1 files changed, 21 insertions, 11 deletions

diff --git a/contrib/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp b/contrib/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp
index 5beac5547d65..78a833476334 100644
--- a/contrib/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/contrib/llvm-project/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -1189,14 +1189,26 @@ static Value *simplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
   if (Value *V = simplifyDivRem(Opcode, Op0, Op1, Q, MaxRecurse))
     return V;
 
-  // If this is an exact divide by a constant, then the dividend (Op0) must have
-  // at least as many trailing zeros as the divisor to divide evenly. If it has
-  // less trailing zeros, then the result must be poison.
   const APInt *DivC;
-  if (IsExact && match(Op1, m_APInt(DivC)) && DivC->countr_zero()) {
-    KnownBits KnownOp0 = computeKnownBits(Op0, /* Depth */ 0, Q);
-    if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero())
-      return PoisonValue::get(Op0->getType());
+  if (IsExact && match(Op1, m_APInt(DivC))) {
+    // If this is an exact divide by a constant, then the dividend (Op0) must
+    // have at least as many trailing zeros as the divisor to divide evenly. If
+    // it has less trailing zeros, then the result must be poison.
+    if (DivC->countr_zero()) {
+      KnownBits KnownOp0 = computeKnownBits(Op0, /* Depth */ 0, Q);
+      if (KnownOp0.countMaxTrailingZeros() < DivC->countr_zero())
+        return PoisonValue::get(Op0->getType());
+    }
+
+    // udiv exact (mul nsw X, C), C --> X
+    // sdiv exact (mul nuw X, C), C --> X
+    // where C is not a power of 2.
+    Value *X;
+    if (!DivC->isPowerOf2() &&
+        (Opcode == Instruction::UDiv
+             ? match(Op0, m_NSWMul(m_Value(X), m_Specific(Op1)))
+             : match(Op0, m_NUWMul(m_Value(X), m_Specific(Op1)))))
+      return X;
   }
 
   return nullptr;
@@ -4857,14 +4869,12 @@ static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
   // select ?, poison, X -> X
   // select ?, undef,  X -> X
   if (isa<PoisonValue>(TrueVal) ||
-      (Q.isUndefValue(TrueVal) &&
-       isGuaranteedNotToBePoison(FalseVal, Q.AC, Q.CxtI, Q.DT)))
+      (Q.isUndefValue(TrueVal) && impliesPoison(FalseVal, Cond)))
     return FalseVal;
   // select ?, X, poison -> X
   // select ?, X, undef  -> X
   if (isa<PoisonValue>(FalseVal) ||
-      (Q.isUndefValue(FalseVal) &&
-       isGuaranteedNotToBePoison(TrueVal, Q.AC, Q.CxtI, Q.DT)))
+      (Q.isUndefValue(FalseVal) && impliesPoison(TrueVal, Cond)))
     return TrueVal;
 
   // Deal with partial undef vector constants: select ?, VecC, VecC' --> VecC''