[x86] Introduce the pconfig instruction

[craig.topper]

Disassembler test?

[craig.topper]

LGTM

lib/Support/Host.cpp

bool sys::getHostCPUFeatures(StringMap<bool> &Features) {
   Features["avx512vpopcntdq"] = HasLeaf7 && ((ECX >> 14) & 1) && HasAVX512Save;
   Features["rdpid"]           = HasLeaf7 && ((ECX >> 22) & 1);
   Features["cldemote"]        = HasLeaf7 && ((ECX >> 25) & 1);
   Features["movdiri"]         = HasLeaf7 && ((ECX >> 27) & 1);
   Features["movdir64b"]       = HasLeaf7 && ((ECX >> 28) & 1);
 
   Features["ibt"] = HasLeaf7 && ((EDX >> 20) & 1);
 
+  // There are two CPUID leafs which information associated with the pconfig
+  // instruction:
+  // EAX=0x7, ECX=0x0 indicates the availability of the instruction (via the 18th
+  // bit of EDX), while the EAX=0x1b leaf returns information on the
+  // availability of specific pconfig leafs.
+  // The target feature here only refers to the the first of these two.
+  // Users might need to check for the availability of specific pconfig
+  // leaves using cpuid, since that information is ignored while
+  // detecting features using the "-march=native" flag.
+  // For more info, see X86 ISA docs.
+  Features["pconfig"] = HasLeaf7 && ((EDX >> 18) & 1);
+
   bool HasLeafD = MaxLevel >= 0xd &&
                   !getX86CpuIDAndInfoEx(0xd, 0x1, &EAX, &EBX, &ECX, &EDX);
 
   // Only enable XSAVE if OS has enabled support for saving YMM state.
   Features["xsaveopt"] = HasLeafD && ((EAX >> 0) & 1) && HasAVXSave;
   Features["xsavec"]   = HasLeafD && ((EAX >> 1) & 1) && HasAVXSave;
   Features["xsaves"]   = HasLeafD && ((EAX >> 3) & 1) && HasAVXSave;
 

lib/Target/X86/X86.td

def FeatureSoftFloat
     : SubtargetFeature<"soft-float", "UseSoftFloat", "true",
                        "Use software floating point features.">;
 def FeaturePOPCNTFalseDeps : SubtargetFeature<"false-deps-popcnt",
                                      "HasPOPCNTFalseDeps", "true",
                                      "POPCNT has a false dependency on dest register">;
 def FeatureLZCNTFalseDeps : SubtargetFeature<"false-deps-lzcnt-tzcnt",
                                      "HasLZCNTFalseDeps", "true",
                                      "LZCNT/TZCNT have a false dependency on dest register">;
+def FeaturePCONFIG : SubtargetFeature<"pconfig", "HasPCONFIG", "true",
+                                      "platform configuration instruction">;
 // On recent X86 (port bound) processors, its preferable to combine to a single shuffle
 // using a variable mask over multiple fixed shuffles.
 def FeatureFastVariableShuffle
     : SubtargetFeature<"fast-variable-shuffle",
                        "HasFastVariableShuffle",
                        "true", "Shuffles with variable masks are fast">;
 // On some X86 processors, there is no performance hazard to writing only the
 // lower parts of a YMM or ZMM register without clearing the upper part.
class IcelakeClientProc<string Name> : ProcModel<Name, SkylakeServerModel,
   ProcIntelICL,
   FeatureHasFastGather
 ]>;
 def : IcelakeClientProc<"icelake-client">;
 
 class IcelakeServerProc<string Name> : ProcModel<Name, SkylakeServerModel,
                                                  ICLFeatures.Value, [
   ProcIntelICX,
+  FeaturePCONFIG,
   FeatureWBNOINVD,
   FeatureHasFastGather
 ]>;
 def : IcelakeServerProc<"icelake-server">;
 
 // AMD CPUs.
 
 def : Proc<"k6",              [FeatureX87, FeatureSlowUAMem16, FeatureMMX]>;

lib/Target/X86/X86InstrInfo.td

 def HasSHSTK     : Predicate<"Subtarget->hasSHSTK()">;
 def HasIBT       : Predicate<"Subtarget->hasIBT()">;
 def HasCLFLUSHOPT : Predicate<"Subtarget->hasCLFLUSHOPT()">;
 def HasCLWB      : Predicate<"Subtarget->hasCLWB()">;
 def HasWBNOINVD  : Predicate<"Subtarget->hasWBNOINVD()">;
 def HasRDPID     : Predicate<"Subtarget->hasRDPID()">;
 def HasWAITPKG   : Predicate<"Subtarget->hasWAITPKG()">;
 def HasCmpxchg16b: Predicate<"Subtarget->hasCmpxchg16b()">;
+def HasPCONFIG   : Predicate<"Subtarget->hasPCONFIG()">;
 def Not64BitMode : Predicate<"!Subtarget->is64Bit()">,
                              AssemblerPredicate<"!Mode64Bit", "Not 64-bit mode">;
 def In64BitMode  : Predicate<"Subtarget->is64Bit()">,
                              AssemblerPredicate<"Mode64Bit", "64-bit mode">;
 def IsLP64  : Predicate<"Subtarget->isTarget64BitLP64()">;
 def NotLP64 : Predicate<"!Subtarget->isTarget64BitLP64()">;
 def In16BitMode  : Predicate<"Subtarget->is16Bit()">,
                              AssemblerPredicate<"Mode16Bit", "16-bit mode">;

lib/Target/X86/X86InstrSystem.td

 def PTWRITE64m : RI<0xAE, MRM4m, (outs), (ins i64mem:$dst),
                     "ptwrite{q}\t$dst", []>, XS, Requires<[In64BitMode]>;
 
 def PTWRITEr : I<0xAE, MRM4r, (outs), (ins GR32:$dst),
                  "ptwrite{l}\t$dst", []>, XS;
 def PTWRITE64r : RI<0xAE, MRM4r, (outs), (ins GR64:$dst),
                     "ptwrite{q}\t$dst", []>, XS, Requires<[In64BitMode]>;
 } // SchedRW
+
+//===----------------------------------------------------------------------===//
+// Platform Configuration instruction
+
+// From ISA docs:
+//  "This instruction is used to execute functions for configuring platform
+//   features.
+//   EAX: Leaf function to be invoked.
+//   RBX/RCX/RDX: Leaf-specific purpose."
+//  "Successful execution of the leaf clears RAX (set to zero) and ZF, CF, PF,
+//   AF, OF, and SF are cleared. In case of failure, the failure reason is
+//   indicated in RAX with ZF set to 1 and CF, PF, AF, OF, and SF are cleared."
+// Thus all these mentioned registers are considered clobbered.
+
+let Uses = [RAX, RBX, RCX, RDX], Defs = [RAX, RBX, RCX, RDX, EFLAGS] in
+    def PCONFIG : I<0x01, MRM_C5, (outs), (ins), "pconfig", []>, TB,
+                  Requires<[HasPCONFIG]>;

lib/Target/X86/X86Subtarget.h

protected:
   bool HasWBNOINVD;
 
   /// Processor support RDPID instruction
   bool HasRDPID;
 
   /// Processor supports WaitPKG instructions
   bool HasWAITPKG;
 
+  /// Processor supports PCONFIG instruction
+  bool HasPCONFIG;
+
   /// Use a retpoline thunk rather than indirect calls to block speculative
   /// execution.
   bool UseRetpoline;
 
   /// When using a retpoline thunk, call an externally provided thunk rather
   /// than emitting one inside the compiler.
   bool UseRetpolineExternalThunk;
 
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 hasPCONFIG() const { return HasPCONFIG; }
   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.

lib/Target/X86/X86Subtarget.cpp

void X86Subtarget::initializeEnvironment() {
   HasCLZERO = false;
   HasCLDEMOTE = false;
   HasMOVDIRI = false;
   HasMOVDIR64B = false;
   HasMPX = false;
   HasSHSTK = false;
   HasIBT = false;
   HasSGX = false;
+  HasPCONFIG = false;
   HasCLFLUSHOPT = false;
   HasCLWB = false;
   HasWBNOINVD = false;
   HasRDPID = false;
   HasWAITPKG = false;
   UseRetpoline = false;
   UseRetpolineExternalThunk = false;
   IsPMULLDSlow = false;

test/MC/X86/x86-32-coverage.s

 
 // CHECK: movdir64b (%esi), %eax
 // CHECK: # encoding: [0x66,0x0f,0x38,0xf8,0x06]
           movdir64b (%esi), %eax
 
 // CHECK: movdir64b (%si), %ax
 // CHECK: # encoding: [0x67,0x66,0x0f,0x38,0xf8,0x04]
           movdir64b (%si), %ax
+
+// CHECK: pconfig
+// CHECK:  encoding: [0x0f,0x01,0xc5]
+  pconfig

test/MC/X86/x86-64.s

 // CHECK: movdir64b 485498096, %eax
 // CHECK: # encoding: [0x67,0x66,0x0f,0x38,0xf8,0x04,0x25,0xf0,0x1c,0xf0,0x1c]
 movdir64b 485498096, %eax
 
 // CHECK: movdir64b (%rdx), %r15
 // CHECK: # encoding: [0x66,0x44,0x0f,0x38,0xf8,0x3a]
 movdir64b (%rdx), %r15
 
+// CHECK: pconfig
+// CHECK:  encoding: [0x0f,0x01,0xc5]
+pconfig
+
 //  __asm __volatile(
 //    "pushf        \n\t"
 //    "popf       \n\t"
 //    "rep        \n\t"
 //    ".byte  0x0f, 0xa7, 0xd0"
 //  );
 // CHECK: pushfq
 // CHECK-NEXT: popfq