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);
42 StrictAlign("arm-strict-align", cl::Hidden,
43 cl::desc("Disallow all unaligned memory accesses"));
45 ARMSubtarget::ARMSubtarget(const std::string &TT, const std::string &CPU,
46 const std::string &FS, const TargetOptions &Options)
47 : ARMGenSubtargetInfo(TT, CPU, FS)
48 , ARMProcFamily(Others)
53 , TargetABI(ARM_ABI_APCS) {
54 initializeEnvironment();
55 resetSubtargetFeatures(CPU, FS);
58 void ARMSubtarget::initializeEnvironment() {
69 UseNEONForSinglePrecisionFP = false;
70 UseMulOps = UseFusedMulOps;
72 HasVMLxForwarding = false;
78 PostRAScheduler = false;
79 IsR9Reserved = ReserveR9;
81 SupportsTailCall = false;
84 HasHardwareDivide = false;
85 HasHardwareDivideInARM = false;
86 HasT2ExtractPack = false;
87 HasDataBarrier = false;
88 Pref32BitThumb = false;
89 AvoidCPSRPartialUpdate = false;
90 AvoidMOVsShifterOperand = false;
92 HasMPExtension = false;
95 AllowsUnalignedMem = false;
101 void ARMSubtarget::resetSubtargetFeatures(const MachineFunction *MF) {
102 AttributeSet FnAttrs = MF->getFunction()->getAttributes();
103 Attribute CPUAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
105 Attribute FSAttr = FnAttrs.getAttribute(AttributeSet::FunctionIndex,
108 !CPUAttr.hasAttribute(Attribute::None) ?CPUAttr.getValueAsString() : "";
110 !FSAttr.hasAttribute(Attribute::None) ? FSAttr.getValueAsString() : "";
112 initializeEnvironment();
113 resetSubtargetFeatures(CPU, FS);
117 void ARMSubtarget::resetSubtargetFeatures(StringRef CPU, StringRef FS) {
118 if (CPUString.empty())
119 CPUString = "generic";
121 // Insert the architecture feature derived from the target triple into the
122 // feature string. This is important for setting features that are implied
123 // based on the architecture version.
124 std::string ArchFS = ARM_MC::ParseARMTriple(TargetTriple.getTriple(),
128 ArchFS = ArchFS + "," + FS.str();
132 ParseSubtargetFeatures(CPUString, ArchFS);
134 // Thumb2 implies at least V6T2. FIXME: Fix tests to explicitly specify a
135 // ARM version or CPU and then remove this.
136 if (!HasV6T2Ops && hasThumb2())
137 HasV4TOps = HasV5TOps = HasV5TEOps = HasV6Ops = HasV6T2Ops = true;
139 // Keep a pointer to static instruction cost data for the specified CPU.
140 SchedModel = getSchedModelForCPU(CPUString);
142 // Initialize scheduling itinerary for the specified CPU.
143 InstrItins = getInstrItineraryForCPU(CPUString);
145 if ((TargetTriple.getTriple().find("eabi") != std::string::npos) ||
146 (isTargetIOS() && isMClass()))
147 // FIXME: We might want to separate AAPCS and EABI. Some systems, e.g.
148 // Darwin-EABI conforms to AACPS but not the rest of EABI.
149 TargetABI = ARM_ABI_AAPCS;
155 UseMovt = hasV6T2Ops();
157 IsR9Reserved = ReserveR9 | !HasV6Ops;
158 UseMovt = DarwinUseMOVT && hasV6T2Ops();
159 SupportsTailCall = !getTargetTriple().isOSVersionLT(5, 0);
162 if (!isThumb() || hasThumb2())
163 PostRAScheduler = true;
166 // Assume pre-ARMv6 doesn't support unaligned accesses.
168 // ARMv6 may or may not support unaligned accesses depending on the
169 // SCTLR.U bit, which is architecture-specific. We assume ARMv6
170 // Darwin targets support unaligned accesses, and others don't.
172 // ARMv7 always has SCTLR.U set to 1, but it has a new SCTLR.A bit
173 // which raises an alignment fault on unaligned accesses. Linux
174 // defaults this bit to 0 and handles it as a system-wide (not
175 // per-process) setting. It is therefore safe to assume that ARMv7+
176 // targets support unaligned accesses.
178 // The above behavior is consistent with GCC.
179 if (hasV7Ops() || (hasV6Ops() && isTargetDarwin()))
180 AllowsUnalignedMem = true;
183 // NEON f32 ops are non-IEEE 754 compliant. Darwin is ok with it by default.
184 uint64_t Bits = getFeatureBits();
185 if ((Bits & ARM::ProcA5 || Bits & ARM::ProcA8) && // Where this matters
186 (Options.UnsafeFPMath || isTargetDarwin()))
187 UseNEONForSinglePrecisionFP = true;
190 /// GVIsIndirectSymbol - true if the GV will be accessed via an indirect symbol.
192 ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
193 Reloc::Model RelocM) const {
194 if (RelocM == Reloc::Static)
197 // Materializable GVs (in JIT lazy compilation mode) do not require an extra
199 bool isDecl = GV->hasAvailableExternallyLinkage();
200 if (GV->isDeclaration() && !GV->isMaterializable())
203 if (!isTargetDarwin()) {
204 // Extra load is needed for all externally visible.
205 if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
209 if (RelocM == Reloc::PIC_) {
210 // If this is a strong reference to a definition, it is definitely not
212 if (!isDecl && !GV->isWeakForLinker())
215 // Unless we have a symbol with hidden visibility, we have to go through a
216 // normal $non_lazy_ptr stub because this symbol might be resolved late.
217 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
220 // If symbol visibility is hidden, we have a stub for common symbol
221 // references and external declarations.
222 if (isDecl || GV->hasCommonLinkage())
223 // Hidden $non_lazy_ptr reference.
228 // If this is a strong reference to a definition, it is definitely not
230 if (!isDecl && !GV->isWeakForLinker())
233 // Unless we have a symbol with hidden visibility, we have to go through a
234 // normal $non_lazy_ptr stub because this symbol might be resolved late.
235 if (!GV->hasHiddenVisibility()) // Non-hidden $non_lazy_ptr reference.
243 unsigned ARMSubtarget::getMispredictionPenalty() const {
244 return SchedModel->MispredictPenalty;
247 bool ARMSubtarget::enablePostRAScheduler(
248 CodeGenOpt::Level OptLevel,
249 TargetSubtargetInfo::AntiDepBreakMode& Mode,
250 RegClassVector& CriticalPathRCs) const {
251 Mode = TargetSubtargetInfo::ANTIDEP_CRITICAL;
252 CriticalPathRCs.clear();
253 CriticalPathRCs.push_back(&ARM::GPRRegClass);
254 return PostRAScheduler && OptLevel >= CodeGenOpt::Default;