1 files changed, 45 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
index c20e9d0..4e3aaf5d 100644
--- a/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CombinerHelper.cpp
@@ -6864,6 +6864,23 @@ bool CombinerHelper::tryFoldSelectOfConstants(GSelect *Select,
     };
     return true;
   }
+
+  // select Cond, 0, Pow2 --> (zext (!Cond)) << log2(Pow2)
+  if (FalseValue.isPowerOf2() && TrueValue.isZero()) {
+    MatchInfo = [=](MachineIRBuilder &B) {
+      B.setInstrAndDebugLoc(*Select);
+      Register Not = MRI.createGenericVirtualRegister(CondTy);
+      B.buildNot(Not, Cond);
+      Register Inner = MRI.createGenericVirtualRegister(TrueTy);
+      B.buildZExtOrTrunc(Inner, Not);
+      // The shift amount must be scalar.
+      LLT ShiftTy = TrueTy.isVector() ? TrueTy.getElementType() : TrueTy;
+      auto ShAmtC = B.buildConstant(ShiftTy, FalseValue.exactLogBase2());
+      B.buildShl(Dest, Inner, ShAmtC, Flags);
+    };
+    return true;
+  }
+
   // select Cond, -1, C --> or (sext Cond), C
   if (TrueValue.isAllOnes()) {
     MatchInfo = [=](MachineIRBuilder &B) {
@@ -7045,6 +7062,34 @@ bool CombinerHelper::matchSelectIMinMax(const MachineOperand &MO,
   }
 }
 
+// (neg (min/max x, (neg x))) --> (max/min x, (neg x))
+bool CombinerHelper::matchSimplifyNegMinMax(MachineInstr &MI,
+                                            BuildFnTy &MatchInfo) const {
+  assert(MI.getOpcode() == TargetOpcode::G_SUB);
+  Register DestReg = MI.getOperand(0).getReg();
+  LLT DestTy = MRI.getType(DestReg);
+
+  Register X;
+  Register Sub0;
+  auto NegPattern = m_all_of(m_Neg(m_DeferredReg(X)), m_Reg(Sub0));
+  if (mi_match(DestReg, MRI,
+               m_Neg(m_OneUse(m_any_of(m_GSMin(m_Reg(X), NegPattern),
+                                       m_GSMax(m_Reg(X), NegPattern),
+                                       m_GUMin(m_Reg(X), NegPattern),
+                                       m_GUMax(m_Reg(X), NegPattern)))))) {
+    MachineInstr *MinMaxMI = MRI.getVRegDef(MI.getOperand(2).getReg());
+    unsigned NewOpc = getInverseGMinMaxOpcode(MinMaxMI->getOpcode());
+    if (isLegal({NewOpc, {DestTy}})) {
+      MatchInfo = [=](MachineIRBuilder &B) {
+        B.buildInstr(NewOpc, {DestReg}, {X, Sub0});
+      };
+      return true;
+    }
+  }
+
+  return false;
+}
+
 bool CombinerHelper::matchSelect(MachineInstr &MI, BuildFnTy &MatchInfo) const {
   GSelect *Select = cast<GSelect>(&MI);