[AArch64] Add support for the Branch Record Buffer extension

[pratlucas]

Summary

This introduces asm support for the Branch Record Buffer extension, through
the new 'brbe' subtarget feature. It consists of a new set of system registers
that enable the handling of branch records.

Patch written by Simon Tatham.

[pratlucas]

Ping.

[pratlucas]

Rebasing.

[ostannard]

LGTM

llvm/include/llvm/Support/AArch64TargetParser.h

enum ArchExtKind : uint64_t {
   AEK_SVE2SHA3 =    1 << 26,
   AEK_SVE2BITPERM = 1 << 27,
   AEK_TME =         1 << 28,
   AEK_BF16 =        1 << 29,
   AEK_I8MM =        1 << 30,
   AEK_F32MM =       1ULL << 31,
   AEK_F64MM =       1ULL << 32,
   AEK_LS64 =        1ULL << 33,
+  AEK_BRBE =        1ULL << 34,
 };
 
 enum class ArchKind {
 #define AARCH64_ARCH(NAME, ID, CPU_ATTR, SUB_ARCH, ARCH_ATTR, ARCH_FPU, ARCH_BASE_EXT) ID,
 #include "AArch64TargetParser.def"
 };
 
 const ARM::ArchNames<ArchKind> AArch64ARCHNames[] = {

llvm/include/llvm/Support/AArch64TargetParser.def

 AARCH64_ARCH_EXT_NAME("sb",           AArch64::AEK_SB,          "+sb",    "-sb")
 AARCH64_ARCH_EXT_NAME("predres",      AArch64::AEK_PREDRES,     "+predres", "-predres")
 AARCH64_ARCH_EXT_NAME("bf16",         AArch64::AEK_BF16,        "+bf16",  "-bf16")
 AARCH64_ARCH_EXT_NAME("i8mm",         AArch64::AEK_I8MM,        "+i8mm",  "-i8mm")
 AARCH64_ARCH_EXT_NAME("f32mm",        AArch64::AEK_F32MM,       "+f32mm", "-f32mm")
 AARCH64_ARCH_EXT_NAME("f64mm",        AArch64::AEK_F64MM,       "+f64mm", "-f64mm")
 AARCH64_ARCH_EXT_NAME("tme",          AArch64::AEK_TME,         "+tme",   "-tme")
 AARCH64_ARCH_EXT_NAME("ls64",         AArch64::AEK_LS64,        "+ls64",  "-ls64")
+AARCH64_ARCH_EXT_NAME("brbe",         AArch64::AEK_BRBE,        "+brbe",  "-brbe")
 #undef AARCH64_ARCH_EXT_NAME
 
 #ifndef AARCH64_CPU_NAME
 #define AARCH64_CPU_NAME(NAME, ID, DEFAULT_FPU, IS_DEFAULT, DEFAULT_EXT)
 #endif
 AARCH64_CPU_NAME("cortex-a34", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false,
                  (AArch64::AEK_CRC))
 AARCH64_CPU_NAME("cortex-a35", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false,

llvm/lib/Support/AArch64TargetParser.cpp

bool AArch64::getExtensionFeatures(uint64_t Extensions,
   if (Extensions & AEK_SVE2SM4)
     Features.push_back("+sve2-sm4");
   if (Extensions & AEK_SVE2SHA3)
     Features.push_back("+sve2-sha3");
   if (Extensions & AEK_SVE2BITPERM)
     Features.push_back("+sve2-bitperm");
   if (Extensions & AEK_RCPC)
     Features.push_back("+rcpc");
+  if (Extensions & AEK_BRBE)
+    Features.push_back("+brbe");
 
   return true;
 }
 
 bool AArch64::getArchFeatures(AArch64::ArchKind AK,
                               std::vector<StringRef> &Features) {
   if (AK == ArchKind::ARMV8_1A)
     Features.push_back("+v8.1a");

llvm/lib/Target/AArch64/AArch64.td

def FeatureWFxT : SubtargetFeature<"wfxt", "HasWFxT",
     "true", "Enable Armv8.7-A WFET and WFIT instruction">;
 
 def FeatureHCX : SubtargetFeature<
     "hcx", "HasHCX", "true", "Enable Armv8.7-A HCRX_EL2 system register">;
 
 def FeatureLS64 : SubtargetFeature<"ls64", "HasLS64",
     "true", "Enable Armv8.7-A LD64B/ST64B Accelerator Extension">;
 
+def FeatureBRBE : SubtargetFeature<"brbe", "HasBRBE",
+    "true", "Enable Branch Record Buffer Extension">;
+
 def FeatureFineGrainedTraps : SubtargetFeature<"fgt", "HasFineGrainedTraps",
     "true", "Enable fine grained virtualization traps extension">;
 
 def FeatureEnhancedCounterVirtualization :
       SubtargetFeature<"ecv", "HasEnhancedCounterVirtualization",
       "true", "Enable enhanced counter virtualization extension">;
 
 //===----------------------------------------------------------------------===//

llvm/lib/Target/AArch64/AArch64InstrInfo.td

 def HasMatMulFP64    : Predicate<"Subtarget->hasMatMulFP64()">,
                        AssemblerPredicate<(all_of FeatureMatMulFP64), "f64mm">;
 def HasXS            : Predicate<"Subtarget->hasXS()">,
                        AssemblerPredicate<(all_of FeatureXS), "xs">;
 def HasWFxT          : Predicate<"Subtarget->hasWFxT()">,
                        AssemblerPredicate<(all_of FeatureWFxT), "wfxt">;
 def HasLS64          : Predicate<"Subtarget->hasLS64()">,
                        AssemblerPredicate<(all_of FeatureLS64), "ls64">;
+def HasBRBE          : Predicate<"Subtarget->hasBRBE()">,
+                       AssemblerPredicate<(all_of FeatureBRBE), "brbe">;
 def IsLE             : Predicate<"Subtarget->isLittleEndian()">;
 def IsBE             : Predicate<"!Subtarget->isLittleEndian()">;
 def IsWindows        : Predicate<"Subtarget->isTargetWindows()">;
 def UseExperimentalZeroingPseudos
     : Predicate<"Subtarget->useExperimentalZeroingPseudos()">;
 def UseAlternateSExtLoadCVTF32
     : Predicate<"Subtarget->useAlternateSExtLoadCVTF32Pattern()">;
 

llvm/lib/Target/AArch64/AArch64Subtarget.h

protected:
   bool HasSVE2AES = false;
   bool HasSVE2SM4 = false;
   bool HasSVE2SHA3 = false;
   bool HasSVE2BitPerm = false;
 
   // Future architecture extensions.
   bool HasETE = false;
   bool HasTRBE = false;
+  bool HasBRBE = false;
 
   // HasZeroCycleRegMove - Has zero-cycle register mov instructions.
   bool HasZeroCycleRegMove = false;
 
   // HasZeroCycleZeroing - Has zero-cycle zeroing instructions.
   bool HasZeroCycleZeroing = false;
   bool HasZeroCycleZeroingGP = false;
   bool HasZeroCycleZeroingFP = false;

llvm/lib/Target/AArch64/AArch64SystemOperands.td

 def : RWSysReg<"CNTPCTSS_EL0",     0b11, 0b011, 0b1110, 0b0000, 0b101>;
 def : RWSysReg<"CNTVCTSS_EL0",     0b11, 0b011, 0b1110, 0b0000, 0b110>;
 }
 
 // v8.7a LD64B/ST64B Accelerator Extension system register
 let Requires = [{ {AArch64::FeatureLS64} }] in
 def : RWSysReg<"ACCDATA_EL1",       0b11, 0b000, 0b1101, 0b0000, 0b101>;
 
+// Branch Record Buffer system registers
+let Requires = [{ {AArch64::FeatureBRBE} }] in {
+def : RWSysReg<"BRBCR_EL1",         0b10, 0b001, 0b1001, 0b0000, 0b000>;
+def : RWSysReg<"BRBCR_EL12",        0b10, 0b101, 0b1001, 0b0000, 0b000>;
+def : RWSysReg<"BRBCR_EL2",         0b10, 0b100, 0b1001, 0b0000, 0b000>;
+def : RWSysReg<"BRBFCR_EL1",        0b10, 0b001, 0b1001, 0b0000, 0b001>;
+def : ROSysReg<"BRBIDR0_EL1",       0b10, 0b001, 0b1001, 0b0010, 0b000>;
+def : RWSysReg<"BRBINFINJ_EL1",     0b10, 0b001, 0b1001, 0b0001, 0b000>;
+def : RWSysReg<"BRBSRCINJ_EL1",     0b10, 0b001, 0b1001, 0b0001, 0b001>;
+def : RWSysReg<"BRBTGTINJ_EL1",     0b10, 0b001, 0b1001, 0b0001, 0b010>;
+def : RWSysReg<"BRBTS_EL1",         0b10, 0b001, 0b1001, 0b0000, 0b010>;
+foreach n = 0-31 in {
+  defvar nb = !cast<bits<5>>(n);
+  def : ROSysReg<"BRBINF"#n#"_EL1", 0b10, 0b001, 0b1000, nb{3-0}, {nb{4},0b00}>;
+  def : ROSysReg<"BRBSRC"#n#"_EL1", 0b10, 0b001, 0b1000, nb{3-0}, {nb{4},0b01}>;
+  def : ROSysReg<"BRBTGT"#n#"_EL1", 0b10, 0b001, 0b1000, nb{3-0}, {nb{4},0b10}>;
+}
+}
+
 // Cyclone specific system registers
 //                                 Op0    Op1     CRn     CRm    Op2
 let Requires = [{ {AArch64::ProcAppleA7} }] in
 def : RWSysReg<"CPM_IOACC_CTL_EL3", 0b11, 0b111, 0b1111, 0b0010, 0b000>;

llvm/test/MC/AArch64/brbe.s

+// RUN: not llvm-mc -triple aarch64 -mattr +brbe -show-encoding %s 2>%t | FileCheck %s
+// RUN: FileCheck --check-prefix=ERROR %s < %t
+// RUN: not llvm-mc -triple aarch64 -show-encoding %s 2>%t
+// RUN: FileCheck --check-prefix=ERROR-NO-BRBE %s < %t
+
+msr BRBCR_EL1, x0
+mrs x1, BRBCR_EL1
+// CHECK: msr     BRBCR_EL1, x0           // encoding: [0x00,0x90,0x11,0xd5]
+// CHECK: mrs     x1, BRBCR_EL1           // encoding: [0x01,0x90,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBCR_EL12, x2
+mrs x3, BRBCR_EL12
+// CHECK: msr     BRBCR_EL12, x2          // encoding: [0x02,0x90,0x15,0xd5]
+// CHECK: mrs     x3, BRBCR_EL12          // encoding: [0x03,0x90,0x35,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBCR_EL2, x4
+mrs x5, BRBCR_EL2
+// CHECK: msr     BRBCR_EL2, x4           // encoding: [0x04,0x90,0x14,0xd5]
+// CHECK: mrs     x5, BRBCR_EL2           // encoding: [0x05,0x90,0x34,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBFCR_EL1, x6
+mrs x7, BRBFCR_EL1
+// CHECK: msr     BRBFCR_EL1, x6          // encoding: [0x26,0x90,0x11,0xd5]
+// CHECK: mrs     x7, BRBFCR_EL1          // encoding: [0x27,0x90,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBIDR0_EL1, x8
+mrs x9, BRBIDR0_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x9, BRBIDR0_EL1         // encoding: [0x09,0x92,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBINFINJ_EL1, x10
+mrs x11, BRBINFINJ_EL1
+// CHECK: msr     BRBINFINJ_EL1, x10      // encoding: [0x0a,0x91,0x11,0xd5]
+// CHECK: mrs     x11, BRBINFINJ_EL1      // encoding: [0x0b,0x91,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBSRCINJ_EL1, x12
+mrs x13, BRBSRCINJ_EL1
+// CHECK: msr     BRBSRCINJ_EL1, x12      // encoding: [0x2c,0x91,0x11,0xd5]
+// CHECK: mrs     x13, BRBSRCINJ_EL1      // encoding: [0x2d,0x91,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBTGTINJ_EL1, x14
+mrs x15, BRBTGTINJ_EL1
+// CHECK: msr     BRBTGTINJ_EL1, x14      // encoding: [0x4e,0x91,0x11,0xd5]
+// CHECK: mrs     x15, BRBTGTINJ_EL1      // encoding: [0x4f,0x91,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBTS_EL1, x16
+mrs x17, BRBTS_EL1
+// CHECK: msr     BRBTS_EL1, x16          // encoding: [0x50,0x90,0x11,0xd5]
+// CHECK: mrs     x17, BRBTS_EL1          // encoding: [0x51,0x90,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+// Rather than testing all 32 registers in the three BRBINF/BRBSRC/BRBTGT
+// families, I'll test a representative sample, including all bits clear,
+// all bits set, each bit set individually, and a couple of intermediate
+// patterns.
+
+msr BRBINF0_EL1, x18
+mrs x19, BRBINF0_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x19, BRBINF0_EL1        // encoding: [0x13,0x80,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBINF1_EL1, x20
+mrs x21, BRBINF1_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x21, BRBINF1_EL1        // encoding: [0x15,0x81,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBINF2_EL1, x22
+mrs x23, BRBINF2_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x23, BRBINF2_EL1        // encoding: [0x17,0x82,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBSRC4_EL1, x24
+mrs x25, BRBSRC4_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x25, BRBSRC4_EL1        // encoding: [0x39,0x84,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBSRC8_EL1, x26
+mrs x27, BRBSRC8_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x27, BRBSRC8_EL1        // encoding: [0x3b,0x88,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBSRC16_EL1, x28
+mrs x29, BRBSRC16_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x29, BRBSRC16_EL1       // encoding: [0xbd,0x80,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:10: error: expected readable system register
+
+msr BRBTGT10_EL1, x0
+mrs x1, BRBTGT10_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x1, BRBTGT10_EL1        // encoding: [0x41,0x8a,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBTGT21_EL1, x2
+mrs x3, BRBTGT21_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x3, BRBTGT21_EL1        // encoding: [0xc3,0x85,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register
+
+msr BRBTGT31_EL1, x4
+mrs x5, BRBTGT31_EL1
+// ERROR: [[@LINE-2]]:5: error: expected writable system register
+// CHECK: mrs     x5, BRBTGT31_EL1        // encoding: [0xc5,0x8f,0x31,0xd5]
+// ERROR-NO-BRBE: [[@LINE-4]]:5: error: expected writable system register
+// ERROR-NO-BRBE: [[@LINE-4]]:9: error: expected readable system register

llvm/test/MC/Disassembler/AArch64/brbe.txt

+# RUN: llvm-mc -triple=aarch64 -mattr=+brbe -disassemble %s 2> %t | FileCheck %s
+# RUN: llvm-mc -triple=aarch64 -disassemble %s 2> %t | FileCheck --check-prefix=NO-BRBE %s
+
+[0x00,0x90,0x11,0xd5]
+[0x01,0x90,0x31,0xd5]
+# CHECK:   msr     BRBCR_EL1, x0
+# CHECK:   mrs     x1, BRBCR_EL1
+# NO-BRBE: msr     S2_1_C9_C0_0, x0
+# NO-BRBE: mrs     x1, S2_1_C9_C0_0
+
+[0x02,0x90,0x15,0xd5]
+[0x03,0x90,0x35,0xd5]
+# CHECK:   msr     BRBCR_EL12, x2
+# CHECK:   mrs     x3, BRBCR_EL12
+# NO-BRBE: msr     S2_5_C9_C0_0, x2
+# NO-BRBE: mrs     x3, S2_5_C9_C0_0
+
+[0x04,0x90,0x14,0xd5]
+[0x05,0x90,0x34,0xd5]
+# CHECK:   msr     BRBCR_EL2, x4
+# CHECK:   mrs     x5, BRBCR_EL2
+# NO-BRBE: msr     S2_4_C9_C0_0, x4
+# NO-BRBE: mrs     x5, S2_4_C9_C0_0
+
+[0x26,0x90,0x11,0xd5]
+[0x27,0x90,0x31,0xd5]
+# CHECK:   msr     BRBFCR_EL1, x6
+# CHECK:   mrs     x7, BRBFCR_EL1
+# NO-BRBE: msr     S2_1_C9_C0_1, x6
+# NO-BRBE: mrs     x7, S2_1_C9_C0_1
+
+[0x08,0x92,0x11,0xd5] # expect failure: BRBIDR0_EL1 is RO
+[0x09,0x92,0x31,0xd5]
+# CHECK:   msr     S2_1_C9_C2_0, x8
+# CHECK:   mrs     x9, BRBIDR0_EL1
+# NO-BRBE: msr     S2_1_C9_C2_0, x8
+# NO-BRBE: mrs     x9, S2_1_C9_C2_0
+
+[0x0a,0x91,0x11,0xd5]
+[0x0b,0x91,0x31,0xd5]
+# CHECK:   msr     BRBINFINJ_EL1, x10
+# CHECK:   mrs     x11, BRBINFINJ_EL1
+# NO-BRBE: msr     S2_1_C9_C1_0, x10
+# NO-BRBE: mrs     x11, S2_1_C9_C1_0
+
+[0x2c,0x91,0x11,0xd5]
+[0x2d,0x91,0x31,0xd5]
+# CHECK:   msr     BRBSRCINJ_EL1, x12
+# CHECK:   mrs     x13, BRBSRCINJ_EL1
+# NO-BRBE: msr     S2_1_C9_C1_1, x12
+# NO-BRBE: mrs     x13, S2_1_C9_C1_1
+
+[0x4e,0x91,0x11,0xd5]
+[0x4f,0x91,0x31,0xd5]
+# CHECK:   msr     BRBTGTINJ_EL1, x14
+# CHECK:   mrs     x15, BRBTGTINJ_EL1
+# NO-BRBE: msr     S2_1_C9_C1_2, x14
+# NO-BRBE: mrs     x15, S2_1_C9_C1_2
+
+[0x50,0x90,0x11,0xd5]
+[0x51,0x90,0x31,0xd5]
+# CHECK:   msr     BRBTS_EL1, x16
+# CHECK:   mrs     x17, BRBTS_EL1
+# NO-BRBE: msr     S2_1_C9_C0_2, x16
+# NO-BRBE: mrs     x17, S2_1_C9_C0_2
+
+[0x12,0x80,0x11,0xd5] # expect failure: BRBINF0_EL1 is RO
+[0x13,0x80,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C0_0, x18
+# CHECK:   mrs     x19, BRBINF0_EL1
+# NO-BRBE: msr     S2_1_C8_C0_0, x18
+# NO-BRBE: mrs     x19, S2_1_C8_C0_0
+
+[0x14,0x81,0x11,0xd5] # expect failure: BRBINF1_EL1 is RO
+[0x15,0x81,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C1_0, x20
+# CHECK:   mrs     x21, BRBINF1_EL1
+# NO-BRBE: msr     S2_1_C8_C1_0, x20
+# NO-BRBE: mrs     x21, S2_1_C8_C1_0
+
+[0x16,0x82,0x11,0xd5] # expect failure: BRBINF2_EL1 is RO
+[0x17,0x82,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C2_0, x22
+# CHECK:   mrs     x23, BRBINF2_EL1
+# NO-BRBE: msr     S2_1_C8_C2_0, x22
+# NO-BRBE: mrs     x23, S2_1_C8_C2_0
+
+[0x38,0x84,0x11,0xd5] # expect failure: BRBSRC4_EL1 is RO
+[0x39,0x84,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C4_1, x24
+# CHECK:   mrs     x25, BRBSRC4_EL1
+# NO-BRBE: msr     S2_1_C8_C4_1, x24
+# NO-BRBE: mrs     x25, S2_1_C8_C4_1
+
+[0x3a,0x88,0x11,0xd5] # expect failure: BRBSRC8_EL1 is RO
+[0x3b,0x88,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C8_1, x26
+# CHECK:   mrs     x27, BRBSRC8_EL1
+# NO-BRBE: msr     S2_1_C8_C8_1, x26
+# NO-BRBE: mrs     x27, S2_1_C8_C8_1
+
+[0xbc,0x80,0x11,0xd5] # expect failure: BRBSRC16_EL1 is RO
+[0xbd,0x80,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C0_5, x28
+# CHECK:   mrs     x29, BRBSRC16_EL1
+# NO-BRBE: msr     S2_1_C8_C0_5, x28
+# NO-BRBE: mrs     x29, S2_1_C8_C0_5
+
+[0x40,0x8a,0x11,0xd5] # expect failure: BRBTGT10_EL1 is RO
+[0x41,0x8a,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C10_2, x0
+# CHECK:   mrs     x1, BRBTGT10_EL1
+# NO-BRBE: msr     S2_1_C8_C10_2, x0
+# NO-BRBE: mrs     x1, S2_1_C8_C10_2
+
+[0xc2,0x85,0x11,0xd5] # expect failure: BRBTGT21_EL1 is RO
+[0xc3,0x85,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C5_6, x2
+# CHECK:   mrs     x3, BRBTGT21_EL1
+# NO-BRBE: msr     S2_1_C8_C5_6, x2
+# NO-BRBE: mrs     x3, S2_1_C8_C5_6
+
+[0xc4,0x8f,0x11,0xd5] # expect failure: BRBTGT31_EL1 is RO
+[0xc5,0x8f,0x31,0xd5]
+# CHECK:   msr     S2_1_C8_C15_6, x4
+# CHECK:   mrs     x5, BRBTGT31_EL1
+# NO-BRBE: msr     S2_1_C8_C15_6, x4
+# NO-BRBE: mrs     x5, S2_1_C8_C15_6