[ARM][AArch64] Enable FEAT_FHM for Arm Neoverse N2 (llvm#82613)

Correct an issue with Arm Neoverse N2 after it was
changed to a v9a core in change
f576cbe:

  * FEAT_FHM should be enabled for this core.

Author: jthackray

llvm/include/llvm/TargetParser/AArch64TargetParser.h

@@ -658,8 +658,8 @@ inline constexpr CpuInfo CpuInfos[] = {
           AArch64::AEK_SSBS}))},
     {"neoverse-n2", ARMV9A,
      (AArch64::ExtensionBitset(
-         {AArch64::AEK_BF16, AArch64::AEK_DOTPROD,
-          AArch64::AEK_FP16, AArch64::AEK_I8MM, AArch64::AEK_MTE,
+         {AArch64::AEK_BF16, AArch64::AEK_DOTPROD, AArch64::AEK_FP16,
+          AArch64::AEK_FP16FML, AArch64::AEK_I8MM, AArch64::AEK_MTE,
           AArch64::AEK_SB, AArch64::AEK_SSBS, AArch64::AEK_SVE,
           AArch64::AEK_SVE2, AArch64::AEK_SVE2BITPERM}))},
     {"neoverse-512tvb", ARMV8_4A,

llvm/include/llvm/TargetParser/ARMTargetParser.def

@@ -346,8 +346,8 @@ ARM_CPU_NAME("cortex-x1c", ARMV8_2A, FK_CRYPTO_NEON_FP_ARMV8, false,
 ARM_CPU_NAME("neoverse-n1", ARMV8_2A, FK_CRYPTO_NEON_FP_ARMV8, false,
              (ARM::AEK_FP16 | ARM::AEK_DOTPROD))
 ARM_CPU_NAME("neoverse-n2", ARMV9A, FK_NEON_FP_ARMV8, false,
-             (ARM::AEK_BF16 | ARM::AEK_DOTPROD | ARM::AEK_I8MM | ARM::AEK_RAS |
-              ARM::AEK_SB))
+             (ARM::AEK_BF16 | ARM::AEK_DOTPROD | ARM::AEK_FP16FML |
+              ARM::AEK_I8MM | ARM::AEK_RAS | ARM::AEK_SB ))
 ARM_CPU_NAME("neoverse-v1", ARMV8_4A, FK_CRYPTO_NEON_FP_ARMV8, false,
              (ARM::AEK_RAS | ARM::AEK_FP16 | ARM::AEK_BF16 | ARM::AEK_DOTPROD))
 ARM_CPU_NAME("cyclone", ARMV8A, FK_CRYPTO_NEON_FP_ARMV8, false, ARM::AEK_CRC)

llvm/lib/Target/AArch64/AArch64.td

@@ -1514,7 +1514,7 @@ def ProcessorFeatures {
                                        FeatureFPARMv8, FeatureFullFP16, FeatureNEON,
                                        FeatureRCPC, FeatureSPE, FeatureSSBS,
                                        FeaturePerfMon];
-  list<SubtargetFeature> NeoverseN2 = [HasV9_0aOps, FeatureBF16, FeatureETE,
+  list<SubtargetFeature> NeoverseN2 = [HasV9_0aOps, FeatureBF16, FeatureETE, FeatureFP16FML,
                                        FeatureMatMulInt8, FeatureMTE, FeatureSVE2,
                                        FeatureSVE2BitPerm, FeatureTRBE,
                                        FeaturePerfMon];

llvm/lib/Target/ARM/ARM.td

@@ -1682,6 +1682,7 @@ def : ProcNoItin<"neoverse-n1",                         [ARMv82a,
 
 def : ProcNoItin<"neoverse-n2",                         [ARMv9a,
                                                          FeatureBF16,
+                                                         FeatureFP16FML,
                                                          FeatureMatMulInt8]>;
 
 def : ProcessorModel<"cyclone",     SwiftModel,         [ARMv8a, ProcSwift,

llvm/unittests/TargetParser/TargetParserTest.cpp

@@ -439,7 +439,7 @@ INSTANTIATE_TEST_SUITE_P(
                              ARM::AEK_HWDIVARM | ARM::AEK_MP | ARM::AEK_SEC |
                              ARM::AEK_VIRT | ARM::AEK_DSP | ARM::AEK_BF16 |
                              ARM::AEK_DOTPROD | ARM::AEK_RAS | ARM::AEK_I8MM |
-                             ARM::AEK_SB,
+                             ARM::AEK_FP16FML | ARM::AEK_SB,
             "9-A"),
         ARMCPUTestParams<uint64_t>("neoverse-v1", "armv8.4-a", "crypto-neon-fp-armv8",
             ARM::AEK_SEC | ARM::AEK_MP | ARM::AEK_VIRT |
@@ -1575,8 +1575,9 @@ INSTANTIATE_TEST_SUITE_P(
                  AArch64::AEK_SB,          AArch64::AEK_SVE2,
                  AArch64::AEK_SVE2BITPERM, AArch64::AEK_BF16,
                  AArch64::AEK_I8MM,        AArch64::AEK_JSCVT,
-                 AArch64::AEK_FCMA,        AArch64::AEK_PAUTH})),
-            "8.5-A"),
+                 AArch64::AEK_FCMA,        AArch64::AEK_PAUTH,
+                 AArch64::AEK_FP16FML})),
+            "9-A"),
         ARMCPUTestParams<AArch64::ExtensionBitset>(
             "ampere1", "armv8.6-a", "crypto-neon-fp-armv8",
             (AArch64::ExtensionBitset(