[llvm] [AMDGPU][SIInsertWaitcnts][NFC] Introduce Counter class (PR #190271)

[via llvm-commits]

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@@ -742,14 +743,65 @@ class WaitcntBrackets {
   bool empty(InstCounterType T) const { return getScoreRange(T) == 0; }
 
 private:
+  /// A container that holds all counters.
+  class AllCounters {
+    /// A counter of a specific InstCounterType. Whenever this pass visits an
+    /// instruction that affects this counter type we "increment" the counter.
+    /// Conceptually the counter implements the value of the corresponding
+    /// AMDGPU hardware counter if none of the outstanding instructions that
+    /// affect this counter had completed. When a wait for this counter is
+    /// emitted then we "decrement" (or zero) the counter.
+    class Counter {
+      InstCounterType CntT;
+      const AMDGPU::HardwareLimits *Limits = nullptr;
+      unsigned LB = 0;
+      unsigned UB = 0;
+
+    public:
+      Counter() = default;
+      Counter(InstCounterType CntT, const AMDGPU::HardwareLimits &Limits)
+          : CntT(CntT), Limits(&Limits) {}
+      /// \returns the count of outstanding instrs tracked by this counter.
+      unsigned getValue() const { return UB - LB; }
+      // TODO: Make private: we should not provide raw access to the internals.
+      void setLB(unsigned NewLB) { LB = NewLB; }
+      // TODO: Make private: we should not provide raw access to the internals.
+      void setUB(unsigned NewUB) {
+        UB = NewUB;
+        if (CntT == EXP_CNT) {
+          if (getValue() > getWaitCountMax(*Limits, EXP_CNT))
+            LB = UB - getWaitCountMax(*Limits, EXP_CNT);
+        }
+      }
+      // TODO: Make private: we should not provide raw access to the internals.
+      unsigned getUB() const { return UB; }
+      // TODO: Make private: we should not provide raw access to the internals.
+      unsigned getLB() const { return LB; }
+
+      /// \returns true if the counter includes \p Score, i.e., it has
+      /// contributed to its current value, or in other words it is pending.
+      bool contains(unsigned Score) const { return LB < Score && Score <= UB; }
+    };
+
+    std::array<Counter, NUM_INST_CNTS> Counters;
+
+  public:
+    explicit AllCounters(const AMDGPU::HardwareLimits &Limits) {
+      for (InstCounterType CntT : inst_counter_types())
+        Counters[(int)CntT] = Counter(CntT, Limits);
+    }
+    Counter &operator[](unsigned Idx) { return Counters[Idx]; }
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vporpo wrote:

Good point, done.

https://github.com/llvm/llvm-project/pull/190271