[llvm] [AMDGPU][Attributor] Rework update of `AAAMDWavesPerEU` (PR #123995)

[Johannes Doerfert via llvm-commits]

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@@ -1162,24 +1140,21 @@ struct AAAMDWavesPerEU : public AAAMDSizeRangeAttribute {
       LLVM_DEBUG(dbgs() << '[' << getName() << "] Call " << Caller->getName()
                         << "->" << Func->getName() << '\n');
 
-      const auto *CallerInfo = A.getAAFor<AAAMDWavesPerEU>(
+      const auto *CallerAA = A.getAAFor<AAAMDWavesPerEU>(
           *this, IRPosition::function(*Caller), DepClassTy::REQUIRED);
-      const auto *AssumedGroupSize = A.getAAFor<AAAMDFlatWorkGroupSize>(
-          *this, IRPosition::function(*Func), DepClassTy::REQUIRED);
-      if (!CallerInfo || !AssumedGroupSize || !CallerInfo->isValidState() ||
-          !AssumedGroupSize->isValidState())
+      if (!CallerAA || !CallerAA->isValidState())
         return false;
 
-      unsigned Min, Max;
-      std::tie(Min, Max) = InfoCache.getEffectiveWavesPerEU(
-          *Caller,
-          {CallerInfo->getAssumed().getLower().getZExtValue(),
-           CallerInfo->getAssumed().getUpper().getZExtValue() - 1},
-          {AssumedGroupSize->getAssumed().getLower().getZExtValue(),
-           AssumedGroupSize->getAssumed().getUpper().getZExtValue() - 1});
-      ConstantRange CallerRange(APInt(32, Min), APInt(32, Max + 1));
-      IntegerRangeState CallerRangeState(CallerRange);
-      Change |= clampStateAndIndicateChange(this->getState(), CallerRangeState);
+      ConstantRange Assumed = this->getAssumed();
+      unsigned Min = std::max(Assumed.getLower().getZExtValue(),
+                              CallerAA->getAssumed().getLower().getZExtValue());
+      unsigned Max = std::max(Assumed.getUpper().getZExtValue(),
+                              CallerAA->getAssumed().getUpper().getZExtValue());
+      ConstantRange Range(APInt(32, Min), APInt(32, Max));
+      IntegerRangeState RangeState(Range);
+      this->getState() = RangeState;
+      Change |= this->getState() == Assumed ? ChangeStatus::UNCHANGED
+                                            : ChangeStatus::CHANGED;
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jdoerfert wrote:

Nit: Do we really need the `this->` uses above?

https://github.com/llvm/llvm-project/pull/123995