[llvm] [DirectX] Infrastructure to collect shader flags for each function (PR #112967)

[S. Bharadwaj Yadavalli via llvm-commits]

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@@ -63,16 +115,53 @@ void ComputedShaderFlags::print(raw_ostream &OS) const {
   OS << ";\n";
 }
 
+void DXILModuleShaderFlagsInfo::print(raw_ostream &OS) const {
+  OS << "; Shader Flags mask for Module:\n";
+  ModuleFlags.print(OS);
+  for (auto SF : FuncShaderFlagsVec) {
+    OS << "; Shader Flags mask for Function: " << SF.first->getName() << "\n";
+    SF.second.print(OS);
+  }
+}
+
+const ComputedShaderFlags
+DXILModuleShaderFlagsInfo::getShaderFlagsMask(const Function *Func) const {
+  FuncShaderFlagsMask V{Func, {}};
+  auto Iter = llvm::lower_bound(FuncShaderFlagsVec, V, compareFuncSFPairs);
+  if (Iter == FuncShaderFlagsVec.end()) {
+    Func->getContext().diagnose(DiagnosticInfoShaderFlags(
+        *(Func->getParent()), "Shader Flags information of Function '" +
+                                  Twine(Func->getName()) + "' not found"));
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bharadwajy wrote:

> > When can this happen? Does it actually indicate a bug in the code or is there some input that someone could generate that would cause this diagnostic to get emitted?
> 
> Since this is the method used by other passes to query for shader flags mask for a function, a failed query is reported as a diagnostic. If the preference is to return a value indicating an error - allowing the caller to determine the consequences - I am open to that as well.

Changed return type to `Expected<T>` and deleted `class DiagnosticInfoShaderFlags`.

https://github.com/llvm/llvm-project/pull/112967