[llvm] [ValueTracking] Handle non-canonical operand order in `isImpliedCondICmps` (PR #85575)

[Nikita Popov via llvm-commits]

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@@ -8532,6 +8532,15 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
   CmpInst::Predicate LPred =
       LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate();
 
+  // We can have non-canonical operands here so canonicalize constant to L1/R1.
+  if (match(L0, m_ImmConstant())) {
+    std::swap(L0, L1);
+    LPred = ICmpInst::getSwappedPredicate(LPred);
+  }
+  if (match(R0, m_ImmConstant())) {
+    std::swap(R0, R1);
+    RPred = ICmpInst::getSwappedPredicate(RPred);
+  }
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nikic wrote:

Can we handle this by checking operand equality instead, as you did in the other patch? I'm thinking there is some cleanup to be done here: We have areMatchingOperands checking for swap, and then we also have it in the isUnsigned() code path below, and then this adds another case.

Or does that run afoul of the case where the constants are equal?

https://github.com/llvm/llvm-project/pull/85575