[SelectOpt] Add handling for not conditions.

llvm/lib/CodeGen/SelectOptimize.cpp

@@ -130,7 +130,11 @@ class SelectOptimizeImpl {
   class SelectLike {
     SelectLike(Instruction *I) : I(I) {}
 
+    /// The select (/or) instruction.
     Instruction *I;
+    /// Whether this select is inverted, "not(cond), FalseVal, TrueVal", as
+    /// opposed to the original condition.
+    bool Inverted = false;
 
   public:
     /// Match a select or select-like instruction, returning a SelectLike.
@@ -153,14 +157,22 @@ class SelectOptimizeImpl {
     bool isValid() { return I; }
     operator bool() { return isValid(); }
 
+    /// Invert the select by inverting the condition and switching the operands.
+    void setInverted() {
+      assert(!Inverted && "Trying to invert an inverted SelectLike");
+      assert(isa<Instruction>(getCondition()) &&
+             cast<Instruction>(getCondition())->getOpcode() ==
+                 Instruction::Xor);
+      Inverted = true;
+    }
+    bool isInverted() const { return Inverted; }
+
     Instruction *getI() { return I; }
     const Instruction *getI() const { return I; }
 
     Type *getType() const { return I->getType(); }
 
-    /// Return the condition for the SelectLike instruction. For example the
-    /// condition of a select or c in `or(zext(c), x)`
-    Value *getCondition() const {
+    Value *getNonInvertedCondition() const {
       if (auto *Sel = dyn_cast<SelectInst>(I))
         return Sel->getCondition();
       // Or(zext) case
@@ -177,11 +189,24 @@ class SelectOptimizeImpl {
       llvm_unreachable("Unhandled case in getCondition");
     }
 
+    /// Return the condition for the SelectLike instruction. For example the
+    /// condition of a select or c in `or(zext(c), x)`
+    Value *getCondition() const {
+      Value *CC = getNonInvertedCondition();
+      // For inverted conditions the CC is checked when created to be a not
+      // (xor) instruction.
+      if (Inverted)
+        return cast<Instruction>(CC)->getOperand(0);
+      return CC;
+    }
+
     /// Return the true value for the SelectLike instruction. Note this may not
     /// exist for all SelectLike instructions. For example, for `or(zext(c), x)`
     /// the true value would be `or(x,1)`. As this value does not exist, nullptr
     /// is returned.
-    Value *getTrueValue() const {
+    Value *getTrueValue(bool HonorInverts = true) const {
+      if (Inverted && HonorInverts)
+        return getFalseValue(/*HonorInverts=*/false);
       if (auto *Sel = dyn_cast<SelectInst>(I))
         return Sel->getTrueValue();
       // Or(zext) case - The true value is Or(X), so return nullptr as the value
@@ -195,7 +220,9 @@ class SelectOptimizeImpl {
     /// Return the false value for the SelectLike instruction. For example the
     /// getFalseValue of a select or `x` in `or(zext(c), x)` (which is
     /// `select(c, x|1, x)`)
-    Value *getFalseValue() const {
+    Value *getFalseValue(bool HonorInverts = true) const {
+      if (Inverted && HonorInverts)
+        return getTrueValue(/*HonorInverts=*/false);
       if (auto *Sel = dyn_cast<SelectInst>(I))
         return Sel->getFalseValue();
       // Or(zext) case - return the operand which is not the zext.
@@ -216,8 +243,8 @@ class SelectOptimizeImpl {
     /// InstCostMap. This may need to be generated for select-like instructions.
     Scaled64 getTrueOpCost(DenseMap<const Instruction *, CostInfo> &InstCostMap,
                            const TargetTransformInfo *TTI) {
-      if (auto *Sel = dyn_cast<SelectInst>(I))
-        if (auto *I = dyn_cast<Instruction>(Sel->getTrueValue()))
+      if (isa<SelectInst>(I))
+        if (auto *I = dyn_cast<Instruction>(getTrueValue()))
           return InstCostMap.contains(I) ? InstCostMap[I].NonPredCost
                                          : Scaled64::getZero();
 
@@ -242,8 +269,8 @@ class SelectOptimizeImpl {
     Scaled64
     getFalseOpCost(DenseMap<const Instruction *, CostInfo> &InstCostMap,
                    const TargetTransformInfo *TTI) {
-      if (auto *Sel = dyn_cast<SelectInst>(I))
-        if (auto *I = dyn_cast<Instruction>(Sel->getFalseValue()))
+      if (isa<SelectInst>(I))
+        if (auto *I = dyn_cast<Instruction>(getFalseValue()))
           return InstCostMap.contains(I) ? InstCostMap[I].NonPredCost
                                          : Scaled64::getZero();
 
@@ -510,9 +537,10 @@ getTrueOrFalseValue(SelectOptimizeImpl::SelectLike SI, bool isTrue,
   for (SelectInst *DefSI = dyn_cast<SelectInst>(SI.getI());
        DefSI != nullptr && Selects.count(DefSI);
        DefSI = dyn_cast<SelectInst>(V)) {
-    assert(DefSI->getCondition() == SI.getCondition() &&
-           "The condition of DefSI does not match with SI");
-    V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
+    if (DefSI->getCondition() == SI.getCondition())
+      V = (isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
+    else // Handle inverted SI
+      V = (!isTrue ? DefSI->getTrueValue() : DefSI->getFalseValue());
   }
 
   if (isa<BinaryOperator>(SI.getI())) {
@@ -632,18 +660,19 @@ void SelectOptimizeImpl::convertProfitableSIGroups(SelectGroups &ProfSIGroups) {
     // Delete the unconditional branch that was just created by the split.
     StartBlock->getTerminator()->eraseFromParent();
 
-    // Move any debug/pseudo instructions that were in-between the select
-    // group to the newly-created end block.
-    SmallVector<Instruction *, 2> DebugPseudoINS;
+    // Move any debug/pseudo instructions and not's that were in-between the
+    // select group to the newly-created end block.
+    SmallVector<Instruction *, 2> SinkInstrs;
     auto DIt = SI.getI()->getIterator();
     while (&*DIt != LastSI.getI()) {
       if (DIt->isDebugOrPseudoInst())
-        DebugPseudoINS.push_back(&*DIt);
+        SinkInstrs.push_back(&*DIt);
+      if (match(&*DIt, m_Not(m_Specific(SI.getCondition()))))
+        SinkInstrs.push_back(&*DIt);
       DIt++;
     }
-    for (auto *DI : DebugPseudoINS) {
+    for (auto *DI : SinkInstrs)
       DI->moveBeforePreserving(&*EndBlock->getFirstInsertionPt());
-    }
 
     // Duplicate implementation for DbgRecords, the non-instruction debug-info
     // format. Helper lambda for moving DbgRecords to the end block.
@@ -765,6 +794,13 @@ void SelectOptimizeImpl::collectSelectGroups(BasicBlock &BB,
           ++BBIt;
           continue;
         }
+
+        // Skip not(select(..)), if the not is part of the same select group
+        if (match(NI, m_Not(m_Specific(SI.getCondition())))) {
+          ++BBIt;
+          continue;
+        }
+
         // We only allow selects in the same group, not other select-like
         // instructions.
         if (!isa<SelectInst>(NI))
@@ -773,6 +809,10 @@ void SelectOptimizeImpl::collectSelectGroups(BasicBlock &BB,
         SelectLike NSI = SelectLike::match(NI);
         if (NSI && SI.getCondition() == NSI.getCondition()) {
           SIGroup.push_back(NSI);
+        } else if (NSI && match(NSI.getCondition(),
+                                m_Not(m_Specific(SI.getCondition())))) {
+          NSI.setInverted();
+          SIGroup.push_back(NSI);
         } else
           break;
         ++BBIt;
@@ -783,6 +823,12 @@ void SelectOptimizeImpl::collectSelectGroups(BasicBlock &BB,
       if (!isSelectKindSupported(SI))
         continue;
 
+      LLVM_DEBUG({
+        dbgs() << "New Select group with\n";
+        for (auto SI : SIGroup)
+          dbgs() << "  " << *SI.getI() << "\n";
+      });
+
       SIGroups.push_back(SIGroup);
     }
   }