[clang] [llvm] [RISCV][MC] Introduce XSfvfexp* and XSfvfbfexpa* extensions and their MC supports (PR #164349)

[Min-Yih Hsu via cfe-commits]

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@@ -1334,6 +1334,44 @@ def HasVendorXSfvfnrclipxfqf
       AssemblerPredicate<(all_of FeatureVendorXSfvfnrclipxfqf),
                          "'XSfvfnrclipxfqf' (SiFive FP32-to-int8 Ranged Clip Instructions)">;
 
+// Note: XSfvfbfexp16e depends on either Zvfbfmin _or_ Zvfbfa, which cannot be expressed here in
+// TableGen. Instead, we check that in RISCVISAInfo.
+def FeatureVendorXSfvfbfexp16e
+    : RISCVExtension<0, 5,
+                     "SiFive Vector Floating-Point Exponential Function Instruction, BFloat16">;
+def HasVendorXSfvfbfexp16e : Predicate<"Subtarget->hasVendorXSfvfbfexp16e()">;
+
+def FeatureVendorXSfvfexp16e
+    : RISCVExtension<0, 5,
+                     "SiFive Vector Floating-Point Exponential Function Instruction, Half Precision",
+                     [FeatureStdExtZvfh]>;
+def HasVendorXSfvfexp16e : Predicate<"Subtarget->hasVendorXSfvfexp16e()">;
+
+def FeatureVendorXSfvfexp32e
+    : RISCVExtension<0, 5,
+                     "SiFive Vector Floating-Point Exponential Function Instruction, Single Precision",
+                     [FeatureStdExtZve32f]>;
+def HasVendorXSfvfexp32e : Predicate<"Subtarget->hasVendorXSfvfexp32e()">;
+
+def HasVendorXSfvfexpAnyFloat : Predicate<"Subtarget->hasVendorXSfvfexp16e() || Subtarget->hasVendorXSfvfexp32e()">;
+def HasVendorXSfvfexpAny : Predicate<"Subtarget->hasVendorXSfvfbfexp16e() || Subtarget->hasVendorXSfvfexp16e() || Subtarget->hasVendorXSfvfexp32e()">,
+                           AssemblerPredicate<(any_of FeatureVendorXSfvfbfexp16e, FeatureVendorXSfvfexp16e, FeatureVendorXSfvfexp32e),
+                           "'Xsfvfbfexp16e/Xsfvfexp16e/Xsfvfexp32e' (SiFive Vector Floating-Point Exponential Function Instruction)">;
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mshockwave wrote:

`HasVInstructionAnyF` uses comma:
```
          "'V' (Vector Extension for Application Processors), 'Zve32f' "
          "(Vector Extensions for Embedded Processors)"
```
do you think we should use comma here as well? Like "'Xsfvfbfexp16e', 'Xsfvfexp16e', or 'Xsfvfexp32e' (SiFive Vector Floating-Point Exponential Function Instruction)"

https://github.com/llvm/llvm-project/pull/164349