1 //===-- ARMSubtarget.cpp - ARM Subtarget Information ----------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ARM specific subclass of TargetSubtargetInfo.
12 //===----------------------------------------------------------------------===//
14 #include "ARMSubtarget.h"
15 #include "ARMBaseInstrInfo.h"
16 #include "ARMBaseRegisterInfo.h"
17 #include "llvm/IR/Attributes.h"
18 #include "llvm/IR/GlobalValue.h"
19 #include "llvm/IR/Function.h"
20 #include "llvm/Support/CommandLine.h"
21 #include "llvm/Target/TargetInstrInfo.h"
22 #include "llvm/Target/TargetOptions.h"
24 #define GET_SUBTARGETINFO_TARGET_DESC
25 #define GET_SUBTARGETINFO_CTOR
26 #include "ARMGenSubtargetInfo.inc"
31 ReserveR9("arm-reserve-r9", cl::Hidden,
32 cl::desc("Reserve R9, making it unavailable as GPR"));
35 DarwinUseMOVT("arm-darwin-use-movt", cl::init(true), cl::Hidden);
38 UseFusedMulOps("arm-use-mulops",
39 cl::init(true), cl::Hidden);
47 static cl::opt<AlignMode>
48 Align(cl::desc("Load/store alignment support"),
49 cl::Hidden, cl::init(DefaultAlign),
51 clEnumValN(DefaultAlign, "arm-default-align",
52 "Generate unaligned accesses only on hardware/OS "
53 "combinations that are known to support them"),
54 clEnumValN(StrictAlign, "arm-strict-align",
55 "Disallow all unaligned memory accesses"),
56 clEnumValN(NoStrictAlign, "arm-no-strict-align",
57 "Allow unaligned memory accesses"),
60 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
61 const std::string &FS, const TargetOptions &Options)
62 : ARMGenSubtargetInfo(TT, CPU, FS)
63 , ARMProcFamily(Others)
68 , TargetABI(ARM_ABI_APCS) {
69 initializeEnvironment();
70 resetSubtargetFeatures(CPU, FS);
73 void ARMSubtarget::initializeEnvironment() {
85 UseNEONForSinglePrecisionFP = false;
86 UseMulOps = UseFusedMulOps;
88 HasVMLxForwarding = false;
94 PostRAScheduler = false;
95 IsR9Reserved = ReserveR9;
97 SupportsTailCall = false;
100 HasHardwareDivide = false;
101 HasHardwareDivideInARM = false;
102 HasT2ExtractPack = false;
103 HasDataBarrier = false;
104 Pref32BitThumb = false;
105 AvoidCPSRPartialUpdate = false;
106 AvoidMOVsShifterOperand = false;
108 HasMPExtension = false;
111 HasTrustZone = false;
112 AllowsUnalignedMem = false;
115 UnsafeFPMath = false;
118 void ARMSubtarget::resetSubtargetFeatures(const MachineFunction *MF) {
119 AttributeSet FnAttrs = MF->getFunction()->getAttributes();
120 Attribute CPUAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
122 Attribute FSAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
125 !CPUAttr.hasAttribute(Attribute::None) ?CPUAttr.getValueAsString() : "";
127 !FSAttr.hasAttribute(Attribute::None) ? FSAttr.getValueAsString() : "";
129 initializeEnvironment();
130 resetSubtargetFeatures(CPU, FS);
134 void ARMSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
135 if (CPUString.empty())
136 CPUString = "generic";
138 // Insert the architecture feature derived from the target triple into the
139 // feature string. This is important for setting features that are implied
140 // based on the architecture version.
141 std::string ArchFS = ARM_MC::ParseARMTriple(TargetTriple.getTriple(),
145 ArchFS = ArchFS + "," + FS.str();
149 ParseSubtargetFeatures(CPUString, ArchFS);
151 // Thumb2 implies at least V6T2. FIXME: Fix tests to explicitly specify a
152 // ARM version or CPU and then remove this.
153 if (!HasV6T2Ops && hasThumb2())
154 HasV4TOps = HasV5TOps = HasV5TEOps = HasV6Ops = HasV6T2Ops = true;
156 // Keep a pointer to static instruction cost data for the specified CPU.
157 SchedModel = getSchedModelForCPU(CPUString);
159 // Initialize scheduling itinerary for the specified CPU.
160 InstrItins = getInstrItineraryForCPU(CPUString);
162 if ((TargetTriple.getTriple().find("eabi") != std::string::npos) ||
163 (isTargetIOS() && isMClass()))
164 // FIXME: We might want to separate AAPCS and EABI. Some systems, e.g.
165 // Darwin-EABI conforms to AACPS but not the rest of EABI.
166 TargetABI = ARM_ABI_AAPCS;
172 UseMovt = hasV6T2Ops();
174 IsR9Reserved = ReserveR9 | !HasV6Ops;
175 UseMovt = DarwinUseMOVT && hasV6T2Ops();
176 SupportsTailCall = !getTargetTriple().isOSVersionLT(5, 0);
179 if (!isThumb() || hasThumb2())
180 PostRAScheduler = true;
184 // Assume pre-ARMv6 doesn't support unaligned accesses.
186 // ARMv6 may or may not support unaligned accesses depending on the
187 // SCTLR.U bit, which is architecture-specific. We assume ARMv6
188 // Darwin targets support unaligned accesses, and others don't.
190 // ARMv7 always has SCTLR.U set to 1, but it has a new SCTLR.A bit
191 // which raises an alignment fault on unaligned accesses. Linux
192 // defaults this bit to 0 and handles it as a system-wide (not
193 // per-process) setting. It is therefore safe to assume that ARMv7+
194 // Linux targets support unaligned accesses. The same goes for NaCl.
196 // The above behavior is consistent with GCC.
197 AllowsUnalignedMem = (
198 (hasV7Ops() && (isTargetLinux() || isTargetNaCl())) ||
199 (hasV6Ops() && isTargetDarwin()));
202 AllowsUnalignedMem = false;
205 AllowsUnalignedMem = true;
209 // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
210 uint64_t Bits = getFeatureBits();
211 if ((Bits & ARM::ProcA5 || Bits & ARM::ProcA8) && // Where this matters
212 (Options.UnsafeFPMath || isTargetDarwin()))
213 UseNEONForSinglePrecisionFP = true;
216 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
218 ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
219 Reloc::Model RelocM) const {
220 if (RelocM == Reloc::Static)
223 // Materializable GVs (in JIT lazy compilation mode) do not require an extra
225 bool isDecl = GV->hasAvailableExternallyLinkage();
226 if (GV->isDeclaration() && !GV->isMaterializable())
229 if (!isTargetDarwin()) {
230 // Extra load is needed for all externally visible.
231 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
235 if (RelocM == Reloc::PIC_) {
236 // If this is a strong reference to a definition, it is definitely not
238 if (!isDecl && !GV->isWeakForLinker())
241 // Unless we have a symbol with hidden visibility, we have to go through a
242 // normal $non_lazy_ptr stub because this symbol might be resolved late.
243 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
246 // If symbol visibility is hidden, we have a stub for common symbol
247 // references and external declarations.
248 if (isDecl || GV->hasCommonLinkage())
249 // Hidden $non_lazy_ptr reference.
254 // If this is a strong reference to a definition, it is definitely not
256 if (!isDecl && !GV->isWeakForLinker())
259 // Unless we have a symbol with hidden visibility, we have to go through a
260 // normal $non_lazy_ptr stub because this symbol might be resolved late.
261 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
269 unsigned ARMSubtarget::getMispredictionPenalty() const {
270 return SchedModel->MispredictPenalty;
273 bool ARMSubtarget::enablePostRAScheduler(
274 CodeGenOpt::Level OptLevel,
275 TargetSubtargetInfo::AntiDepBreakMode& Mode,
276 RegClassVector& CriticalPathRCs) const {
277 Mode = TargetSubtargetInfo::ANTIDEP_CRITICAL;
278 CriticalPathRCs.clear();
279 CriticalPathRCs.push_back(&ARM::GPRRegClass);
280 return PostRAScheduler && OptLevel >= CodeGenOpt::Default;