[clang] Implement resource binding type prefix mismatch flag setting logic (PR #97103)

[Damyan Pepper via cfe-commits]

================
@@ -437,7 +460,406 @@ void SemaHLSL::handleShaderAttr(Decl *D, const ParsedAttr &AL) {
     D->addAttr(NewAttr);
 }
 
+struct register_binding_flags {
+  bool resource = false;
+  bool udt = false;
+  bool other = false;
+  bool basic = false;
+
+  bool srv = false;
+  bool uav = false;
+  bool cbv = false;
+  bool sampler = false;
+
+  bool contains_numeric = false;
+  bool default_globals = false;
+};
+
+bool isDeclaredWithinCOrTBuffer(const Decl *decl) {
+  if (!decl)
+    return false;
+
+  // Traverse up the parent contexts
+  const DeclContext *context = decl->getDeclContext();
+  while (context) {
+    if (isa<HLSLBufferDecl>(context)) {
+      return true;
+    }
+    context = context->getParent();
+  }
+
+  return false;
+}
+
+const CXXRecordDecl *getRecordDeclFromVarDecl(VarDecl *SamplerUAVOrSRV) {
+  const Type *Ty = SamplerUAVOrSRV->getType()->getPointeeOrArrayElementType();
+  if (!Ty)
+    llvm_unreachable("Resource class must have an element type.");
+
+  if (const BuiltinType *BTy = dyn_cast<BuiltinType>(Ty)) {
+    return nullptr;
+  }
+
+  const CXXRecordDecl *TheRecordDecl = Ty->getAsCXXRecordDecl();
+  if (!TheRecordDecl)
+    llvm_unreachable("Resource class should have a resource type declaration.");
+
+  if (auto TDecl = dyn_cast<ClassTemplateSpecializationDecl>(TheRecordDecl))
+    TheRecordDecl = TDecl->getSpecializedTemplate()->getTemplatedDecl();
+  TheRecordDecl = TheRecordDecl->getCanonicalDecl();
+  return TheRecordDecl;
+}
+
+const HLSLResourceAttr *
+getHLSLResourceAttrFromEitherDecl(VarDecl *SamplerUAVOrSRV,
+                                  HLSLBufferDecl *CBufferOrTBuffer) {
+
+  if (SamplerUAVOrSRV) {
+    const CXXRecordDecl *TheRecordDecl =
+        getRecordDeclFromVarDecl(SamplerUAVOrSRV);
+    if (!TheRecordDecl)
+      return nullptr;
+    const auto *Attr = TheRecordDecl->getAttr<HLSLResourceAttr>();
+    return Attr;
+  } else if (CBufferOrTBuffer) {
+    const auto *Attr = CBufferOrTBuffer->getAttr<HLSLResourceAttr>();
+    return Attr;
+  }
+  llvm_unreachable("one of the two conditions should be true.");
+  return nullptr;
+}
+
+void traverseType(QualType T, register_binding_flags &r) {
+  if (T->isIntegralOrEnumerationType() || T->isFloatingType()) {
+    r.contains_numeric = true;
+    return;
+  } else if (const RecordType *RT = T->getAs<RecordType>()) {
+    RecordDecl *SubRD = RT->getDecl();
+    if (auto TDecl = dyn_cast<ClassTemplateSpecializationDecl>(SubRD)) {
+      auto TheRecordDecl = TDecl->getSpecializedTemplate()->getTemplatedDecl();
+      TheRecordDecl = TheRecordDecl->getCanonicalDecl();
+      const auto *Attr = TheRecordDecl->getAttr<HLSLResourceAttr>();
+      llvm::hlsl::ResourceClass DeclResourceClass = Attr->getResourceClass();
+      switch (DeclResourceClass) {
+      case llvm::hlsl::ResourceClass::SRV: {
+        r.srv = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::UAV: {
+        r.uav = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::CBuffer: {
+        r.cbv = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::Sampler: {
+        r.sampler = true;
+        break;
+      }
+      }
+    }
+
+    else if (SubRD->isCompleteDefinition()) {
+      for (auto Field : SubRD->fields()) {
+        QualType T = Field->getType();
+        traverseType(T, r);
+      }
+    }
+  }
+}
+
+void setResourceClassFlagsFromRecordDecl(register_binding_flags &r,
+                                         const RecordDecl *RD) {
+  if (!RD)
+    return;
+
+  if (RD->isCompleteDefinition()) {
+    for (auto Field : RD->fields()) {
+      QualType T = Field->getType();
+      traverseType(T, r);
+    }
+  }
+}
+
+register_binding_flags HLSLFillRegisterBindingFlags(Sema &S, Decl *D) {
+  register_binding_flags r;
+  if (!isDeclaredWithinCOrTBuffer(D)) {
+    // make sure the type is a basic / numeric type
+    if (VarDecl *v = dyn_cast<VarDecl>(D)) {
+      QualType t = v->getType();
+      // a numeric variable will inevitably end up in $Globals buffer
+      if (t->isIntegralType(S.getASTContext()) || t->isFloatingType())
+        r.default_globals = true;
+    }
+  }
+  // Cbuffers and Tbuffers are HLSLBufferDecl types
+  HLSLBufferDecl *CBufferOrTBuffer = dyn_cast<HLSLBufferDecl>(D);
+  // Samplers, UAVs, and SRVs are VarDecl types
+  VarDecl *SamplerUAVOrSRV = dyn_cast<VarDecl>(D);
+
+  if (CBufferOrTBuffer) {
+    r.resource = true;
+    if (CBufferOrTBuffer->isCBuffer())
+      r.cbv = true;
+    else
+      r.srv = true;
+  } else if (SamplerUAVOrSRV) {
+    const HLSLResourceAttr *res_attr =
+        getHLSLResourceAttrFromEitherDecl(SamplerUAVOrSRV, CBufferOrTBuffer);
+    if (res_attr) {
+      llvm::hlsl::ResourceClass DeclResourceClass =
+          res_attr->getResourceClass();
+      r.resource = true;
+      switch (DeclResourceClass) {
+      case llvm::hlsl::ResourceClass::SRV: {
+        r.srv = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::UAV: {
+        r.uav = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::CBuffer: {
+        r.cbv = true;
+        break;
+      }
+      case llvm::hlsl::ResourceClass::Sampler: {
+        r.sampler = true;
+        break;
+      }
+      }
+    } else {
+      if (SamplerUAVOrSRV->getType()->isBuiltinType())
+        r.basic = true;
+      else if (SamplerUAVOrSRV->getType()->isAggregateType()) {
+        r.udt = true;
+        QualType VarType = SamplerUAVOrSRV->getType();
+        if (const RecordType *RT = VarType->getAs<RecordType>()) {
+          const RecordDecl *RD = RT->getDecl();
+          // recurse through members, set appropriate resource class flags.
+          setResourceClassFlagsFromRecordDecl(r, RD);
+        }
+      } else
+        r.other = true;
+    }
+  } else {
+    llvm_unreachable("unknown decl type");
+  }
+  return r;
+}
+
+static void ValidateMultipleRegisterAnnotations(Sema &S, Decl *D,
+                                                StringRef &Slot) {
+  // make sure that there are no register annotations applied to the decl
+  // with the same register type but different numbers
----------------
damyanp wrote:

I was having a closer look at this because `unordered_map`s always ring alarm bells for me and `unordered_map`s of `sets`s ring those bells double time.

I think that this function is jumping through a lot of hoops to make e1 below be accepted while e2 is rejected:

```
Eg e1 : register(u9) : register(u9); // accepted
Eg e2 : register(u9) : register(u10); // error
```

Is that right?  I don't see any test cases equivalent to the e1 case.

I'd question if there's much purpose in putting a lot of energy into supporting this, as opposed to just rejecting anything where there is more than one annotation for the same register type.

https://github.com/llvm/llvm-project/pull/97103