sema: gracefully reject 0-sized IO patch

InputPatch and OutputPatch array size must be greater than 0.
Before this patch we emitted a validation error, which told the
user this was a compiler issue.

Signed-off-by: Nathan Gauër <brioche@google.com>

tools/clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -7884,6 +7884,10 @@ def err_hlsl_node_record_object : Error<
    "object %0 may not appear in a node record">;
 def err_hlsl_array_disallowed : Error<
    "%select{entry parameter|declaration}1 of type %0 may not be an array">;
+def err_hlsl_inputpatch_size: Error<
+   "InputPatch element count must be greater than 0">;
+def err_hlsl_outputpatch_size: Error<
+   "OutputPatch element count must be greater than 0">;
 def note_hlsl_node_array : Note<"'%0' cannot be used as an array; did you mean '%0Array'?">;
 // HLSL Change Ends
 

tools/clang/lib/Sema/SemaHLSL.cpp

@@ -15138,12 +15138,30 @@ void DiagnoseMeshEntry(Sema &S, FunctionDecl *FD, llvm::StringRef StageName) {
   return;
 }
 
+void DiagnoseDomainEntry(Sema &S, FunctionDecl *FD, llvm::StringRef StageName) {
+  for (const auto *param : FD->params()) {
+    if (!hlsl::IsHLSLOutputPatchType(param->getType()))
+      continue;
+    if (hlsl::GetHLSLInputPatchCount(param->getType()) > 0)
+      continue;
+    S.Diags.Report(param->getLocation(), diag::err_hlsl_inputpatch_size);
+  }
+  return;
+}
+
 void DiagnoseHullEntry(Sema &S, FunctionDecl *FD, llvm::StringRef StageName) {
   HLSLPatchConstantFuncAttr *Attr = FD->getAttr<HLSLPatchConstantFuncAttr>();
   if (!Attr)
     S.Diags.Report(FD->getLocation(), diag::err_hlsl_missing_attr)
         << StageName << "patchconstantfunc";
 
+  for (const auto *param : FD->params()) {
+    if (!hlsl::IsHLSLInputPatchType(param->getType()))
+      continue;
+    if (hlsl::GetHLSLInputPatchCount(param->getType()) > 0)
+      continue;
+    S.Diags.Report(param->getLocation(), diag::err_hlsl_inputpatch_size);
+  }
   return;
 }
 
@@ -15570,7 +15588,6 @@ void DiagnoseEntry(Sema &S, FunctionDecl *FD) {
   switch (Stage) {
   case DXIL::ShaderKind::Pixel:
   case DXIL::ShaderKind::Vertex:
-  case DXIL::ShaderKind::Domain:
   case DXIL::ShaderKind::Library:
   case DXIL::ShaderKind::Invalid:
     return;
@@ -15580,6 +15597,8 @@ void DiagnoseEntry(Sema &S, FunctionDecl *FD) {
   case DXIL::ShaderKind::Mesh: {
     return DiagnoseMeshEntry(S, FD, StageName);
   }
+  case DXIL::ShaderKind::Domain:
+    return DiagnoseDomainEntry(S, FD, StageName);
   case DXIL::ShaderKind::Hull: {
     return DiagnoseHullEntry(S, FD, StageName);
   }

tools/clang/test/CodeGenHLSL/ds-error-outputpatch-size.hlsl

@@ -0,0 +1,11 @@
+// RUN: not %dxc -T ds_6_0 -E main %s 2>&1 | FileCheck %s
+
+struct ControlPoint {
+  float position : MY_BOOL;
+};
+
+ControlPoint main(const OutputPatch<ControlPoint, 0> patch) {
+  // CHECK: error: OutputPatch element count must be greater than 0
+  return patch[0];
+}
+

tools/clang/test/CodeGenHLSL/hs-error-inputpatch-size.hlsl

@@ -0,0 +1,22 @@
+// RUN: not %dxc -T hs_6_0 -E main %s 2>&1 | FileCheck %s
+
+struct ControlPoint {
+  float position : MY_BOOL;
+};
+
+struct PatchData {
+    float edge [3] : SV_TessFactor;
+    float inside : SV_InsideTessFactor;
+};
+
+PatchData HullConst () { return (PatchData)0; }
+
+[domain("tri")]
+[partitioning("fractional_odd")]
+[outputtopology("triangle_cw")]
+[patchconstantfunc("HullConst")]
+[outputcontrolpoints(3)]
+ControlPoint main(InputPatch<ControlPoint, 0> v, uint id : SV_OutputControlPointID) {
+  // CHECK: error: InputPatch element count must be greater than 0
+  return v[id];
+}