[x86] Introduce the enclv instruction

[GBuella]

Summary

and use the -msgx flag as a requirement
for the SGX instructions.

[craig.topper]

Disassembler test?

[craig.topper]

LGTM

lib/Target/X86/X86InstrInfo.td

 def HasBMI2      : Predicate<"Subtarget->hasBMI2()">;
 def NoBMI2       : Predicate<"!Subtarget->hasBMI2()">;
 def HasVBMI      : Predicate<"Subtarget->hasVBMI()">;
 def HasVBMI2     : Predicate<"Subtarget->hasVBMI2()">;
 def HasIFMA      : Predicate<"Subtarget->hasIFMA()">;
 def HasRTM       : Predicate<"Subtarget->hasRTM()">;
 def HasADX       : Predicate<"Subtarget->hasADX()">;
 def HasSHA       : Predicate<"Subtarget->hasSHA()">;
+def HasSGX       : Predicate<"Subtarget->hasSGX()">;
 def HasPRFCHW    : Predicate<"Subtarget->hasPRFCHW()">;
 def HasRDSEED    : Predicate<"Subtarget->hasRDSEED()">;
 def HasSSEPrefetch : Predicate<"Subtarget->hasSSEPrefetch()">;
 def NoSSEPrefetch : Predicate<"!Subtarget->hasSSEPrefetch()">;
 def HasPrefetchW : Predicate<"Subtarget->hasPRFCHW()">;
 def HasPREFETCHWT1 : Predicate<"Subtarget->hasPREFETCHWT1()">;
 def HasLAHFSAHF  : Predicate<"Subtarget->hasLAHFSAHF()">;
 def HasMWAITX    : Predicate<"Subtarget->hasMWAITX()">;

lib/Target/X86/X86InstrSGX.td

 // This file describes the instructions that make up the Intel SGX instruction
 // set.
 //
 //===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 // SGX instructions
 
-let SchedRW = [WriteSystem] in {
+let SchedRW = [WriteSystem], Predicates = [HasSGX] in {
 // ENCLS - Execute an Enclave System Function of Specified Leaf Number
 def ENCLS : I<0x01, MRM_CF, (outs), (ins),
              "encls", []>, TB;
 
 // ENCLU - Execute an Enclave User Function of Specified Leaf Number
 def ENCLU : I<0x01, MRM_D7, (outs), (ins),
              "enclu", []>, TB;
+
+// ENCLV - Execute an Enclave VMM Function of Specified Leaf Number
+def ENCLV : I<0x01, MRM_C0, (outs), (ins),
+             "enclv", []>, TB;
 } // SchedRW

lib/Target/X86/X86Subtarget.h

public:
   bool hasMPX() const { return HasMPX; }
   bool hasSHSTK() const { return HasSHSTK; }
   bool hasIBT() const { return HasIBT; }
   bool hasCLFLUSHOPT() const { return HasCLFLUSHOPT; }
   bool hasCLWB() const { return HasCLWB; }
   bool hasWBNOINVD() const { return HasWBNOINVD; }
   bool hasRDPID() const { return HasRDPID; }
   bool hasWAITPKG() const { return HasWAITPKG; }
+  bool hasSGX() const { return HasSGX; }
   bool useRetpoline() const { return UseRetpoline; }
   bool useRetpolineExternalThunk() const { return UseRetpolineExternalThunk; }
 
   unsigned getPreferVectorWidth() const { return PreferVectorWidth; }
   unsigned getRequiredVectorWidth() const { return RequiredVectorWidth; }
 
   // Helper functions to determine when we should allow widening to 512-bit
   // during codegen.

test/MC/X86/sgx-encoding.s

 // RUN: llvm-mc -triple x86_64-unknown-unknown --show-encoding %s | FileCheck %s
+// RUN: llvm-mc -triple i386 --show-encoding %s | FileCheck %s
 
 // CHECK: encls
 // CHECK: encoding: [0x0f,0x01,0xcf]
   encls
 
 // CHECK: enclu
 // CHECK: encoding: [0x0f,0x01,0xd7]
   enclu
+
+// CHECK: enclv
+// CHECK: encoding: [0x0f,0x01,0xc0]
+  enclv