Allow SV_CullPrimitive on PS input, resolve to false (#2900)

docs/DXIL.rst

@@ -702,7 +702,7 @@ InsideTessFactor       NA           NA       NA           NA           NA
 ViewID                 NotInSig _61 NA       NotInSig _61 NotInSig _61 NA       NA       NA         NotInSig _61 NA       NA       NA       NotInSig _61 NA       NotInSig _61  NA            NA       NotInSig NA       NA        NA
 Barycentrics           NA           NA       NA           NA           NA       NA       NA         NA           NA       NA       NA       NA           NA       NotPacked _61 NA            NA       NA       NA       NA        NA
 ShadingRate            NA           SV _64   NA           NA           SV _64   SV _64   NA         NA           SV _64   SV _64   SV _64   NA           SV _64   SV _64        NA            NA       NA       NA       SV        NA
-CullPrimitive          NA           NA       NA           NA           NA       NA       NA         NA           NA       NA       NA       NA           NA       NA            NA            NA       NA       NA       NotPacked NA
+CullPrimitive          NA           NA       NA           NA           NA       NA       NA         NA           NA       NA       NA       NA           NA       NotInSig      NA            NA       NA       NA       NotPacked NA
 ====================== ============ ======== ============ ============ ======== ======== ========== ============ ======== ======== ======== ============ ======== ============= ============= ======== ======== ======== ========= ========
 
 .. SEMINT-TABLE-RST:END

include/dxc/DXIL/DxilSigPoint.inl

@@ -85,7 +85,7 @@ const SigPoint SigPoint::ms_SigPoints[kNumSigPointRecords] = {
   ROW(ViewID,                 NotInSig _61, NA,       NotInSig _61, NotInSig _61, NA,       NA,       NA,         NotInSig _61, NA,       NA,       NA,       NotInSig _61, NA,       NotInSig _61,  NA,            NA,       NotInSig, NA,       NA,        NA) \
   ROW(Barycentrics,           NA,           NA,       NA,           NA,           NA,       NA,       NA,         NA,           NA,       NA,       NA,       NA,           NA,       NotPacked _61, NA,            NA,       NA,       NA,       NA,        NA) \
   ROW(ShadingRate,            NA,           SV _64,   NA,           NA,           SV _64,   SV _64,   NA,         NA,           SV _64,   SV _64,   SV _64,   NA,           SV _64,   SV _64,        NA,            NA,       NA,       NA,       SV,        NA) \
-  ROW(CullPrimitive,          NA,           NA,       NA,           NA,           NA,       NA,       NA,         NA,           NA,       NA,       NA,       NA,           NA,       NA,            NA,            NA,       NA,       NA,       NotPacked, NA)
+  ROW(CullPrimitive,          NA,           NA,       NA,           NA,           NA,       NA,       NA,         NA,           NA,       NA,       NA,       NA,           NA,       NotInSig,      NA,            NA,       NA,       NA,       NotPacked, NA)
 // INTERPRETATION-TABLE:END
 
 const VersionedSemanticInterpretation SigPoint::ms_SemanticInterpretationTable[(unsigned)DXIL::SemanticKind::Invalid][(unsigned)SigPoint::Kind::Invalid] = {

lib/HLSL/HLSignatureLower.cpp

@@ -141,6 +141,10 @@ void replaceInputOutputWithIntrinsic(DXIL::SemanticKind semKind, Value *GV,
   case Semantic::Kind::GroupIndex:
     opcode = OP::OpCode::FlattenedThreadIdInGroup;
     break;
+  case Semantic::Kind::CullPrimitive: {
+    GV->replaceAllUsesWith(ConstantInt::get(Ty, (uint64_t)0));
+    return;
+  } break;
   default:
     DXASSERT(0, "invalid semantic");
     return;

tools/clang/test/HLSL/system-values.hlsl

@@ -39,6 +39,7 @@
 #define Def_ViewID DECLARE(uint viewID : SV_ViewID) USE(uint, viewID)
 #define Def_Barycentrics DECLARE(float3 BaryWeights : SV_Barycentrics) USE(float, BaryWeights.x) USE(float, BaryWeights.y) USE(float, BaryWeights.z)
 #define Def_ShadingRate DECLARE(uint rate : SV_ShadingRate) USE(uint, rate)
+#define Def_CullPrimitive DECLARE(bool cullprim : SV_CullPrimitive) USE(bool, cullprim)
 
 #define Domain_Quad 0
 #define Domain_Tri 1

tools/clang/test/HLSLFileCheck/hlsl/semantics/sv_cullprimitive/cullprimitive.hlsl

@@ -0,0 +1,13 @@
+// RUN: %dxc -T ps_6_4 -E main %s | FileCheck %s
+
+// SV_CullPrimitive just lowers to false, with nothing in signature
+// CHECK: ; Input signature:
+// CHECK-NEXT: ;
+// CHECK-NEXT: ; Name                 Index   Mask Register SysValue  Format   Used
+// CHECK-NEXT: ; -------------------- ----- ------ -------- -------- ------- ------
+// CHECK-NEXT: ; no parameters
+// CHECK: call void @dx.op.storeOutput.i32(i32 5, i32 0, i32 0, i8 0, i32 0)
+
+uint main(bool b : SV_CullPrimitive) : SV_Target {
+  return b;
+}

utils/hct/hctdb.py

@@ -2267,7 +2267,7 @@ class db_dxil(object):
             ViewID,NotInSig _61,NA,NotInSig _61,NotInSig _61,NA,NA,NA,NotInSig _61,NA,NA,NA,NotInSig _61,NA,NotInSig _61,NA,NA,NotInSig,NA,NA,NA
             Barycentrics,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NotPacked _61,NA,NA,NA,NA,NA,NA
             ShadingRate,NA,SV _64,NA,NA,SV _64,SV _64,NA,NA,SV _64,SV _64,SV _64,NA,SV _64,SV _64,NA,NA,NA,NA,SV,NA
-            CullPrimitive,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NotPacked,NA
+            CullPrimitive,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NA,NotInSig,NA,NA,NA,NA,NotPacked,NA
         """
         table = [list(map(str.strip, line.split(','))) for line in SemanticInterpretationCSV.splitlines() if line.strip()]
         for row in table[1:]: assert(len(row) == len(table[0])) # Ensure table is rectangular