeSpecialRegisters()),
73 InstrInfo(initializeSubtargetDependencies(CPU, TuneCPU, FS)),
74 TLInfo(TM, *this), FrameLowering(SystemZFrameLowering::create(STI: *this)) {}
75
76bool SystemZSubtarget::enableSubRegLiveness() const {
77 return UseSubRegLiveness;
78}
79
80bool SystemZSubtarget::isAddressedViaADA(const GlobalValue *GV) const {
81 if (const auto *GO = dyn_cast<GlobalObject>(Val: GV)) {
82 // A R/O variable is placed in code section. If the R/O variable has as
83 // least two byte alignment, then generated code can use relative
84 // instructions to address the variable. Otherwise, use the ADA to address
85 // the variable.
86 if (auto *GV = dyn_cast<GlobalVariable>(Val: GO))
87 if (GV->getAlign() && (*GV->getAlign()).value() & 0x1)
88 return true;
89
90 // getKindForGlobal only works with definitions
91 if (GO->isDeclaration()) {
92 return true;
93 }
94
95 // check AvailableExternallyLinkage here as getKindForGlobal() asserts
96 if (GO->hasAvailableExternallyLinkage()) {
97 return true;
98 }
99
100 SectionKind GOKind = TargetLoweringObjectFile::getKindForGlobal(
101 GO, TM: TLInfo.getTargetMachine());
102 if (!GOKind.isReadOnly()) {
103 return true;
104 }
105
106 return false; // R/O variable with multiple of 2 byte alignment
107 }
108 return true;
109}
110
111bool SystemZSubtarget::isPC32DBLSymbol(const GlobalValue *GV,
112 CodeModel::Model CM) const {
113 if (isTargetzOS())
114 return !isAddressedViaADA(GV);
115
116 // PC32DBL accesses require the low bit to be clear.
117 //
118 // FIXME: Explicitly check for functions: the datalayout is currently
119 // missing information about function pointers.
120 const DataLayout &DL = GV->getDataLayout();
121 if (GV->getPointerAlignment(DL) == 1 && !GV->getValueType()->isFunctionTy())
122 return false;
123
124 // For the small model, all locally-binding symbols are in range.
125 if (CM == CodeModel::Small)
126 return TLInfo.getTargetMachine().shouldAssumeDSOLocal(GV);
127
128 // For Medium and above, assume that the symbol is not within the 4GB range.
129 // Taking the address of locally-defined text would be OK, but that
130 // case isn't easy to detect.
131 return false;
132}
133