[AArch64] Refactor LSE support as feature separate from V8.1a support.

Summary:
This is preparation for ThunderX processors that have Large
System Extension (LSE) atomic instructions, but not the 
other instructions introduced by V8.1a.
This will mimic changes to GCC as described here:
https://gcc.gnu.org/ml/gcc-patches/2015-06/msg00388.html

LSE instructions are: LD/ST<op>, CAS*, SWP

Reviewers: t.p.northover, echristo, jmolloy, rengolin

Subscribers: aemerson, mehdi_amini

Differential Revision: https://reviews.llvm.org/D26621

llvm-svn: 288279

5 files changed, 16 insertions, 6 deletions

diff --git a/llvm/lib/Target/AArch64/AArch64.td b/llvm/lib/Target/AArch64/AArch64.td
index c6afa552ecf..65d5e8fe1f2 100644
--- a/llvm/lib/Target/AArch64/AArch64.td
+++ b/llvm/lib/Target/AArch64/AArch64.td
@@ -35,6 +35,9 @@ def FeatureCRC : SubtargetFeature<"crc", "HasCRC", "true",
 def FeatureRAS : SubtargetFeature<"ras", "HasRAS", "true",
   "Enable ARMv8 Reliability, Availability and Serviceability Extensions">;
 
+def FeatureLSE : SubtargetFeature<"lse", "HasLSE", "true",
+  "Enable ARMv8.1 Large System Extension (LSE) atomic instructions">;
+
 def FeaturePerfMon : SubtargetFeature<"perfmon", "HasPerfMon", "true",
   "Enable ARMv8 PMUv3 Performance Monitors extension">;
 
@@ -111,7 +114,7 @@ def FeatureUseRSqrt : SubtargetFeature<
 //
 
 def HasV8_1aOps : SubtargetFeature<"v8.1a", "HasV8_1aOps", "true",
-  "Support ARM v8.1a instructions", [FeatureCRC]>;
+  "Support ARM v8.1a instructions", [FeatureCRC, FeatureLSE]>;
 
 def HasV8_2aOps : SubtargetFeature<"v8.2a", "HasV8_2aOps", "true",
   "Support ARM v8.2a instructions", [HasV8_1aOps, FeatureRAS]>;
diff --git a/llvm/lib/Target/AArch64/AArch64InstrFormats.td b/llvm/lib/Target/AArch64/AArch64InstrFormats.td
index d6617617381..cefdf51b50d 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrFormats.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrFormats.td
@@ -9348,7 +9348,7 @@ class SHAInstSS<bits<4> opc, string asm, Intrinsic OpNode>
 // ST<OP>{<order>}[<size>] <Ws>, [<Xn|SP>]
 // ST<OP>{<order>} <Xs>, [<Xn|SP>]
 
-let Predicates = [HasV8_1a], mayLoad = 1, mayStore = 1, hasSideEffects = 1 in
+let Predicates = [HasLSE], mayLoad = 1, mayStore = 1, hasSideEffects = 1 in
 class BaseCASEncoding<dag oops, dag iops, string asm, string operands,
                       string cstr, list<dag> pattern>
       : I<oops, iops, asm, operands, cstr, pattern> {
@@ -9369,6 +9369,7 @@ class BaseCASEncoding<dag oops, dag iops, string asm, string operands,
   let Inst{14-10} = 0b11111;
   let Inst{9-5} = Rn;
   let Inst{4-0} = Rt;
+  let Predicates = [HasLSE];
 }
 
 class BaseCAS<string order, string size, RegisterClass RC>
@@ -9401,7 +9402,7 @@ multiclass CompareAndSwapPair<bits<1> Acq, bits<1> Rel, string order> {
     def d : BaseCASP<order, "", XSeqPairClassOperand>;
 }
 
-let Predicates = [HasV8_1a] in
+let Predicates = [HasLSE] in
 class BaseSWP<string order, string size, RegisterClass RC>
       : I<(outs RC:$Rt),(ins RC:$Rs, GPR64sp:$Rn), "swp" # order # size,
           "\t$Rs, $Rt, [$Rn]","",[]>,
@@ -9424,6 +9425,7 @@ class BaseSWP<string order, string size, RegisterClass RC>
   let Inst{11-10} = 0b00;
   let Inst{9-5} = Rn;
   let Inst{4-0} = Rt;
+  let Predicates = [HasLSE];
 }
 
 multiclass Swap<bits<1> Acq, bits<1> Rel, string order> {
@@ -9433,7 +9435,7 @@ multiclass Swap<bits<1> Acq, bits<1> Rel, string order> {
   let Sz = 0b11, Acq = Acq, Rel = Rel in def d : BaseSWP<order, "", GPR64>;
 }
 
-let Predicates = [HasV8_1a], mayLoad = 1, mayStore = 1, hasSideEffects = 1 in
+let Predicates = [HasLSE], mayLoad = 1, mayStore = 1, hasSideEffects = 1 in
 class BaseLDOPregister<string op, string order, string size, RegisterClass RC>
       : I<(outs RC:$Rt),(ins RC:$Rs, GPR64sp:$Rn), "ld" # op # order # size,
           "\t$Rs, $Rt, [$Rn]","",[]>,
@@ -9456,6 +9458,7 @@ class BaseLDOPregister<string op, string order, string size, RegisterClass RC>
   let Inst{11-10} = 0b00;
   let Inst{9-5} = Rn;
   let Inst{4-0} = Rt;
+  let Predicates = [HasLSE];
 }
 
 multiclass LDOPregister<bits<3> opc, string op, bits<1> Acq, bits<1> Rel, 
@@ -9470,7 +9473,7 @@ multiclass LDOPregister<bits<3> opc, string op, bits<1> Acq, bits<1> Rel,
     def d : BaseLDOPregister<op, order, "", GPR64>;
 }
 
-let Predicates = [HasV8_1a] in
+let Predicates = [HasLSE] in
 class BaseSTOPregister<string asm, RegisterClass OP, Register Reg,
                         Instruction inst> :
       InstAlias<asm # "\t$Rs, [$Rn]", (inst Reg, OP:$Rs, GPR64sp:$Rn)>;
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.td b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
index 3bed50016b4..c5b95f282ea 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
@@ -26,6 +26,8 @@ def HasCrypto        : Predicate<"Subtarget->hasCrypto()">,
                                  AssemblerPredicate<"FeatureCrypto", "crypto">;
 def HasCRC           : Predicate<"Subtarget->hasCRC()">,
                                  AssemblerPredicate<"FeatureCRC", "crc">;
+def HasLSE           : Predicate<"Subtarget->hasLSE()">,
+                                 AssemblerPredicate<"FeatureLSE", "lse">;
 def HasRAS           : Predicate<"Subtarget->hasRAS()">,
                                  AssemblerPredicate<"FeatureRAS", "ras">;
 def HasPerfMon       : Predicate<"Subtarget->hasPerfMon()">;
diff --git a/llvm/lib/Target/AArch64/AArch64Subtarget.h b/llvm/lib/Target/AArch64/AArch64Subtarget.h
index 5428c453d58..73f63b8b9f6 100644
--- a/llvm/lib/Target/AArch64/AArch64Subtarget.h
+++ b/llvm/lib/Target/AArch64/AArch64Subtarget.h
@@ -59,6 +59,7 @@ protected:
   bool HasNEON = false;
   bool HasCrypto = false;
   bool HasCRC = false;
+  bool HasLSE = false;
   bool HasRAS = false;
   bool HasPerfMon = false;
   bool HasFullFP16 = false;
@@ -180,6 +181,7 @@ public:
   bool hasNEON() const { return HasNEON; }
   bool hasCrypto() const { return HasCrypto; }
   bool hasCRC() const { return HasCRC; }
+  bool hasLSE() const { return HasLSE; }
   bool hasRAS() const { return HasRAS; }
   bool balanceFPOps() const { return BalanceFPOps; }
   bool predictableSelectIsExpensive() const {
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
index 36d3abbd44d..402b1e3e223 100644
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
@@ -4137,9 +4137,9 @@ static const struct {
   { "fp", {AArch64::FeatureFPARMv8} },
   { "simd", {AArch64::FeatureNEON} },
   { "ras", {AArch64::FeatureRAS} },
+  { "lse", {AArch64::FeatureLSE} },
 
   // FIXME: Unsupported extensions
-  { "lse", {} },
   { "pan", {} },
   { "lor", {} },
   { "rdma", {} },