[AArch64] Make the use of FP instructions optional, but enabled by default.

This adds a new subtarget feature called FPARMv8 (implied by NEON), and
predicates the support of the FP instructions and registers on this feature.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193739 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 90 insertions, 28 deletions

diff --git a/lib/Target/AArch64/AArch64.td b/lib/Target/AArch64/AArch64.td
index e17052b4a5..083064b711 100644
--- a/lib/Target/AArch64/AArch64.td
+++ b/lib/Target/AArch64/AArch64.td
@@ -21,8 +21,11 @@ include "llvm/Target/Target.td"
 // AArch64 Subtarget features.
 //
 
+def FeatureFPARMv8 : SubtargetFeature<"fp-armv8", "HasFPARMv8", "true",
+  "Enable ARMv8 FP">;
+
 def FeatureNEON : SubtargetFeature<"neon", "HasNEON", "true",
-  "Enable Advanced SIMD instructions">;
+  "Enable Advanced SIMD instructions", [FeatureFPARMv8]>;
 
 def FeatureCrypto : SubtargetFeature<"crypto", "HasCrypto", "true",
   "Enable cryptographic instructions">;
@@ -33,7 +36,8 @@ def FeatureCrypto : SubtargetFeature<"crypto", "HasCrypto", "true",
 
 include "AArch64Schedule.td"
 
-def : Processor<"generic", GenericItineraries, [FeatureNEON, FeatureCrypto]>;
+def : Processor<"generic", GenericItineraries,
+                [FeatureFPARMv8, FeatureNEON, FeatureCrypto]>;
 
 //===----------------------------------------------------------------------===//
 // Register File Description
diff --git a/lib/Target/AArch64/AArch64ISelLowering.cpp b/lib/Target/AArch64/AArch64ISelLowering.cpp
index 87bb847993..323acdd01d 100644
--- a/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -50,10 +50,13 @@ AArch64TargetLowering::AArch64TargetLowering(AArch64TargetMachine &TM)
   // Scalar register <-> type mapping
   addRegisterClass(MVT::i32, &AArch64::GPR32RegClass);
   addRegisterClass(MVT::i64, &AArch64::GPR64RegClass);
-  addRegisterClass(MVT::f16, &AArch64::FPR16RegClass);
-  addRegisterClass(MVT::f32, &AArch64::FPR32RegClass);
-  addRegisterClass(MVT::f64, &AArch64::FPR64RegClass);
-  addRegisterClass(MVT::f128, &AArch64::FPR128RegClass);
+
+  if (Subtarget->hasFPARMv8()) {
+    addRegisterClass(MVT::f16, &AArch64::FPR16RegClass);
+    addRegisterClass(MVT::f32, &AArch64::FPR32RegClass);
+    addRegisterClass(MVT::f64, &AArch64::FPR64RegClass);
+    addRegisterClass(MVT::f128, &AArch64::FPR128RegClass);
+  }
 
   if (Subtarget->hasNEON()) {
     // And the vectors
@@ -961,24 +964,31 @@ AArch64TargetLowering::SaveVarArgRegisters(CCState &CCInfo, SelectionDAG &DAG,
     }
   }
 
+  if (getSubtarget()->hasFPARMv8()) {
   unsigned FPRSaveSize = 16 * (NumFPRArgRegs - FirstVariadicFPR);
   int FPRIdx = 0;
-  if (FPRSaveSize != 0) {
-    FPRIdx = MFI->CreateStackObject(FPRSaveSize, 16, false);
-
-    SDValue FIN = DAG.getFrameIndex(FPRIdx, getPointerTy());
-
-    for (unsigned i = FirstVariadicFPR; i < NumFPRArgRegs; ++i) {
-      unsigned VReg = MF.addLiveIn(AArch64FPRArgRegs[i],
-                                   &AArch64::FPR128RegClass);
-      SDValue Val = DAG.getCopyFromReg(Chain, DL, VReg, MVT::f128);
-      SDValue Store = DAG.getStore(Val.getValue(1), DL, Val, FIN,
-                                   MachinePointerInfo::getStack(i * 16),
-                                   false, false, 0);
-      MemOps.push_back(Store);
-      FIN = DAG.getNode(ISD::ADD, DL, getPointerTy(), FIN,
-                        DAG.getConstant(16, getPointerTy()));
+    // According to the AArch64 Procedure Call Standard, section B.1/B.3, we
+    // can omit a register save area if we know we'll never use registers of
+    // that class.
+    if (FPRSaveSize != 0) {
+      FPRIdx = MFI->CreateStackObject(FPRSaveSize, 16, false);
+
+      SDValue FIN = DAG.getFrameIndex(FPRIdx, getPointerTy());
+
+      for (unsigned i = FirstVariadicFPR; i < NumFPRArgRegs; ++i) {
+        unsigned VReg = MF.addLiveIn(AArch64FPRArgRegs[i],
+            &AArch64::FPR128RegClass);
+        SDValue Val = DAG.getCopyFromReg(Chain, DL, VReg, MVT::f128);
+        SDValue Store = DAG.getStore(Val.getValue(1), DL, Val, FIN,
+            MachinePointerInfo::getStack(i * 16),
+            false, false, 0);
+        MemOps.push_back(Store);
+        FIN = DAG.getNode(ISD::ADD, DL, getPointerTy(), FIN,
+            DAG.getConstant(16, getPointerTy()));
+      }
     }
+    FuncInfo->setVariadicFPRIdx(FPRIdx);
+    FuncInfo->setVariadicFPRSize(FPRSaveSize);
   }
 
   int StackIdx = MFI->CreateFixedObject(8, CCInfo.getNextStackOffset(), true);
@@ -986,8 +996,6 @@ AArch64TargetLowering::SaveVarArgRegisters(CCState &CCInfo, SelectionDAG &DAG,
   FuncInfo->setVariadicStackIdx(StackIdx);
   FuncInfo->setVariadicGPRIdx(GPRIdx);
   FuncInfo->setVariadicGPRSize(GPRSaveSize);
-  FuncInfo->setVariadicFPRIdx(FPRIdx);
-  FuncInfo->setVariadicFPRSize(FPRSaveSize);
 
   if (!MemOps.empty()) {
     Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, &MemOps[0],
diff --git a/lib/Target/AArch64/AArch64InstrFormats.td b/lib/Target/AArch64/AArch64InstrFormats.td
index d69db317fd..7a41ce05a1 100644
--- a/lib/Target/AArch64/AArch64InstrFormats.td
+++ b/lib/Target/AArch64/AArch64InstrFormats.td
@@ -383,6 +383,8 @@ class A64I_extract<bit sf, bits<3> op, bit n,
   // Inherits Rd in 4-0
 }
 
+let Predicates = [HasFPARMv8] in {
+
 // Format for floating-point compare instructions.
 class A64I_fpcmp<bit m, bit s, bits<2> type, bits<2> op, bits<5> opcode2,
                 dag outs, dag ins, string asmstr,
@@ -562,6 +564,8 @@ class A64I_fpimm<bit m, bit s, bits<2> type, bits<5> imm5,
   // Inherit Rd in 4-0
 }
 
+}
+
 // Format for load-register (literal) instructions.
 class A64I_LDRlit<bits<2> opc, bit v,
                   dag outs, dag ins, string asmstr,
diff --git a/lib/Target/AArch64/AArch64InstrInfo.td b/lib/Target/AArch64/AArch64InstrInfo.td
index 43df2b4362..ae217f9d4f 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/lib/Target/AArch64/AArch64InstrInfo.td
@@ -14,6 +14,8 @@
 //===----------------------------------------------------------------------===//
 // ARM Instruction Predicate Definitions.
 //
+def HasFPARMv8       : Predicate<"Subtarget->hasFPARMv8()">,
+                               AssemblerPredicate<"FeatureFPARMv8", "fp-armv8">;
 def HasNEON          : Predicate<"Subtarget->hasNEON()">,
                                  AssemblerPredicate<"FeatureNEON", "neon">;
 def HasCrypto        : Predicate<"Subtarget->hasCrypto()">,
@@ -2195,7 +2197,7 @@ def FNMSUBdddd : A64I_fpdp3Impl<"fnmsub", FPR64, f64, 0b01, 0b1, 0b1, fnmsub>;
 
 // Extra patterns for when we're allowed to optimise separate multiplication and
 // addition.
-let Predicates = [UseFusedMAC] in {
+let Predicates = [HasFPARMv8, UseFusedMAC] in {
 def : Pat<(f32 (fadd FPR32:$Ra, (f32 (fmul FPR32:$Rn, FPR32:$Rm)))),
           (FMADDssss FPR32:$Rn, FPR32:$Rm, FPR32:$Ra)>;
 def : Pat<(f32 (fsub FPR32:$Ra, (f32 (fmul FPR32:$Rn, FPR32:$Rm)))),
@@ -2351,6 +2353,7 @@ defm FCVTM : A64I_fptointRM<0b10, 0b0, "fcvtm">;
 defm FCVTZ : A64I_fptointRM<0b11, 0b0, "fcvtz">;
 defm FCVTA : A64I_fptointRM<0b00, 0b1, "fcvta">;
 
+let Predicates = [HasFPARMv8] in {
 def : Pat<(i32 (fp_to_sint f32:$Rn)), (FCVTZSws $Rn)>;
 def : Pat<(i64 (fp_to_sint f32:$Rn)), (FCVTZSxs $Rn)>;
 def : Pat<(i32 (fp_to_uint f32:$Rn)), (FCVTZUws $Rn)>;
@@ -2359,6 +2362,7 @@ def : Pat<(i32 (fp_to_sint f64:$Rn)), (FCVTZSwd $Rn)>;
 def : Pat<(i64 (fp_to_sint f64:$Rn)), (FCVTZSxd $Rn)>;
 def : Pat<(i32 (fp_to_uint f64:$Rn)), (FCVTZUwd $Rn)>;
 def : Pat<(i64 (fp_to_uint f64:$Rn)), (FCVTZUxd $Rn)>;
+}
 
 multiclass A64I_inttofp<bit o0, string asmop> {
   def CVTFsw : A64I_fpintI<0b0, 0b00, 0b00, {0, 1, o0}, FPR32, GPR32, asmop>;
@@ -2370,6 +2374,7 @@ multiclass A64I_inttofp<bit o0, string asmop> {
 defm S : A64I_inttofp<0b0, "scvtf">;
 defm U : A64I_inttofp<0b1, "ucvtf">;
 
+let Predicates = [HasFPARMv8] in {
 def : Pat<(f32 (sint_to_fp i32:$Rn)), (SCVTFsw $Rn)>;
 def : Pat<(f32 (sint_to_fp i64:$Rn)), (SCVTFsx $Rn)>;
 def : Pat<(f64 (sint_to_fp i32:$Rn)), (SCVTFdw $Rn)>;
@@ -2378,16 +2383,19 @@ def : Pat<(f32 (uint_to_fp i32:$Rn)), (UCVTFsw $Rn)>;
 def : Pat<(f32 (uint_to_fp i64:$Rn)), (UCVTFsx $Rn)>;
 def : Pat<(f64 (uint_to_fp i32:$Rn)), (UCVTFdw $Rn)>;
 def : Pat<(f64 (uint_to_fp i64:$Rn)), (UCVTFdx $Rn)>;
+}
 
 def FMOVws : A64I_fpintI<0b0, 0b00, 0b00, 0b110, GPR32, FPR32, "fmov">;
 def FMOVsw : A64I_fpintI<0b0, 0b00, 0b00, 0b111, FPR32, GPR32, "fmov">;
 def FMOVxd : A64I_fpintI<0b1, 0b01, 0b00, 0b110, GPR64, FPR64, "fmov">;
 def FMOVdx : A64I_fpintI<0b1, 0b01, 0b00, 0b111, FPR64, GPR64, "fmov">;
 
+let Predicates = [HasFPARMv8] in {
 def : Pat<(i32 (bitconvert f32:$Rn)), (FMOVws $Rn)>;
 def : Pat<(f32 (bitconvert i32:$Rn)), (FMOVsw $Rn)>;
 def : Pat<(i64 (bitconvert f64:$Rn)), (FMOVxd $Rn)>;
 def : Pat<(f64 (bitconvert i64:$Rn)), (FMOVdx $Rn)>;
+}
 
 def lane1_asmoperand : AsmOperandClass {
   let Name = "Lane1";
@@ -2410,11 +2418,13 @@ let DecoderMethod =  "DecodeFMOVLaneInstruction" in {
                           "fmov\t$Rd.d[$Lane], $Rn", [], NoItinerary>;
 }
 
+let Predicates = [HasFPARMv8] in {
 def : InstAlias<"fmov $Rd, $Rn.2d[$Lane]",
                 (FMOVxv GPR64:$Rd, VPR128:$Rn, lane1:$Lane), 0b0>;
 
 def : InstAlias<"fmov $Rd.2d[$Lane], $Rn",
                 (FMOVvx VPR128:$Rd, GPR64:$Rn, lane1:$Lane), 0b0>;
+}
 
 //===----------------------------------------------------------------------===//
 // Floating-point immediate instructions
@@ -2508,11 +2518,15 @@ let mayLoad = 1 in {
   def LDRx_lit : A64I_LDRlitSimple<0b01, 0b0, GPR64>;
 }
 
+let Predicates = [HasFPARMv8] in {
 def LDRs_lit  : A64I_LDRlitSimple<0b00, 0b1, FPR32>;
 def LDRd_lit  : A64I_LDRlitSimple<0b01, 0b1, FPR64>;
+}
 
 let mayLoad = 1 in {
+  let Predicates = [HasFPARMv8] in {
   def LDRq_lit : A64I_LDRlitSimple<0b10, 0b1, FPR128>;
+  }
 
 
   def LDRSWx_lit : A64I_LDRlit<0b10, 0b0,
@@ -3106,6 +3120,7 @@ defm LS32
 defm LS64
   : A64I_LDRSTR_unsigned<"LS64", 0b11, 0b0, 0b0, "", GPR64, dword_addrparams>;
 
+let Predicates = [HasFPARMv8] in {
 // STR/LDR to/from a B register
 defm LSFP8
   : A64I_LDRSTR_unsigned<"LSFP8", 0b00, 0b1, 0b0, "", FPR8, byte_addrparams>;
@@ -3124,6 +3139,7 @@ defm LSFP64
 defm LSFP128
   : A64I_LDRSTR_unsigned<"LSFP128", 0b00, 0b1, 0b1, "", FPR128,
                          qword_addrparams>;
+}
 
 //===------------------------------
 // 2.3 Signed loads
@@ -3579,10 +3595,13 @@ multiclass A64I_LSPsimple<bits<2> opc, bit v, RegisterClass SomeReg,
 
 defm LSPair32 : A64I_LSPsimple<0b00, 0b0, GPR32, word_simm7, "LSPair32">;
 defm LSPair64 : A64I_LSPsimple<0b10, 0b0, GPR64, dword_simm7, "LSPair64">;
+
+let Predicates = [HasFPARMv8] in {
 defm LSFPPair32 : A64I_LSPsimple<0b00, 0b1, FPR32, word_simm7, "LSFPPair32">;
 defm LSFPPair64 : A64I_LSPsimple<0b01, 0b1, FPR64,  dword_simm7, "LSFPPair64">;
 defm LSFPPair128 : A64I_LSPsimple<0b10, 0b1, FPR128, qword_simm7,
                                   "LSFPPair128">;
+}
 
 
 def LDPSWx : A64I_LSPoffset<0b01, 0b0, 0b1,
diff --git a/lib/Target/AArch64/AArch64Subtarget.cpp b/lib/Target/AArch64/AArch64Subtarget.cpp
index d71bb4e973..eece389302 100644
--- a/lib/Target/AArch64/AArch64Subtarget.cpp
+++ b/lib/Target/AArch64/AArch64Subtarget.cpp
@@ -26,10 +26,27 @@
 using namespace llvm;
 
 AArch64Subtarget::AArch64Subtarget(StringRef TT, StringRef CPU, StringRef FS)
-    : AArch64GenSubtargetInfo(TT, CPU, FS), HasNEON(false), HasCrypto(false),
-      TargetTriple(TT) {
+    : AArch64GenSubtargetInfo(TT, CPU, FS), HasFPARMv8(false), HasNEON(false),
+      HasCrypto(false), TargetTriple(TT), CPUString(CPU) {
 
-  ParseSubtargetFeatures(CPU, FS);
+  initializeSubtargetFeatures(CPU, FS);
+}
+
+void AArch64Subtarget::initializeSubtargetFeatures(StringRef CPU,
+                                                   StringRef FS) {
+  if (CPU.empty())
+    CPUString = "generic";
+
+  std::string FullFS = FS;
+  if (CPUString == "generic") {
+    // Enable FP by default.
+    if (FullFS.empty())
+      FullFS = "+fp-armv8";
+    else
+      FullFS = "+fp-armv8," + FullFS;
+  }
+
+  ParseSubtargetFeatures(CPU, FullFS);
 }
 
 bool AArch64Subtarget::GVIsIndirectSymbol(const GlobalValue *GV,
diff --git a/lib/Target/AArch64/AArch64Subtarget.h b/lib/Target/AArch64/AArch64Subtarget.h
index f262b94617..57eb187c9d 100644
--- a/lib/Target/AArch64/AArch64Subtarget.h
+++ b/lib/Target/AArch64/AArch64Subtarget.h
@@ -28,11 +28,19 @@ class GlobalValue;
 
 class AArch64Subtarget : public AArch64GenSubtargetInfo {
 protected:
+  bool HasFPARMv8;
   bool HasNEON;
   bool HasCrypto;
 
   /// TargetTriple - What processor and OS we're targeting.
   Triple TargetTriple;
+
+  /// CPUString - String name of used CPU.
+  std::string CPUString;
+
+private:
+  void initializeSubtargetFeatures(StringRef CPU, StringRef FS);
+
 public:
   /// This constructor initializes the data members to match that
   /// of the specified triple.
@@ -52,9 +60,11 @@ public:
   bool isTargetELF() const { return TargetTriple.isOSBinFormatELF(); }
   bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
 
+  bool hasFPARMv8() const { return HasFPARMv8; }
   bool hasNEON() const { return HasNEON; }
-
   bool hasCrypto() const { return HasCrypto; }
+
+  const std::string & getCPUString() const { return CPUString; }
 };
 } // End llvm namespace