[HLSL] Add Load overload with status (#166449)

This PR adds a Load method for resources, which takes an additional
parameter by reference, status. It fills the status parameter with a 1
or 0, depending on whether or not the resource access was mapped.
CheckAccessFullyMapped is also added as an intrinsic, and called in the
production of this status bit.
Only addresses DXIL for the below issue:
https://github.com/llvm/llvm-project/issues/138910
Also only addresses the DXIL variant for the below issue:
https://github.com/llvm/llvm-project/issues/99204

1 files changed, 28 insertions, 1 deletions

diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
index ce6e8121b9d9..e0049dc75c0d 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
@@ -100,6 +100,26 @@ static bool checkWaveOps(Intrinsic::ID IID) {
   }
 }
 
+// Checks to see if the status bit from a load with status
+// instruction is ever extracted. If it is, the module needs
+// to have the TiledResources shader flag set.
+bool checkIfStatusIsExtracted(const IntrinsicInst &II) {
+  [[maybe_unused]] Intrinsic::ID IID = II.getIntrinsicID();
+  assert(IID == Intrinsic::dx_resource_load_typedbuffer ||
+         IID == Intrinsic::dx_resource_load_rawbuffer &&
+             "unexpected intrinsic ID");
+  for (const User *U : II.users()) {
+    if (const ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(U)) {
+      // Resource load operations return a {result, status} pair.
+      // Check if we extract the status
+      if (EVI->getNumIndices() == 1 && EVI->getIndices()[0] == 1)
+        return true;
+    }
+  }
+
+  return false;
+}
+
 /// Update the shader flags mask based on the given instruction.
 /// \param CSF Shader flags mask to update.
 /// \param I Instruction to check.
@@ -164,7 +184,7 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
     }
   }
 
-  if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
+  if (const auto *II = dyn_cast<IntrinsicInst>(&I)) {
     switch (II->getIntrinsicID()) {
     default:
       break;
@@ -192,6 +212,13 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
           DRTM[cast<TargetExtType>(II->getArgOperand(0)->getType())];
       if (RTI.isTyped())
         CSF.TypedUAVLoadAdditionalFormats |= RTI.getTyped().ElementCount > 1;
+      if (!CSF.TiledResources && checkIfStatusIsExtracted(*II))
+        CSF.TiledResources = true;
+      break;
+    }
+    case Intrinsic::dx_resource_load_rawbuffer: {
+      if (!CSF.TiledResources && checkIfStatusIsExtracted(*II))
+        CSF.TiledResources = true;
       break;
     }
     }