[IR] Add support for samesign in Operator::hasPoisonGeneratingFlags

Author: dtcxzyw

llvm/lib/IR/Operator.cpp

@@ -50,6 +50,8 @@ bool Operator::hasPoisonGeneratingFlags() const {
     if (auto *NNI = dyn_cast<PossiblyNonNegInst>(this))
       return NNI->hasNonNeg();
     return false;
+  case Instruction::ICmp:
+    return cast<ICmpInst>(this)->hasSameSign();
   default:
     if (const auto *FP = dyn_cast<FPMathOperator>(this))
       return FP->hasNoNaNs() || FP->hasNoInfs();

llvm/test/Transforms/InstCombine/icmp.ll

@@ -5368,7 +5368,7 @@ define i1 @icmp_and_inv_pow2_or_zero_ne_0(i32 %A, i32 %B) {
 
 define i1 @icmp_samesign_logical_and(i32 %In) {
 ; CHECK-LABEL: @icmp_samesign_logical_and(
-; CHECK-NEXT:    [[C2:%.*]] = icmp samesign eq i32 [[IN:%.*]], 1
+; CHECK-NEXT:    [[C2:%.*]] = icmp eq i32 [[IN:%.*]], 1
 ; CHECK-NEXT:    ret i1 [[C2]]
 ;
   %c1 = icmp samesign sgt i32 %In, -1