removing unnecessary parameters

Author: joaosaffran

llvm/include/llvm/Object/DXContainer.h

@@ -170,13 +170,12 @@ class RootSignature {
   uint32_t StaticSamplersOffset;
   uint32_t Flags;
   ViewArray<dxbc::RootParameterHeader> ParametersHeaders;
-  uint32_t ParameterSpaceOffset;
-  StringRef ParameterSpace;
+  StringRef PartData;
 
   using param_header_iterator = ViewArray<dxbc::RootParameterHeader>::iterator;
 
 public:
-  RootSignature() {}
+  RootSignature(StringRef PD) : PartData(PD) {}
 
   Error parse(StringRef Data);
   uint32_t getVersion() const { return Version; }
@@ -191,23 +190,22 @@ class RootSignature {
 
   llvm::Expected<RootParameterView>
   getParameter(const dxbc::RootParameterHeader &Header) const {
-    assert(ParameterSpaceOffset != 0 &&
-           "This should be initialized before reading parameters");
-    size_t CorrectOffset = Header.ParameterOffset - ParameterSpaceOffset;
-    StringRef Data;
     size_t DataSize;
 
     switch (Header.ParameterType) {
     case dxbc::RootParameterType::Constants32Bit:
       DataSize = sizeof(dxbc::RootConstants);
       break;
     }
+    auto EndOfSectionByte = getNumStaticSamplers() == 0
+                                ? PartData.size()
+                                : getStaticSamplersOffset();
 
-    if (CorrectOffset + DataSize > ParameterSpace.size())
+    if (Header.ParameterOffset + DataSize > EndOfSectionByte)
       return parseFailed("Reading structure out of file bounds");
 
-    Data = ParameterSpace.substr(CorrectOffset, DataSize);
-    RootParameterView View = RootParameterView(Header, Data);
+    StringRef Buff = PartData.substr(Header.ParameterOffset, DataSize);
+    RootParameterView View = RootParameterView(Header, Buff);
     return View;
   }
 };

llvm/lib/Object/DXContainer.cpp

@@ -96,7 +96,7 @@ Error DXContainer::parseHash(StringRef Part) {
 Error DXContainer::parseRootSignature(StringRef Part) {
   if (RootSignature)
     return parseFailed("More than one RTS0 part is present in the file");
-  RootSignature = DirectX::RootSignature();
+  RootSignature = DirectX::RootSignature(Part);
   if (Error Err = RootSignature->parse(Part))
     return Err;
   return Error::success();
@@ -278,14 +278,6 @@ Error DirectX::RootSignature::parse(StringRef Data) {
   ParametersHeaders.Data = Data.substr(
       RootParametersOffset, NumParameters * sizeof(dxbc::RootParameterHeader));
 
-  ParameterSpaceOffset =
-      RootParametersOffset + NumParameters * sizeof(dxbc::RootParameterHeader);
-  size_t ParameterSpaceEnd =
-      (NumStaticSamplers == 0) ? Data.size() : StaticSamplersOffset;
-
-  ParameterSpace = Data.substr(ParameterSpaceOffset,
-                               ParameterSpaceEnd - ParameterSpaceOffset);
-
   return Error::success();
 }