[HLSL][DirectX] Add verifyNumDescriptors

Author: inbelic

llvm/include/llvm/Frontend/HLSL/RootSignatureValidations.h

@@ -31,6 +31,7 @@ bool verifyDescriptorFlag(uint32_t Flags);
 bool verifyRangeType(uint32_t Type);
 bool verifyDescriptorRangeFlag(uint32_t Version, uint32_t Type,
                                uint32_t FlagsVal);
+bool verifyNumDescriptors(uint32_t NumDescriptors);
 bool verifySamplerFilter(uint32_t Value);
 bool verifyAddress(uint32_t Address);
 bool verifyMipLODBias(float MipLODBias);

llvm/lib/Frontend/HLSL/RootSignatureValidations.cpp

@@ -108,6 +108,10 @@ bool verifyDescriptorRangeFlag(uint32_t Version, uint32_t Type,
   return (Flags & ~Mask) == FlagT::None;
 }
 
+bool verifyNumDescriptors(uint32_t NumDescriptors) {
+  return NumDescriptors > 0;
+}
+
 bool verifySamplerFilter(uint32_t Value) {
   switch (Value) {
 #define FILTER(Num, Val) case llvm::to_underlying(dxbc::SamplerFilter::Val):

llvm/lib/Target/DirectX/DXILRootSignature.cpp

@@ -447,6 +447,9 @@ static bool validate(LLVMContext *Ctx, const mcdxbc::RootSignatureDesc &RSD) {
         if (!llvm::hlsl::rootsig::verifyRegisterSpace(Range.RegisterSpace))
           return reportValueError(Ctx, "RegisterSpace", Range.RegisterSpace);
 
+        if (!llvm::hlsl::rootsig::verifyNumDescriptors(Range.NumDescriptors))
+          return reportValueError(Ctx, "NumDescriptors", Range.NumDescriptors);
+
         if (!llvm::hlsl::rootsig::verifyDescriptorRangeFlag(
                 RSD.Version, Range.RangeType, Range.Flags))
           return reportValueError(Ctx, "DescriptorFlag", Range.Flags);

llvm/test/CodeGen/DirectX/ContainerData/RootSignature-DescriptorTable-Invalid-NumDescriptors.ll

@@ -0,0 +1,19 @@
+; RUN: not opt -passes='print<dxil-root-signature>' %s -S -o - 2>&1 | FileCheck %s
+
+target triple = "dxil-unknown-shadermodel6.0-compute"
+
+; CHECK: error: Invalid value for NumDescriptors: 0
+; CHECK-NOT: Root Signature Definitions
+
+define void @main() #0 {
+entry:
+  ret void
+}
+attributes #0 = { "hlsl.numthreads"="1,1,1" "hlsl.shader"="compute" }
+
+
+!dx.rootsignatures = !{!2} ; list of function/root signature pairs
+!2 = !{ ptr @main, !3, i32 2 } ; function, root signature
+!3 = !{ !5 } ; list of root signature elements
+!5 = !{ !"DescriptorTable", i32 0, !6}
+!6 = !{ !"SRV", i32 0, i32 0, i32 10, i32 -1, i32 4 }