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

[S. Bharadwaj Yadavalli via llvm-commits]

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@@ -63,17 +114,63 @@ void ComputedShaderFlags::print(raw_ostream &OS) const {
   OS << ";\n";
 }
 
+/// Insert the pair <Func, FlagMask> into the sorted vector
+/// FunctionFlags. The insertion is expected to be in-order and hence
+/// is done at the end of the already sorted list.
+void DXILModuleShaderFlagsInfo::insertInorderFunctionFlags(
+    const Function *Func, ComputedShaderFlags FlagMask) {
+  FunctionFlags.push_back({Func, FlagMask});
+}
+
+const SmallVector<std::pair<Function const *, ComputedShaderFlags>> &
+DXILModuleShaderFlagsInfo::getFunctionFlags() const {
+  return FunctionFlags;
+}
+
+const ComputedShaderFlags &DXILModuleShaderFlagsInfo::getModuleFlags() const {
+  return ModuleFlags;
+}
+
+Expected<const ComputedShaderFlags &>
+DXILModuleShaderFlagsInfo::getShaderFlagsMask(const Function *Func) const {
+  std::pair<Function const *, ComputedShaderFlags> V{Func, {}};
+  const auto *Iter = llvm::lower_bound(FunctionFlags, V);
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bharadwajy wrote:

> Does this really return a pointer? I'd expect it to return an instance of an iterator as a value type.

`clang-tidy` suggested `const auto *` vs `const auto` - although either is fine. I used `const auto *` since it seemed to be a reasonable suggestion given `Iter` points to the content and is accessed using `->`. However, looks like the convention in LLVM is not to use `*`. So, changed to `const auto`.

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