[llvm] [ConstraintElim] Unify no-wrap queries. (PR #223537)

[Florian Hahn via llvm-commits]

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@@ -660,79 +738,58 @@ static Decomposition decompose(Value *V, const ConstraintInfo &Info,
     V = Op0;
   } else if (match(V, m_SExt(m_Value(Op0)))) {
     // Looking through the sext is only valid if the operand is non-negative.
-    if (!preconditionHolds(Info, CmpInst::ICMP_SGE, Op0, 0))
+    if (!Info.isKnownNonNegative(Op0))
       return V;
     V = Op0;
   } else if (auto *Trunc = dyn_cast<TruncInst>(V)) {
     if (Trunc->getSrcTy()->getScalarSizeInBits() <= 64 &&
-        (Trunc->hasNoUnsignedWrap() || Trunc->hasNoSignedWrap())) {
-      Value *Src = Trunc->getOperand(0);
-      // A trunc nsw only truncates without unsigned wrap if its operand is
-      // non-negative.
-      if (!Trunc->hasNoUnsignedWrap() &&
-          !preconditionHolds(Info, CmpInst::ICMP_SGE, Src, 0))
-        return V;
-      V = Src;
-    }
+        isKnownNoWrap(Trunc, Info, /*Signed=*/false))
+      V = Trunc->getOperand(0);
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fhahn wrote:

Yep, some of the code can be shared, although those changes should be NFC and I'd prefer to keep this as separate cleanup change, so it is easier to verify NFC-ness

https://github.com/llvm/llvm-project/pull/223537