ARM: add cyclone CPU with ZeroCycleZeroing feature.

The Cyclone CPU is similar to swift for most LLVM purposes, but does have two
preferred instructions for zeroing a VFP register. This teaches LLVM about
them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205309 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 45 insertions, 6 deletions

diff --git a/lib/Target/ARM/ARM.td b/lib/Target/ARM/ARM.td
index 27bbcc22b6..7916ccc180 100644
--- a/lib/Target/ARM/ARM.td
+++ b/lib/Target/ARM/ARM.td
@@ -73,6 +73,11 @@ def FeatureCrypto : SubtargetFeature<"crypto", "HasCrypto", "true",
 def FeatureCRC : SubtargetFeature<"crc", "HasCRC", "true",
                           "Enable support for CRC instructions">;
 
+// Cyclone has preferred instructions for zeroing VFP registers, which can
+// execute in 0 cycles.
+def FeatureZCZeroing : SubtargetFeature<"zcz", "HasZeroCycleZeroing", "true",
+                                        "Has zero-cycle zeroing instructions">;
+
 // Some processors have FP multiply-accumulate instructions that don't
 // play nicely with other VFP / NEON instructions, and it's generally better
 // to just not use them.
@@ -361,6 +366,13 @@ def : ProcessorModel<"cortex-a15",   CortexA9Model,
                                      FeatureDSPThumb2, FeatureHasRAS,
                                      FeatureAClass]>;
 
+// FIXME: krait has currently the same Schedule model as A9
+def : ProcessorModel<"krait",       CortexA9Model,
+                                    [ProcKrait, HasV7Ops,
+                                     FeatureNEON, FeatureDB,
+                                     FeatureDSPThumb2, FeatureHasRAS,
+                                     FeatureAClass]>;
+
 // FIXME: R5 has currently the same ProcessorModel as A8.
 def : ProcessorModel<"cortex-r5",   CortexA8Model,
                                     [ProcR5, HasV7Ops, FeatureDB,
@@ -395,12 +407,12 @@ def : ProcNoItin<"cortex-a57",      [ProcA57, HasV8Ops, FeatureAClass,
                                     FeatureDB, FeatureFPARMv8,
                                     FeatureNEON, FeatureDSPThumb2]>;
 
-// FIXME: krait has currently the same Schedule model as A9
-def : ProcessorModel<"krait",       CortexA9Model,
-                                    [ProcKrait, HasV7Ops,
-                                     FeatureNEON, FeatureDB,
-                                     FeatureDSPThumb2, FeatureHasRAS,
-                                     FeatureAClass]>;
+// Cyclone is very similar to swift
+def : ProcessorModel<"cyclone",     SwiftModel,
+                                    [ProcSwift, HasV8Ops, HasV7Ops,
+                                     FeatureCrypto, FeatureFPARMv8,
+                                     FeatureDB,FeatureDSPThumb2,
+                                     FeatureHasRAS, FeatureZCZeroing]>;
 
 //===----------------------------------------------------------------------===//
 // Register File Description
diff --git a/lib/Target/ARM/ARMInstrInfo.td b/lib/Target/ARM/ARMInstrInfo.td
index cc748e19c8..dfcc11edcd 100644
--- a/lib/Target/ARM/ARMInstrInfo.td
+++ b/lib/Target/ARM/ARMInstrInfo.td
@@ -244,6 +244,7 @@ def HasMP            : Predicate<"Subtarget->hasMPExtension()">,
 def HasTrustZone     : Predicate<"Subtarget->hasTrustZone()">,
                                  AssemblerPredicate<"FeatureTrustZone",
                                                     "TrustZone">;
+def HasZCZ           : Predicate<"Subtarget->hasZeroCycleZeroing()">;
 def UseNEONForFP     : Predicate<"Subtarget->useNEONForSinglePrecisionFP()">;
 def DontUseNEONForFP : Predicate<"!Subtarget->useNEONForSinglePrecisionFP()">;
 def IsThumb          : Predicate<"Subtarget->isThumb()">,
diff --git a/lib/Target/ARM/ARMInstrNEON.td b/lib/Target/ARM/ARMInstrNEON.td
index b18eac55d8..0d46c49bcf 100644
--- a/lib/Target/ARM/ARMInstrNEON.td
+++ b/lib/Target/ARM/ARMInstrNEON.td
@@ -5245,6 +5245,26 @@ def VMOVv4f32 : N1ModImm<1, 0b000, 0b1111, 0, 1, 0, 1, (outs QPR:$Vd),
                          [(set QPR:$Vd, (v4f32 (NEONvmovFPImm timm:$SIMM)))]>;
 } // isReMaterializable
 
+
+// On some CPUs the two instructions "vmov.i32 dD, #0" and "vmov.i32 qD, #0"
+// require zero cycles to execute so they should be used wherever possible for
+// setting a register to zero.
+
+// Even without these pseudo-insts we would probably end up with the correct
+// instruction, but we could not mark the general ones with "isAsCheapAsAMove"
+// since they are sometimes rather expensive (in general).
+
+let AddedComplexity = 50, isAsCheapAsAMove = 1, isReMaterializable = 1 in {
+  def VMOVD0 : ARMPseudoExpand<(outs DPR:$Vd), (ins), 4, IIC_VMOVImm,
+                               [(set DPR:$Vd, (v2i32 NEONimmAllZerosV))],
+                               (VMOVv2i32 DPR:$Vd, 0, (ops 14, zero_reg))>,
+               Requires<[HasZCZ]>;
+  def VMOVQ0 : ARMPseudoExpand<(outs QPR:$Vd), (ins), 4, IIC_VMOVImm,
+                               [(set QPR:$Vd, (v4i32 NEONimmAllZerosV))],
+                               (VMOVv4i32 QPR:$Vd, 0, (ops 14, zero_reg))>,
+               Requires<[HasZCZ]>;
+}
+
 //   VMOV     : Vector Get Lane (move scalar to ARM core register)
 
 def VGETLNs8  : NVGetLane<{1,1,1,0,0,1,?,1}, 0b1011, {?,?},
diff --git a/lib/Target/ARM/ARMSubtarget.cpp b/lib/Target/ARM/ARMSubtarget.cpp
index a290136f6b..0dec1c406a 100644
--- a/lib/Target/ARM/ARMSubtarget.cpp
+++ b/lib/Target/ARM/ARMSubtarget.cpp
@@ -134,6 +134,7 @@ void ARMSubtarget::initializeEnvironment() {
   HasTrustZone = false;
   HasCrypto = false;
   HasCRC = false;
+  HasZeroCycleZeroing = false;
   AllowsUnalignedMem = false;
   Thumb2DSP = false;
   UseNaClTrap = false;
diff --git a/lib/Target/ARM/ARMSubtarget.h b/lib/Target/ARM/ARMSubtarget.h
index 2ce99c890f..e76cc85a1a 100644
--- a/lib/Target/ARM/ARMSubtarget.h
+++ b/lib/Target/ARM/ARMSubtarget.h
@@ -177,6 +177,10 @@ protected:
   /// HasCRC - if true, processor supports CRC instructions
   bool HasCRC;
 
+  /// If true, the instructions "vmov.i32 d0, #0" and "vmov.i32 q0, #0" are
+  /// particularly effective at zeroing a VFP register.
+  bool HasZeroCycleZeroing;
+
   /// AllowsUnalignedMem - If true, the subtarget allows unaligned memory
   /// accesses for some types.  For details, see
   /// ARMTargetLowering::allowsUnalignedMemoryAccesses().
@@ -298,6 +302,7 @@ public:
   bool isFPOnlySP() const { return FPOnlySP; }
   bool hasPerfMon() const { return HasPerfMon; }
   bool hasTrustZone() const { return HasTrustZone; }
+  bool hasZeroCycleZeroing() const { return HasZeroCycleZeroing; }
   bool prefers32BitThumb() const { return Pref32BitThumb; }
   bool avoidCPSRPartialUpdate() const { return AvoidCPSRPartialUpdate; }
   bool avoidMOVsShifterOperand() const { return AvoidMOVsShifterOperand; }