1 files changed, 22 insertions, 15 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 54539d2..06162c6 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2570,26 +2570,33 @@ static bool isKnownNonZeroFromOperator(const Operator *I,
     return isNonZeroShift(I, DemandedElts, Depth, Q, Known);
   }
   case Instruction::UDiv:
-  case Instruction::SDiv:
+  case Instruction::SDiv: {
     // X / Y
     // div exact can only produce a zero if the dividend is zero.
     if (cast<PossiblyExactOperator>(I)->isExact())
       return isKnownNonZero(I->getOperand(0), DemandedElts, Depth, Q);
-    if (I->getOpcode() == Instruction::UDiv) {
-      std::optional<bool> XUgeY;
-      KnownBits XKnown =
-          computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q);
-      if (!XKnown.isUnknown()) {
-        KnownBits YKnown =
-            computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q);
-        // If X u>= Y then div is non zero (0/0 is UB).
-        XUgeY = KnownBits::uge(XKnown, YKnown);
-      }
-      // If X is total unknown or X u< Y we won't be able to prove non-zero
-      // with compute known bits so just return early.
-      return XUgeY && *XUgeY;
+
+    std::optional<bool> XUgeY;
+    KnownBits XKnown =
+        computeKnownBits(I->getOperand(0), DemandedElts, Depth, Q);
+    // If X is fully unknown we won't be able to figure anything out so don't
+    // both computing knownbits for Y.
+    if (XKnown.isUnknown())
+      return false;
+
+    KnownBits YKnown =
+        computeKnownBits(I->getOperand(1), DemandedElts, Depth, Q);
+    if (I->getOpcode() == Instruction::SDiv) {
+      // For signed division need to compare abs value of the operands.
+      XKnown = XKnown.abs(/*IntMinIsPoison*/ false);
+      YKnown = YKnown.abs(/*IntMinIsPoison*/ false);
     }
-    break;
+    // If X u>= Y then div is non zero (0/0 is UB).
+    XUgeY = KnownBits::uge(XKnown, YKnown);
+    // If X is total unknown or X u< Y we won't be able to prove non-zero
+    // with compute known bits so just return early.
+    return XUgeY && *XUgeY;
+  }
   case Instruction::Add: {
     // X + Y.