[llvm] [InstCombine] Optimize unneeded float to int cast when icmp (PR #155501)

[Yingwei Zheng via llvm-commits]

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@@ -7611,6 +7613,208 @@ Instruction *InstCombinerImpl::foldICmpCommutative(CmpPredicate Pred,
   return nullptr;
 }
 
+enum class SignType {
+  Positive,
+  NonPositive,
+  Negative,
+  NonNegative,
+};
+
+/// Check signess of a constant integer or vector of integers
+///
+/// \param C constant to check for signedness
+/// \param SignType the sign type to check against
+///
+/// \return whether constant is signess corresponds with the requesed requested
+/// sign
+static bool checkConstantSignType(const Constant *C, SignType Sign) {
+  auto Check = [Sign](const ConstantInt *CI) {
+    switch (Sign) {
+    case SignType::Positive:
+      return !CI->isNegative() && !CI->isZero();
+    case SignType::NonPositive:
+      return CI->isNegative() || CI->isZero();
+    case SignType::Negative:
+      return CI->isNegative();
+    case SignType::NonNegative:
+      return !CI->isNegative();
+    default:
+      llvm_unreachable("Unknown sign type");
+    }
+  };
+
+  if (auto *CI = dyn_cast<ConstantInt>(C))
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dtcxzyw wrote:

Use `m_CheckedInt` matcher.

https://github.com/llvm/llvm-project/pull/155501