[clang] [llvm] [RISCV][VLS] Support RISCV VLS calling convention (PR #100346)

[Kito Cheng via llvm-commits]

================
@@ -5220,6 +5248,30 @@ bool Sema::CheckCallingConvAttr(const ParsedAttr &Attrs, CallingConv &CC,
   case ParsedAttr::AT_RISCVVectorCC:
     CC = CC_RISCVVectorCall;
     break;
+  case ParsedAttr::AT_RISCVVLSCC: {
+    // If the riscv_abi_vlen doesn't have any argument, we set set it to default
+    // value 128.
+    unsigned ABIVLen = 128;
+    if (Attrs.getNumArgs() &&
+        !checkUInt32Argument(Attrs, Attrs.getArgAsExpr(0), ABIVLen)) {
+    Attrs.setInvalid();
+      return true;
+    }
+    if (Attrs.getNumArgs() && (ABIVLen < 32 || ABIVLen > 65536)) {
+    Attrs.setInvalid();
+      Diag(Attrs.getLoc(), diag::err_argument_invalid_range)
+          << ABIVLen << 32 << 65536;
+      return true;
----------------
kito-cheng wrote:

```suggestion
    if (Attrs.getNumArgs() && (ABIVLen < 32 || ABIVLen > 65536)) {
      Attrs.setInvalid();
      Diag(Attrs.getLoc(), diag::err_argument_invalid_range)
          << ABIVLen << 32 << 65536;
      return true;
```

https://github.com/llvm/llvm-project/pull/100346