[AArch64] Adding support for PMMIR_EL1 register

[vhscampos]

Summary

The PMMIR_EL1 register is present in Armv8.4 with PMU extension.
This patch adds support for it.

[dnsampaio]

Hi,
this seems mostly good, perhaps just missing a disassembler test, such as in llvm/test/MC/Disassembler/AArch64/armv8.4a-mpam.txt?

[vhscampos]

Added test into Disassembler

[dnsampaio]

LGTM. Could wait a day before committing in case anyone else has a say.

llvm/lib/Target/AArch64/AArch64.td

 def FeatureAM : SubtargetFeature<
     "am", "HasAM", "true",
     "Enable v8.4-A Activity Monitors extension">;
 
 def FeatureSEL2 : SubtargetFeature<
     "sel2", "HasSEL2", "true",
     "Enable v8.4-A Secure Exception Level 2 extension">;
 
+def FeaturePMU : SubtargetFeature<
+    "pmu", "HasPMU", "true",
+    "Enable v8.4-A PMU extension">;
+
 def FeatureTLB_RMI : SubtargetFeature<
     "tlb-rmi", "HasTLB_RMI", "true",
     "Enable v8.4-A TLB Range and Maintenance Instructions">;
 
 def FeatureFMI : SubtargetFeature<
     "fmi", "HasFMI", "true",
     "Enable v8.4-A Flag Manipulation Instructions">;
 

 
 def HasV8_3aOps : SubtargetFeature<"v8.3a", "HasV8_3aOps", "true",
   "Support ARM v8.3a instructions", [HasV8_2aOps, FeatureRCPC, FeaturePA,
   FeatureJS, FeatureCCIDX, FeatureComplxNum]>;
 
 def HasV8_4aOps : SubtargetFeature<"v8.4a", "HasV8_4aOps", "true",
   "Support ARM v8.4a instructions", [HasV8_3aOps, FeatureDotProd,
   FeatureNV, FeatureRASv8_4, FeatureMPAM, FeatureDIT,
-  FeatureTRACEV8_4, FeatureAM, FeatureSEL2, FeatureTLB_RMI,
+  FeatureTRACEV8_4, FeatureAM, FeatureSEL2, FeaturePMU, FeatureTLB_RMI,
   FeatureFMI, FeatureRCPC_IMMO]>;
 
 def HasV8_5aOps : SubtargetFeature<
   "v8.5a", "HasV8_5aOps", "true", "Support ARM v8.5a instructions",
   [HasV8_4aOps, FeatureAltFPCmp, FeatureFRInt3264, FeatureSpecRestrict,
    FeatureSSBS, FeatureSB, FeaturePredRes, FeatureCacheDeepPersist,
    FeatureBranchTargetId]
 >;

llvm/lib/Target/AArch64/AArch64InstrInfo.td

def HasTRACEV8_4         : Predicate<"Subtarget->hasTRACEV8_4()">,
                        AssemblerPredicate<"FeatureTRACEV8_4", "tracev8.4">;
 
 def HasAM            : Predicate<"Subtarget->hasAM()">,
                        AssemblerPredicate<"FeatureAM", "am">;
 
 def HasSEL2          : Predicate<"Subtarget->hasSEL2()">,
                        AssemblerPredicate<"FeatureSEL2", "sel2">;
 
+def HasPMU           : Predicate<"Subtarget->hasPMU()">,
+                       AssemblerPredicate<"FeaturePMU", "pmu">;
+
 def HasTLB_RMI          : Predicate<"Subtarget->hasTLB_RMI()">,
                        AssemblerPredicate<"FeatureTLB_RMI", "tlb-rmi">;
 
 def HasFMI           : Predicate<"Subtarget->hasFMI()">,
                        AssemblerPredicate<"FeatureFMI", "fmi">;
 
 def HasRCPC_IMMO      : Predicate<"Subtarget->hasRCPCImm()">,
                        AssemblerPredicate<"FeatureRCPC_IMMO", "rcpc-immo">;

llvm/lib/Target/AArch64/AArch64Subtarget.h

protected:
   // ARMv8.4 extensions
   bool HasNV = false;
   bool HasRASv8_4 = false;
   bool HasMPAM = false;
   bool HasDIT = false;
   bool HasTRACEV8_4 = false;
   bool HasAM = false;
   bool HasSEL2 = false;
+  bool HasPMU = false;
   bool HasTLB_RMI = false;
   bool HasFMI = false;
   bool HasRCPC_IMMO = false;
 
   bool HasLSLFast = false;
   bool HasSVE = false;
   bool HasSVE2 = false;
   bool HasRCPC = false;
public:
 
   bool hasNV() const { return HasNV; }
   bool hasRASv8_4() const { return HasRASv8_4; }
   bool hasMPAM() const { return HasMPAM; }
   bool hasDIT() const { return HasDIT; }
   bool hasTRACEV8_4() const { return HasTRACEV8_4; }
   bool hasAM() const { return HasAM; }
   bool hasSEL2() const { return HasSEL2; }
+  bool hasPMU() const { return HasPMU; }
   bool hasTLB_RMI() const { return HasTLB_RMI; }
   bool hasFMI() const { return HasFMI; }
   bool hasRCPC_IMMO() const { return HasRCPC_IMMO; }
 
   bool addrSinkUsingGEPs() const override {
     // Keeping GEPs inbounds is important for exploiting AArch64
     // addressing-modes in ILP32 mode.
     return useAA() || isTargetILP32();

llvm/lib/Target/AArch64/AArch64SystemOperands.td

 def : RWSysReg<"CNTHPS_CVAL_EL2", 0b11, 0b100, 0b1110, 0b0101, 0b010>;
 def : RWSysReg<"CNTHPS_CTL_EL2",  0b11, 0b100, 0b1110, 0b0101, 0b001>;
 
 // v8.4a "Virtualization debug state" registers
 //                           Op0   Op1    CRn     CRm     Op2
 def : RWSysReg<"SDER32_EL2", 0b11, 0b100, 0b0001, 0b0011, 0b001>;
 } // FeatureSEL2
 
+// v8.4a PMU registers
+//                          Op0   Op1    CRn     CRm     Op2
+let Requires = [{ {AArch64::FeaturePMU} }] in {
+def : RWSysReg<"PMMIR_EL1", 0b11, 0b000, 0b1001, 0b1110, 0b110>;
+} // FeaturePMU
+
 // v8.4a RAS registers
 //                              Op0   Op1    CRn     CRm     Op2
 let Requires = [{ {AArch64::FeatureRASv8_4} }] in {
 def : RWSysReg<"ERXPFGCTL_EL1", 0b11, 0b000, 0b0101, 0b0100, 0b101>;
 def : RWSysReg<"ERXPFGCDN_EL1", 0b11, 0b000, 0b0101, 0b0100, 0b110>;
 def : RWSysReg<"ERXTS_EL1",     0b11, 0b000, 0b0101, 0b0101, 0b111>;
 def : RWSysReg<"ERXMISC2_EL1",  0b11, 0b000, 0b0101, 0b0101, 0b010>;
 def : RWSysReg<"ERXMISC3_EL1",  0b11, 0b000, 0b0101, 0b0101, 0b011>;

llvm/test/MC/AArch64/armv8.4a-pmu.s

+// RUN: llvm-mc -triple aarch64-none-linux-gnu -show-encoding -mattr=+v8.4a < %s \
+// RUN: | FileCheck %s --check-prefix=CHECK
+
+// RUN: not llvm-mc -triple aarch64-none-linux-gnu -show-encoding -mattr=-v8.4a < %s 2>&1 \
+// RUN: | FileCheck %s --check-prefix=CHECK-ERROR
+
+//------------------------------------------------------------------------------
+// ARMV8.4-A PMU
+//------------------------------------------------------------------------------
+
+// Read/Write registers:
+
+msr PMMIR_EL1, x0
+mrs x0, PMMIR_EL1
+
+//CHECK: msr     PMMIR_EL1, x0           // encoding: [0xc0,0x9e,0x18,0xd5]
+//CHECK: mrs     x0, PMMIR_EL1           // encoding: [0xc0,0x9e,0x38,0xd5]
+//CHECK-ERROR: error: expected writable system register or pstate
+//CHECK-ERROR: error: expected readable system register

llvm/test/MC/Disassembler/AArch64/armv8.4a-pmu.txt

+#RUN: llvm-mc -triple aarch64-none-linux-gnu -mattr=+v8.4a --disassemble < %s | FileCheck %s
+#RUN: llvm-mc -triple aarch64-none-linux-gnu -mattr=-v8.4a --disassemble < %s | FileCheck %s --check-prefix=CHECK-NOV84
+
+[0xc0,0x9e,0x18,0xd5]
+[0xc0,0x9e,0x38,0xd5]
+
+#CHECK:  msr PMMIR_EL1, x0
+#CHECK:  mrs x0, PMMIR_EL1
+#CHECK-NOV84:  msr S3_0_C9_C14_6, x0
+#CHECK-NOV84:  mrs x0, S3_0_C9_C14_6