Elide redundant test instruction for signed comparison predicates

src/coreclr/jit/emitxarch.cpp

@@ -757,6 +757,21 @@ bool emitter::DoesWriteSignFlag(instruction ins)
     return (flags & Writes_SF) != 0;
 }
 
+//------------------------------------------------------------------------
+// DoesResetOverflowFlag: check if the instruction resets the OF flag to 0.
+//
+// Arguments:
+//    ins - instruction to test
+//
+// Return Value:
+//    true if instruction resets the OF flag, false otherwise.
+//
+bool emitter::DoesResetOverflowFlag(instruction ins)
+{
+    insFlags flags = CodeGenInterface::instInfo[ins];
+    return (flags & Resets_OF) == Resets_OF;
+}
+
 //------------------------------------------------------------------------
 // DoesResetOverflowAndCarryFlags: check if the instruction resets the
 //     OF and CF flag to 0.
@@ -1472,6 +1487,23 @@ bool emitter::AreFlagsSetToZeroCmp(regNumber reg, emitAttr opSize, GenCondition
         }
     }
 
+    if ((cond.GetCode() == GenCondition::SLT) || (cond.GetCode() == GenCondition::SGE))
+    {
+        if (DoesResetOverflowFlag(lastIns) && DoesWriteSignFlag(lastIns) && IsFlagsAlwaysModified(id))
+        {
+            return id->idOpSize() == opSize;
+        }
+    }
+
+    if ((cond.GetCode() == GenCondition::SGT) || (cond.GetCode() == GenCondition::SLE))
+    {
+        if (DoesResetOverflowFlag(lastIns) && DoesWriteZeroFlag(lastIns) && DoesWriteSignFlag(lastIns) &&
+            IsFlagsAlwaysModified(id))
+        {
+            return id->idOpSize() == opSize;
+        }
+    }
+
     return false;
 }
 

src/coreclr/jit/emitxarch.h

@@ -770,6 +770,7 @@ static bool HasRegularWideImmediateForm(instruction ins);
 static bool DoesWriteZeroFlag(instruction ins);
 static bool DoesWriteParityFlag(instruction ins);
 static bool DoesWriteSignFlag(instruction ins);
+static bool DoesResetOverflowFlag(instruction ins);
 static bool DoesResetOverflowAndCarryFlags(instruction ins);
 bool        IsFlagsAlwaysModified(instrDesc* id);
 static bool IsRexW0Instruction(instruction ins);