[llvm] [HLSL] Analyze update counter usage (PR #130356)

[Ashley Coleman via llvm-commits]

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@@ -823,8 +827,153 @@ DXILBindingMap::findByUse(const Value *Key) const {
 
 //===----------------------------------------------------------------------===//
 
+static bool isUpdateCounterIntrinsic(Function &F) {
+  return F.getIntrinsicID() == Intrinsic::dx_resource_updatecounter;
+}
+
+void DXILResourceCounterDirectionMap::populate(Module &M, DXILBindingMap &DBM) {
+  std::vector<std::tuple<dxil::ResourceBindingInfo, ResourceCounterDirection,
+                         const Function *, const CallInst *>>
+      DiagCounterDirs;
+
+  for (Function &F : M.functions()) {
+    if (!isUpdateCounterIntrinsic(F))
+      continue;
+
+    for (const User *U : F.users()) {
+      const CallInst *CI = dyn_cast<CallInst>(U);
+      assert(CI && "Users of dx_resource_updateCounter must be call instrs");
+
+      // Determine if the use is an increment or decrement
+      Value *CountArg = CI->getArgOperand(1);
+      ConstantInt *CountValue = dyn_cast<ConstantInt>(CountArg);
+      int64_t CountLiteral = CountValue->getSExtValue();
+
+      ResourceCounterDirection Direction = ResourceCounterDirection::Unknown;
+      if (CountLiteral > 0)
+        Direction = ResourceCounterDirection::Increment;
+      if (CountLiteral < 0)
----------------
V-FEXrt wrote:

imo `else` (and extra so for `else if`)  harms readability because you have to keep  the context of the negation  of the previous `if` in your head to tease out the logic. Happy to make the change but my default programming habit is to minimize the use of else as much as possible without writing extra wonky code

https://github.com/llvm/llvm-project/pull/130356