[llvm] [InstSimplify] Extend icmp-of-add simplification to sle/sgt/sge (PR #168900)

[Yingwei Zheng via llvm-commits]

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@@ -3261,20 +3261,22 @@ static Value *simplifyICmpWithBinOpOnLHS(CmpPredicate Pred, BinaryOperator *LBO,
 
 // If only one of the icmp's operands has NSW flags, try to prove that:
 //
-//   icmp slt (x + C1), (x +nsw C2)
+//   icmp slt/sgt/sle/sge (x + C1), (x +nsw C2)
 //
 // is equivalent to:
 //
-//   icmp slt C1, C2
+//   icmp slt/sgt/sle/sge C1, C2
 //
 // which is true if x + C2 has the NSW flags set and:
-// *) C1 < C2 && C1 >= 0, or
-// *) C2 < C1 && C1 <= 0.
+// *) C1 <= C2 && C1 >= 0, or
+// *) C2 <= C1 && C1 <= 0.
 //
 static bool trySimplifyICmpWithAdds(CmpPredicate Pred, Value *LHS, Value *RHS,
                                     const InstrInfoQuery &IIQ) {
-  // TODO: only support icmp slt for now.
-  if (Pred != CmpInst::ICMP_SLT || !IIQ.UseInstrInfo)
+  // TODO: support other predicates.
+  if ((Pred != CmpInst::ICMP_SLT && Pred != CmpInst::ICMP_SGT &&
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dtcxzyw wrote:

Use `!ICmpInst::isSigned`

https://github.com/llvm/llvm-project/pull/168900