[Clang][RISCV] Guard vector float16 type correctly with semantic anal…

…ysis

Before this commit, vector float 16 types (e.g. `vfloat16m1_t`) of RVV
is only defined when extension `zvfh` is defined. However this
generate inaccurate diagnostics like:

```
error: unknown type name 'vfloat16m1_t'
```

This commit improves the compiler by guarding type check correctly
under semantic analysis.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D143657

clang/include/clang/AST/Type.h

@@ -2275,6 +2275,8 @@ class alignas(8) Type : public ExtQualsTypeCommonBase {
 
   bool isRVVType() const;
 
+  bool isRVVType(unsigned Bitwidth, bool IsFloat) const;
+
   /// Return the implicit lifetime for this type, which must not be dependent.
   Qualifiers::ObjCLifetime getObjCARCImplicitLifetime() const;
 
@@ -7153,6 +7155,17 @@ inline bool Type::isRVVType() const {
     false; // end of boolean or operation.
 }
 
+inline bool Type::isRVVType(unsigned Bitwidth, bool IsFloat) const {
+  bool Ret = false;
+#define RVV_TYPE(Name, Id, SingletonId)
+#define RVV_VECTOR_TYPE(Name, Id, SingletonId, NumEls, ElBits, NF, IsSigned,   \
+                        IsFP)                                                  \
+  if (ElBits == Bitwidth && IsFloat == IsFP)                                   \
+    Ret |= isSpecificBuiltinType(BuiltinType::Id);
+#include "clang/Basic/RISCVVTypes.def"
+  return Ret;
+}
+
 inline bool Type::isTemplateTypeParmType() const {
   return isa<TemplateTypeParmType>(CanonicalType);
 }

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -11738,6 +11738,9 @@ def err_riscv_builtin_requires_extension : Error<
   "builtin requires%select{| at least one of the following extensions to be enabled}0: %1">;
 def err_riscv_builtin_invalid_lmul : Error<
   "LMUL argument must be in the range [0,3] or [5,7]">;
+def err_riscv_type_requires_extension : Error<
+  "RISC-V type %0 requires the '%1' extension"
+>;
 
 def err_std_source_location_impl_not_found : Error<
   "'std::source_location::__impl' was not found; it must be defined before '__builtin_source_location' is called">;

clang/lib/Sema/Sema.cpp

@@ -2039,6 +2039,12 @@ void Sema::checkTypeSupport(QualType Ty, SourceLocation Loc, ValueDecl *D) {
         targetDiag(D->getLocation(), diag::note_defined_here, FD) << D;
     }
 
+    if (Ty->isRVVType(/* Bitwidth */ 16, /* IsFloat */ true) &&
+        !Context.getTargetInfo().hasFeature("experimental-zvfh")) {
+      Diag(Loc, diag::err_riscv_type_requires_extension, FD)
+          << Ty << "zvfh";
+    }
+
     // Don't allow SVE types in functions without a SVE target.
     if (Ty->isSVESizelessBuiltinType() && FD && FD->hasBody()) {
       llvm::StringMap<bool> CallerFeatureMap;

clang/lib/Sema/SemaRISCVVectorLookup.cpp

@@ -171,7 +171,6 @@ void RISCVIntrinsicManagerImpl::InitIntrinsicList() {
   const TargetInfo &TI = Context.getTargetInfo();
   bool HasVectorFloat32 = TI.hasFeature("zve32f");
   bool HasVectorFloat64 = TI.hasFeature("zve64d");
-  bool HasZvfh = TI.hasFeature("experimental-zvfh");
   bool HasRV64 = TI.hasFeature("64bit");
   bool HasFullMultiply = TI.hasFeature("v");
 
@@ -223,9 +222,6 @@ void RISCVIntrinsicManagerImpl::InitIntrinsicList() {
         continue;
 
       // Check requirement.
-      if (BaseType == BasicType::Float16 && !HasZvfh)
-        continue;
-
       if (BaseType == BasicType::Float32 && !HasVectorFloat32)
         continue;
 

clang/test/Sema/riscv-vector-float16-check.c

@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -triple riscv64 -target-feature +f -target-feature +d \
+// RUN:   -target-feature +v -target-feature +zfh \
+// RUN:   -disable-O0-optnone -o - -fsyntax-only %s -verify 
+// REQUIRES: riscv-registered-target
+#include <riscv_vector.h>
+
+vfloat16m1_t foo() { /* expected-error {{RISC-V type 'vfloat16m1_t' (aka '__rvv_float16m1_t') requires the 'zvfh' extension}} */
+} /* expected-warning {{non-void function does not return a value}}*/

clang/utils/TableGen/RISCVVEmitter.cpp

@@ -368,14 +368,13 @@ void RVVEmitter::createHeader(raw_ostream &OS) {
       }
     }
   }
-  OS << "#if defined(__riscv_zvfh)\n";
+
   for (int Log2LMUL : Log2LMULs) {
     auto T = TypeCache.computeType(BasicType::Float16, Log2LMUL,
                                    PrototypeDescriptor::Vector);
     if (T)
       printType(*T);
   }
-  OS << "#endif\n";
 
   OS << "#if (__riscv_v_elen_fp >= 32)\n";
   for (int Log2LMUL : Log2LMULs) {