review: remove redundant Index to Element mapping

Author: inbelic

clang/lib/Sema/SemaHLSL.cpp

@@ -1086,9 +1086,8 @@ bool SemaHLSL::handleRootSignatureElements(
   using RangeInfo = llvm::hlsl::rootsig::RangeInfo;
   using OverlappingRanges = llvm::hlsl::rootsig::OverlappingRanges;
 
-  // Introduce a mapping from the collected RangeInfos back to the
-  // RootSignatureElement that will retain its diagnostics info
-  llvm::DenseMap<size_t, const hlsl::RootSignatureElement *> InfoIndexMap;
+  // Each RangeInfo will contain an index back to its associated
+  // RootSignatureElement in our Elements ArrayRef
   size_t InfoIndex = 0;
 
   // 1. Collect RangeInfos
@@ -1106,8 +1105,7 @@ bool SemaHLSL::handleRootSignatureElements(
       Info.Space = Descriptor->Space;
       Info.Visibility = Descriptor->Visibility;
 
-      Info.Index = InfoIndex++;
-      InfoIndexMap[Info.Index] = &RootSigElem;
+      Info.Index = InfoIndex;
       Infos.push_back(Info);
     } else if (const auto *Constants =
                    std::get_if<llvm::hlsl::rootsig::RootConstants>(&Elem)) {
@@ -1119,8 +1117,7 @@ bool SemaHLSL::handleRootSignatureElements(
       Info.Space = Constants->Space;
       Info.Visibility = Constants->Visibility;
 
-      Info.Index = InfoIndex++;
-      InfoIndexMap[Info.Index] = &RootSigElem;
+      Info.Index = InfoIndex;
       Infos.push_back(Info);
     } else if (const auto *Sampler =
                    std::get_if<llvm::hlsl::rootsig::StaticSampler>(&Elem)) {
@@ -1132,8 +1129,7 @@ bool SemaHLSL::handleRootSignatureElements(
       Info.Space = Sampler->Space;
       Info.Visibility = Sampler->Visibility;
 
-      Info.Index = InfoIndex++;
-      InfoIndexMap[Info.Index] = &RootSigElem;
+      Info.Index = InfoIndex;
       Infos.push_back(Info);
     } else if (const auto *Clause =
                    std::get_if<llvm::hlsl::rootsig::DescriptorTableClause>(
@@ -1150,8 +1146,7 @@ bool SemaHLSL::handleRootSignatureElements(
       Info.Space = Clause->Space;
 
       // Note: Clause does not hold the visibility this will need to
-      Info.Index = InfoIndex++;
-      InfoIndexMap[Info.Index] = &RootSigElem;
+      Info.Index = InfoIndex;
       Infos.push_back(Info);
     } else if (const auto *Table =
                    std::get_if<llvm::hlsl::rootsig::DescriptorTable>(&Elem)) {
@@ -1165,17 +1160,18 @@ bool SemaHLSL::handleRootSignatureElements(
       for (RangeInfo &Info : TableInfos)
         Info.Visibility = Table->Visibility;
     }
+
+    InfoIndex++;
   }
 
   // Helper to report diagnostics
-  auto ReportOverlap = [this, &InfoIndexMap](OverlappingRanges Overlap) {
+  auto ReportOverlap = [this, &Elements](OverlappingRanges Overlap) {
     const RangeInfo *Info = Overlap.A;
     const RangeInfo *OInfo = Overlap.B;
     auto CommonVis = Info->Visibility == llvm::dxbc::ShaderVisibility::All
                          ? OInfo->Visibility
                          : Info->Visibility;
-    const hlsl::RootSignatureElement *Elem = InfoIndexMap.at(Info->Index);
-    SourceLocation InfoLoc = Elem->getLocation();
+    SourceLocation InfoLoc = Elements[Info->Index].getLocation();
     this->Diag(InfoLoc, diag::err_hlsl_resource_range_overlap)
         << llvm::to_underlying(Info->Class) << Info->LowerBound
         << /*unbounded=*/(Info->UpperBound == RangeInfo::Unbounded)
@@ -1184,8 +1180,7 @@ bool SemaHLSL::handleRootSignatureElements(
         << /*unbounded=*/(OInfo->UpperBound == RangeInfo::Unbounded)
         << OInfo->UpperBound << Info->Space << CommonVis;
 
-    const hlsl::RootSignatureElement *OElem = InfoIndexMap.at(OInfo->Index);
-    SourceLocation OInfoLoc = OElem->getLocation();
+    SourceLocation OInfoLoc = Elements[OInfo->Index].getLocation();
     this->Diag(OInfoLoc, diag::note_hlsl_resource_range_here);
   };